S2 EP7: A Guide to Nebulae

Hello and welcome back to the part 2 of season 2 of this astronomy podcast. I’m your host Maanvinder and I will be taking you on another journey through cosmos and this time we will wander through the stellar nurseries where stars are born and that magical place is called nebulae. Now that you have a basic understanding of what are they but what they really are? In this episode, I will be talking about it, their types and will try to tell you about some beautiful nebulae that are helping astronomers understand the life cycle of a star from its birth to death. In other words Nebulae are a place where a star rises from the dead. Let’s get started

Nebulae are vast cloud of dust, hydrogen, helium and other ionized gases. The singular for it is Nebula. You will certainly be surprised finding out how they are formed because it is very interesting and you will definitely find it to your like. They can be formed by two ways either it is from supernova explosions or in a molecular cloud. So what happens in the earlier case is that when a star dies in a supernova explosion, it blasts out its outer layers, thus ejecting all the material that includes gases, dust and elements. In the process, the material ejected forms a shell like structure, moving outwards from the site of explosion and is called a Supernova Remnant. What triggers the star formation or I say makes them a nebula is the shock wave from the explosion which compress the nearby gas and dust, forming new star making regions within the remnant. Now let’s talk about the later, which is as part of star formation in molecular clouds. A molecular cloud is also a kind of a nebula but it mainly consists of molecular hydrogen, along with carbon monoxide and ammonia. They are denser and colder regions where star formation is actively happening comparing with nebula such as a supernova remnant.

New I want to shed the light for you on types of nebulae in the universe.

• Planetary Nebula- When a star like our sun dies, it doesn’t explode into a black hole or a neutron star. Instead, it shed its outer layers, which forms a beautiful cloud of glowing gas and dust due to the heat from the star’s core which ends up becoming a white jewel at the centre of the nebula. The best example of such nebula is the Ring Nebula. Located in the constellation Lyra about 2000 light years from the Earth, it also known as Messier 57. It was created when a Sun like star died during its red giant phase, by shedding its outer layers, leaving only a white bejeweled core at the centre and forming a planetary nebula surrounding it. Remember, i talked about the red giant, white dwarf and black dwarf phase of a main sequence star by taking Sun as an example. You might wanna check those three episodes out if you don’t get it.  At the centre of this nebula is a white dwarf and is 200 times more luminous than the Sun.
• Dark nebula- A dark nebula or an absorption nebula is a dense cloud of interstellar dust and gas that completely blocks out the visible light from objects behind it. I can name few Nebulae that fall under this category but I will like to tell you about one of my favorite. When I saw its picture, I was amazed and shocked that despite being a dark nebula, it is so beautiful. Coalsack nebula or Caldwell 99 is a dark nebula located in the constellation Crux, about 600 light years from the Earth. It is so dark that it blocks out light from any object behind it and is about 100 light years across. On a clear night, it can be seen as a dark patch obscuring a part of the Milky Way in the sky.
• Emission Nebula- It is formed due to the high energy UV radiation from the newly born stars which ionize the surrounding gas. This type of emission nebula is known as HII region. The other type of emission nebula is the planetary nebula in which a dying star has blown off its outer layers and the hot core ionizes the surrounding gas. So you can include the planetary nebula I discussed earlier as one of the type of emission nebula. One of the best examples of HII region are the Heart Nebula and Soul Nebula, together which are known as Heart and Soul nebula. Both of them are located about 6000 light years from the Earth in the Perseus arm of our galaxy, in constellation Cassiopeia. Another example of emission nebula is the famous Bubble Nebula or NGC 7635. It is located about 8000 light years in the constellation Cassiopeia. It is called Bubble nebula because of a bubble created by the stellar winds from a young star known as SAO 20575. The star is located at its centre and is about 45 times massive than our Sun. The bubble nebula is a massive cloud of gas and dust that is about 10 light years across and is also an HII region because the stellar winds from the central star have ionized the gas in the nebula. The star is about 4 million years old and comparing it with the Sun which is 4.6 billion years old, its lifetime is very short because the more massive a star the faster it runs out of its fuel. That’s why Red Dwarf stars have an age of trillions of years because they are small compared to other stars and burns their fuel slowly. This star is now burning helium after losing all its Hydrogen and in about 10 to 20 million, the star will end its life in a supernova explosion. Emission nebula often appears reddish or pinkish due to the light emitted by the ionized Hydrogen gas.
• Reflection Nebula- A nebula which glows because of the light from an embedded star which illuminates its dust. Unlike other types of nebula, the Reflection nebula does not emit light of its own. The best example to explain this kind of nebula is NGC 1999. It is located in the constellation Orion at around 1500 light years from the Earth. What illuminates this nebula is a variable star called V380. A variable star is a star whose brightness changes with time and are used my astronomers to measure distances across the Universe. The star is located at the centre of this nebula and the light from it illuminates this nebula. Another interesting thing about this nebula is that there is a one more nebula present inside the same nebula. Near the centre of NGC 1999, there is a dark cloud which resembles letter ‘T’ from the English alphabets. This type of dark nebula is called Bok Globule and that means star formation is taking place in that dark cloud near the centre of NGC 1999. They often appear blue because they reflect more blue light than any other light. Fascinating is it not? Universe does surprise you in a way you never know whether it’s possible or not.
• Supernova Remnant- A Supernova remnant is a type of nebula which is result of a supernova explosion in which a star dies. They distribute heavy elements throughout the universe, they borrowed to form them and now the ejected material will contribute to the formation of new stars. One of my favorite supernova remnant is Cassiopeia A, located about 11,000 light years in the constellation Cassiopeia. It is a remnant of a dead star, which astronomers believe was about five times the mass of Sun before its brutal death. One fun fact, in 2013, Phosphorus was detected in it, confirming that this element is born inside a supernova.

This is all from me for this episode but hey I’ll be back with a new guide to guide you through this vast cosmos. thank you!!

S2 EP6: Journey to Exoplanets Beyond Our Solar Shore

Welcome back friends for another episode of this astronomy podcast, I’m your host Maanvinder and today we’re going on a new journey to the world of exoplanets that are way more complex than the planets in our solar system. 

Our universe is huge and expanding, with billions of galaxies which have billions of stars and so billions of planets in the universe. The only one that we know where life exist is our own home planet Earth. Earlier as you might know peoples used to believe that planets only exist in our solar system until Copernicus changed when he came up with his theory that Earth revolves around the Sun. Updating this same theory in sixteenth century Italian Philosopher Giordano Bruno put forward his idea stating fixed stars are also like the Sun which have their own planets. In Astronomy, there is a different term for such planets which do not revolve around the Sun and are called exoplanets, meaning planets outside our solar system. Later in the 20th century, astronomers knew that exoplanets exist but they were yet to be discovered. The first confirmed exoplanet was discovered in 1992. By 1 July 2024, 6660 exoplanets were discovered through various methods that I will later talk about in this episode. But first let’s talk about their formation.

Formation & Types

Exoplanets are no different from planets in our solar system when it comes to their formation. However, they might change from one type to another because of some extreme conditions. Exoplanets just like planets are born in a nebula where star formation takes place. They are formed from the leftovers of a star which has died and when a new star is born. The remaining dust and gas that could not accumulate into a star because they lack mass enough to turn into a star, end up becoming a planet or in this case an exoplanet. According to NASA, exoplanets can be categorized into gas giant, Neptunian, Super Earth and Terrestrial. However, they can also be sub categorized based on several factors and can also be categorized into other types but those four are the main. They come in different sizes and shapes like WASP-12b (an rugby ball shaped exoplanet, which is being devoured by its host star), exoplanets that orbit two stars like Kepler-16b (the stars it orbits are smaller than our Sun; one is 60%the mass of Sun and other only 20%). They can boil you easily if melting a metal and glass is easy for them and the best example is 55 Cancri-e. There are planets which are wandering alone in the vastness of space. Now I will tell you about those main 4 categories, astronomers divides exoplanets in to have a better understanding of their formation.

1. Gas Giant- These are planets that are the size of our local neighbors Jupiter and Saturn. In fact, they are also gas giants and it is true that gas giants are also found outside our solar system. They are gaseous. Now if I talk about the sub category, then Hot Jupiter’s are the best example of it. They are basically the gas giants that are tidally locked with their stars, they are gaseous and are scorching heat. They formed in the cold regions but later migrated into the system and are now tidally locked; meaning one side is burning hell and other chilling cold. I can also categorize it into another type, say Ultra Hot Jupiter. They are even hotter than Hot Jupiter’s are and are mostly being devoured by their host stars. For better understanding of our universe, astronomers divide them into different categories to understand more about them. One example of Gas Giant will be Kepler-16b. If you were paying attention then you would know I talked about it earlier. It orbits two stars and was discovered in 2011 using NASA’s Kepler Spacecraft by transit method. It is cold, gaseous and composed of rocks, located about 200 light years from the Earth.
2. Super Earth- They are massive than Earth but smaller than Neptune. They can be terrestrial or full of water. They become huge because they quickly attain the thick atmosphere of hydrogen and helium. The two best examples of Super Earth that comes in my mind are 55 Cancri-e and Kepler-22b. The earlier is tidally locked with its host star and it is so hot that it rocks gets vaporized only to rain back as lava on the night side while later is a water planet whose more than 95% surface is believed to be Ocean as it is located in its star’s habitable zone where liquid water can exist.
3. Neptunian Planet- They are similar in size to Neptune and Uranus and have thick hydrogen and helium atmosphere with a rocky core. They can be sub categorized into Mini-Neptunes, which are smaller than Neptune but larger than Earth. They can become super-earth if they loses their atmosphere. It might not seem case for other planets but it surely fits in the case of Neptunes. In a rare discovery in 2022, astronomers at W.M Keck Observatory and those using NASA’s Hubble Space Telescope discovered two different mini-Neptunes that were losing their atmospheres turning into super earth. I also talked about this discovery last season. As I mentioned earlier about super earth and mini-Neptune, there is one thing in common that they both are bigger than Earth but smaller than Neptune. That brings us to the conclusion that Super Earth can also form when a mini-Neptune loses its atmosphere due to radiation from their host star. In fact the smaller planets in many star systems are believed to be Mini Neptunes who lost their atmospheres due to their host star’s intense radiation.
4. Terrestrial- rocky planets who failed to have thick atmospheres of hydrogen and helium or if they had a thick atmosphere but lost it because they lost their magnetic field just like Mars in our solar system and do not confuse it with the case of mini-Neptune losing atmosphere to become super earth because they are smaller than the Super Earth.

Other types of these exoplanets include:

1. Puffy Planets- gas giants with a puffy appearance just like a cotton candy. I will tell you about these in more details in one of upcoming episode.
2. Rogue Planets- planets that do not orbit a star and drift through the space.

Detection Methods

There are many methods to detect the presence of an exoplanet. One of the best methods is called Transit Method in which astronomers uses the dip in the curve of light coming from a star to detect an exoplanet. Say there is a planet far from Earth orbiting its host star and we don’t know that there is a planet orbiting around that star. In order to find out, we will point our probe in this case let’s take NASA’s TESS mission, towards a star and we wait for the dip in the light that comes from the star. When an exoplanet passes in front of a star, it causes the light coming from the star to dip, which is then used to determine the size of the planet. This method is called transit method and is one of the most effectively used methods to discover an exoplanet by the science community.

Another method is Pulsar Timing. Actually this was the method which made the first detection of an exoplanet surrounding a Pulsar. In this method if a planet is orbiting a pulsar, then it will cause anomalies in the timing of observed radio pulses that is the radio waves that it emits regularly as it rotates. The next popular method after transit method is Radial Velocity or Doppler method. In this method, astronomers use the light coming from the star. Still didn’t understand it. Okay so think about the space time curvature and if you did the experiment or at least saw a video of it that how when planets move around a star, they causes the star to wobble. When a planet orbits a star, their gravity causes their star to wobble and this affects the light coming from the star. If a star is moving towards then the light will be blue and if moving away, then red. That’s the basic science of Doppler shift here. By noticing the color change in the star’s light spectrum, astronomers can detect the wobble thus the presence of an exoplanet.

There’s one other method that I want to talk about and it is called Gravitational Microlensing. You may have heard about it when James Webb Space Telescope released its first images which surprised everyone and in one of the image, gravitational lensing can be seen very clearly. The image is called Webb’s First Deep Field and shows many objects like stars, galaxy clusters, and distorted background galaxies behind the galaxy star. According to Einstein’s theory of general relativity, massive objects can bend light and it is called Gravitational Lensing. When a planet passes in front of a distant star, the planet’s gravity bends and magnifies the light from the background star. This causes the background star to temporarily brighten, which can be detected by telescopes. By studying the pattern and amount of brightening, astronomers can determine the presence, mass and even distance of the exoplanet. There are so many methods to discover exoplanets but these were one of the mostly used and successful ones.

NEWS: James Webb Detected Hydrogen Sulfide on an Exoplanet

What never fails to amaze me is the fact that there must be an exoplanet where life exists. In fact, 1 in 5 Sun like star have one Earth sized planet in their habitable zone. Okay now I will tell you about the recent news about an exoplanet called HD 189733b, located in the constellation Vulpecula about 64.5 light years from our solar system. Recently NASA’s James Webb Space Telescope has detected the presence of Hydrogen Sulfide, a gas which smells like an rotten egg. The gas is also an indicator of presence of life. However, in case of this planet it is not true. Wanna know why? Then close your eyes and imagine what I’m about to tell you. You are standing on a planet which is so close to its star that it is tidally locked. The dayside of the planet always faces the star and night side always faces out into the space. The dayside is hot enough to evaporate glass and when this happens, the high speed winds carries away that molten to night side where it condenses and rain down as glass. Would you be able to survive on a planet where instead of your normal rain like on Earth, rains glass that can pierce through your body. I would not dare to spend a minute on that planet. However, it will be totally impossible to stand on it as the planet is a gas giant and to be clearer it is a Hot Jupiter. Remember I told you earlier about this type of exoplanets. So in conclusion the discovery of Hydrogen Sulfide means the planet will smell an rotten egg. This gas makes most of the planet’s atmosphere and don’t get attracted towards its beautiful blue color because that comes from clouds of glass. This has however is also found on Jupiter but it is one of the first detection on an exoplanet which is crucial in understanding the atmosphere, and life of a planet. HD 189733 b was discovered in 2005 using a method called radial velocity that I talked about earlier in the episode. It has an orbital period of 2.2 days because of it being so close to its star.

S2 EP5: What if Our Sun became a White Dwarf Star?

Hello and welcome back to another episode of this astronomy podcast and I’m your host and it’s time to finally embark on another adventure through our cosmos. Last season, I told you guys about some scenarios regarding the future of Sun like what if our Sun became a black hole, red giant star and black dwarf. One scenario out of these three will never come true and that is the one about black hole because Sun does not have mass enough to become a black hole instead it will become a black dwarf, which is the last evolutionary stage for a main sequence star. Before that happens, Sun will become a red giant star by growing its outer layers, engulfing planets and moons, etc. It is after this stage that is a new stage called White Dwarf and in this episode we will be discussing about it.

What is white dwarf? It’s not that hard to understand if you can understand the common science behind it. Our Sun is a main-sequence star which means it burns hydrogen to helium in a process called fusion, which is how it produces energy and light. When it runs out of fuel, it begins to fuse helium and other heavy elements produced inside it and will take the charge to prevent the star from collapsing under its own gravity. In this stage, the Sun’s outer layers begin to expand outwards. It is balanced by the star’s own gravity and the outward pressure from ongoing thermonuclear process. Roughly 5 billion years from now the Sun will enter the Red Giant phase. There comes a time it will run out of it as well and shed its outer layers because there will be no more thermonuclear reaction to prevent it from collapsing under its own gravity. When it will shed its outer layers, it will form a planetary nebula such as Carina Nebula. It is just like a supernova however there is one difference. In the blast of outer layers, Sun will throw all the elements and stuff into the outer space making a nebula, leaving a small sparkling jewel. It will continue to shine due to thermal heat from the process going inside it. However, it does not mean the Sun’s mass will also reduce to that of the Earth. According to Dr. John from NASA’s Goodard Space Station, the Sun will lose its 50% mass affecting the entire solar system. The sun will become dense and it will have an intense gravitational pull due to the electron degeneracy pressure. In this process the electron gets squeezed together, the more the electron gets squeezed, the denser the star gets. This pressure prevents white dwarfs from collapsing however; it does set a limit on it.

Earlier it was believed that all main-sequence stars turns into white dwarf and does not undergo supernova. This was changed when an Indian-American astrophysicist Subrahmanyan Chandrasekhar discovered a limit called Chandrasekhar Limit. According to this limit, a white dwarf can also become a neutron star by undergoing a supernova called Type Ia Supernova if the mass of white dwarf is about 1.4 times that of the Sun. Another way to go supernova is if it gains mass and this is possible if it comes in a contact with a red giant star, which usually happens in a binary star system where one is in red giant phase and the other is in the white dwarf. As red giant has lower control on its outer layers due to it being only supported by the thermonuclear reactions pressure, the white dwarf will begin to collect or in other words steal the material from its companion red giant until it reaches a point called Chandrasekhar Limit where it will undergo a supernova explosion, resulting in a neutron star. This possibly leaves a white dwarf and a neutron star because the continues flow of material from red giant to white dwarf causes the process of the other red giant turning into white dwarf gets increases and it loses its outer layers before it has a chance to burst the layers on its own naturally.So is it possible in case of Sun? if you were paying attention you would know that our Sun will never undergo this process of becoming a neutron star let alone a black hole. First if its mass was 0.4 times more than it has, it would have certainly undergone a supernova. Another reason is that there is no close star for our sun to collect material to reach that limit. So yeah, its safe to say that deadly fate is not in our sun’s evolution stage.

With this thing I would like to draw your attention towards one more thing, when our Sun will be in its red giant phase, it will engulf everything till Jupiter according to latest models. That means our planet will be gone, the mars will be gone, the asteroid belt will be gone. The question that arises here is will life exist then? Then answer might be yes because when the Sun will be near Jupiter, its habitable zone will gets shifted beyond Jupiter’s orbit, somewhere around Pluto, Neptune and Kuiper Belt, possibly giving life a second chance to thrive. However, I’m not sure of the fate after that because when Sun will blow its outer layers, which mean it will blow up everything in its wake. Astronomers used to think that there will be no planets orbiting it until they discovered one white dwarf with planets. Now we know planets can still orbit an white dwarf. For example, WD 1586 b is a Jupiter sized exoplanet orbits the white dwarf every 34 hours. It was discovered by NASA’s Spitzer Space Telescope while analyzing data from NASA’s TESS mission in which transit method is used to discover new planets. I will explain about this in the next episode. Another such example is of SDSS J1228 which is just the metal core of a dead planet, revolving around a white dwarf. White dwarfs also have their own habitable zone. That means when our Sun becomes a white dwarf, the habitable zone will once again gets shifted back from Pluto to a new place, where if a planet survived the outburst of sun’s layers, the liquid water on it might exist if it is revolving inside this zone. That is for the future to decide. White dwarfs take billions of years to cool down and when they do, the last stage will be turning into a black dwarf if it is a white dwarf with mass no more than 1.4 or more than that. White dwarf has thin atmosphere of hydrogen and beneath it lies a thick surface of helium around 30 miles thick whose interior is made of super heated carbon and oxygen because it is these elements whose electrons gets squeezed to make a white dwarf denser. The surface temperature of a white dwarf can be as hot as half million degrees but over the course of billions of year, it will cool down to a point when it will be remain left as a cold dark ball lurking in the space and planets or any celestial body will still be orbiting around it except one thing that will change. It will be pure darkness and darkness for anyone to stand there, thus bringing an entire star system to its silent and dark death.

That is from me now until we meet again for the next episode. Stay tuned!!

S2 EP4: Neptune's Moon Triton

Welcome back everyone, to another exciting episode of this astronomy podcast, where we journey through the wonders of the universe. I'm your host, Maanvinder, and today, we're diving deep into icy depths of a fascinating celestial body or i say Neptune’s moon Triton.

Triton is the seventh largest natural satellite in the solar system and also the biggest moon of Neptune out of its 16 moons. Another fascinating thing about this moon is that it was discovered just 17 days after Neptune by a British astronomer William Lassell on October 10, 1846. Apart from galaxies and nebulas, natural satellites of planets in our solar system never fail to amaze me. I remember when I would write down the names of all moons in my science note book and dedicate a separate page for the particular moon just to add interesting facts about them and some of my favorite one include two moons of Mars, Saturn’s Moon Titan, Jupiter’s moon Io and many other small moons of Saturn. I’m sure you all are aware of that feeling where you just wanna know so much about this cosmos.

Do you know that Triton is believed to be an Kuiper belt object? If you don’t know then let me tell you why scientists thinks it’s one of those Kuiper belt objects. It is the only moon in the solar system that moves in an retrograde orbit, which means rotating opposite to the Planet’s rotation. According to current astronomical models, any moon that formed surrounding a planet will rotate in the same direction as that of the planet but in case of this moon, it’s the opposite case. That’s why scientists believe it is an Kuiper belt object that was captured by Neptune in its orbit. Another interesting thing related to its rotation is that it is tidally locked with Neptune due to its closer distance to the planet which means only one side of Triton always faces the planet and the other side remains hidden from point of view of someone who is standing on Neptune. Well you basically cannot stand on the planet but imagine that for your understanding. Okay let’s use the example of our moon. We never see the other side, the dark side of moon because it is tidally locked with the Earth.

Neptune is literally the death of this beautiful moon. You know why? Like I said earlier, Triton is tidally locked to its planet but the only difference between Triton and Earth’s moon is that Triton is way closer to its planet than our Moon is to the Earth. That is why, due to tidal interactions from Neptune, it is getting pulled into the Neptune’s orbit and once it crosses the Roche Limit of Neptune, Triton will begin to fall apart into pieces, colliding with the planet and making a new set of rings around the planet just like Saturn and this time it will be denser than the current ones. If you still don’t get it, remember the episode of previous season in which I talked about an exoplanet called WASP-12b which is being devoured by its host star as it is tidally locked and the tidal interactions from its host star continue to eat this planet. Okay so one thing I wanna make clear here is that this is not the fate of our Moon, even though it is also tidally locked. Our moon is drifting away from Earth. Scientific predictions suggests that in about 3.6 billion years, Triton will enter the Neptune’s Roche limit, thus beginning leading this moon towards its death. Another interesting thing I wanna tell you about this moon is it is one of the few moons with atmosphere in our solar system like Saturn’s moon Titan. It has a thin atmosphere composed primarily of nitrogen, smaller amounts of carbon monoxide and Methane. Carbon Monoxide was first detected back in 2010 through ground based telescopes and it was found that it is more abundant than Methane. NASA has proposed a future mission to study Triton and it is called Trident which will be launched in October 2025, arriving on the moon in 2038 to study it in more details. The last time a probe or mission to study was when Voyager 2 flew past it in August 1989 during its closest approach to Neptune, when it discovered that Nitrogen and Methane presence, confirming previous theories regarding their presence by astronomers. The atmosphere of Triton is sustained mainly due to the cryovolcanic activity on the surface of the moon, which means the eruption of gases, liquids and ice from the surface. Cryovolcanoes on the surface of Triton erupt nitrogen and other volatile liquids. This suggests the presence of a reservoir of liquid water and volatile compounds.

A day on Triton lasts for about 5.8 Earth days and due to it being tidally locked with the Neptune, there is no doubt in accepting the temperature difference between the two different sides of the moon. During its flyby Voyager 2 found the surface temperature to be -235 degree Celsius, however the temperature difference between two sides would be completely different if we take one side of the Triton that is always in dark. Even though Triton is one of the coldest objects in the solar system, it does have a heating system. Remember the tidal interactions I told you earlier about, it is because of these tidal interactions that the cryovolcanic activity is possible on this Moon, keeping liquid water beneath its frozen nitrogen surface. I asked planetary scientist & astrophysicist Sean Raymond about this to which he replied, “Tidal heating would be distributed evenly across Triton but solar heating would vary from one hemisphere to the next over Titan’s 5.9 days orbital period around Neptune. I Titan is very far away from the Sun so it’s not very warm anyways”. I recommend you guys to check out his blog planetplanet.net.

Triton is one of the few geologically active moons in our solar system thanks to its cryovolcanic activities due to the tidal interactions from Neptune. Also, the moon is larger than the dwarf planet Pluto at around 2710 km in diameter. It is also the largest retrograde moon in Solar System and comprises about 99.5% of total mass that orbit Neptune while the remaining moons and rings making only 0.5% of the total mass. I believe you have been surprised to know so many facts about the moon so far then let me tell you one more. Titan appears to be reddish in color. Why? Well it is because of the methane ice. That's all for today's journey through Triton. Join me next time as we embark on another cosmic adventure. Until then, keep gazing up at the stars!

S2 Episodes List Pt.2

Hello

This is your host Maanvinder, back with the dates for new episodes of Season 2 of Astrophysics: Deep In The Space With Maanvinder Pilania. Below are the dates for some of the S2 EP List Pt.2 including the dates of remaining 3 episodes from S2 EP List Pt.1

EPISODES PT.2

EP-4 Neptune's Moon Triton- July 12, 2024
EP-5 What If Our Sun Became a White Dwarf Star?- July 15, 2024
EP-6 Exoplanet: Formation & Their Types- July 18, 2024
EP-7 A Guide to Nebula- July 21, 2024
EP-8 A Guide to Galaxies- 
EP-9 Super Puff Planets- 
EP-10 Trip to Martian Moons-

S2 EP3: A Guide to the Local Group

Hello and this is Maanvinder and I’m back with another episode. Today I I will tell you about a fascinating group of galaxies, our galaxy is part of. But before I move forward, I want you to imagine no of galaxies in our universe. 1, 2 or 5 million or 1 billion or 200 billion. If your answer is more than 200 billion, then you are correct. There are between 200-300 billion galaxies in our observable universe. And these galaxies are not just scattered through the universe, in fact they are part of a large group of galaxies due to their mutual gravity, just like the star clusters I told you about in the previous episode but in this case its on a large scale, we are talking millions of light years and they are galaxies and not individual stars in a galaxy. Such kind of group of galaxy is “Local Group”. Local Group is dumb-ball shaped like group of galaxies. Our own Milky Way galaxy is part of this group. When I said dumb-ball, I meant it looks like that with Andromeda, our neighbor galaxy at one lobe and Milky Way at the other. The Local Group was first recognized by the American astronomer Edwin Hubble.

The Local Group has around 80 galaxies and most of them are either dwarf galaxies or satellite galaxies. The three largest members of the Local Group are: Andromeda or M31; the biggest, Milky Way; the second- biggest and Trapezium Galaxy; third biggest. The two biggest galaxies in the group are spiral galaxies and accounts for most of the mass in the group. Each of these two galaxies has their own system of satellite galaxies which revolves around them. Another interesting thing about these two galaxies is that they are on a collision course with each other and in about 5 billion years they will completely merge into each other forming a new galaxy and who knows maybe will be called as ‘milkomeda’. Local Group has roughly a diameter of 10 million light years and is part of a very large cluster of galaxy groups called Virgo Supercluster which is located 70 million light years from the centre of Local Group. There’s still debate over the centre of Local Group but it is believed to lie between Andromeda and Milky Way.

The current computer models has predicted the future of Local Group to be a large single elliptical galaxy. Tens of billions of years into the future all galaxies in the system will merge into each other. After Andromeda and Milky Way will merge into each other along with their satellite galaxies, then the third biggest member of this system, the Trapezium galaxy will merge into the newly formed “milkomeda”. And this merger will continue until all the galaxies merge into each other. As you know the universe is expanding so all the galaxies are moving away from ours except those who are part of the Local Group, so in the future there will be just one galaxy as all the other galaxies will pass the horizon and we will never be able to see them, what will be left is that large single elliptical galaxy. So its time to know about some galaxies other than the big three I told you about.

So at number one we have Magellanic Clouds. These are two satellite galaxies of the Milky Way. Large Magellanic and Small Magellanic Cloud are their names. What is more interesting about these two that there is a bridge called “Magellanic Bridge” between them which is a stream of hydrogen connecting these two galaxies where stars from SMC are being pulled towards LMC. SMC is located some 197,000 light years while LMC is located approximately 163,000  light-years from the Earth and is on the collision course with the Milky way. It will merge in about 2.5 billion years.

So this was from me for this episode. I hope you love it and let me know about it in the comments, polls or review section of the platform you are listening this podcast on.

S2 EP2: A Guide to Star Clusters

Hello and welcome back to my podcast. In this episode, I will tell you guys about the star clusters, their types and will also tell you about some of the very famous clusters like the Pleiades Star. So let’s get into it!

Before we start, you guys need to know the process behind the formation of a star. Stars are formed in large cloud of gas and dust called nebula. Gravity begins to form the clumps of the gas and dust, pulling more and more material into it, until it gets massive enough to collapse under their own gravity. Until then, they are proto-stars, and when these collapses they forms a star which is producing light. The leftover from the star formation becomes planets, asteroids, and comets just like what happened when our solar system was born. Stars are born in groups in a nebula and when all the proto stars collapses under their own gravity, they becomes stars and become what is called by astronomers as “star clusters”.

Star Clusters are groups of stars, hold together by their mutual gravity. There are hundreds of them in our galaxy. When talking about their types, then the answer is three: Open, Globular & Embedded Clusters.

Open Clusters are a group of a few to a few thousand stars born from the same cloud of gas and dust. If you are a astrophotographer, then they are a perfect target for you because you can see every star within the cluster using your telescope and sometimes with unaided eyes. The Pleiades is the best example of open star cluster. You can see them looking like a small Ursa Major constellation in the sky. To be honest, at first I literally had no idea what I was looking at until I realized that I was looking at the Pleiades all the time.  Pleiades are also known as the “Seven Sisters” cluster because there are 7 stars in it. In fact, there are more than 7, around 1000 stars but these seven are the brightest ones, which appear from the Earth.

Another interesting thing about these open star clusters is that they will not be forever like this. With the passage of time, they will get disperse in the space because of their gravitational disruptions in the space. Our Sun- the star which is source of light and energy was once a part of such cluster and was also separated from the other stars because of such gravitational disruptions. Open clusters are young group of stars and are found in the spiral arms of the spiral galaxies. There are more than 1000 of them in the Milky Way galaxy.

Moving into the Globular Clusters, they are more massive, older than the Open clusters. Globular clusters are a group of thousands to millions of stars, gravitationally bounded by each other. Unlike, the open star clusters they are not easy to photograph because the stars are so densely packed that you cannot distinguish them from each other, not even using the ground based telescopes. Powerful telescopes like Hubble and James Webb are good at doing this job though. According to NASA, they are home to some of the oldest stars in the Universe. As old stars tend to appear red, these globular clusters also appear to glow red. There are around 150 globular clusters in the Milky Way while the neighbor Andromeda has over 400 of these. They are much good at holding them together. They don’t decay with the time and so their strong gravitational attraction keeps all the stars together. The best example of a globular cluster is Messier 13 or M13- located in the constellation Hercules, about 25,000 light years from the Earth. Sometimes, this cluster is also known as the Great Globular Cluster or NGC 6205. The stars in the cluster are about 12 to 13 billion years old, almost as the same ages as our universe.

Now we’re on our last type of star cluster. It was pretty interesting so far. Now that you know about the two star clusters I told you before, the third type is pretty easier one to understand as the word embed in itself gives a lot of hint, as if the stars in these type of clusters are embedded in something. Embedded clusters are a group of stars which are born inside a nebula. It’s like early stage of star clusters in a nebula, while some stars have already born and some are still in the process of formation. The stars are that have already born are still in the nebula. Once the star formation in the nebula ends, the embedded clusters become open clusters. The best example of such an star cluster is Trapezium cluster, located in the Orion Nebula. It’s about 1600 light years from the Earth and is also known as the Orion Trapezium Cluster because of its Trapezium like arrangement of stars and due to its location. This cluster was discovered by the Italian astronomer Galileo Galilei. The cluster is very young about 300,000 years old. 

S2 EP1: The Mysterious Himiko Cloud

Hello, Ciao, Bonjour everyone. What’s up guys? Finally, I’m back with Season 2 of this podcast. I know y’all waited for over a year for it to start airing but its finally here. Today I will tell y’all about a mysterious object in our cosmos which is called Himiko Cloud. Confusing right? So let me break it down in simple terms.

Before we understand what this Himiko cloud is, you need to know what a lyman-alpha blob is. Because that is what this Himiko Cloud is. In astronomical terms, a Lyman-alpha blob or LAB is a huge concentration of hydrogen gas that emits the ultraviolet light of the Lyman-alpha emission line. They are the size of galaxies with some of them being more than 400,000 light years across. They are one of the largest objects in the universe. They are the early stage of the formation of galaxies. Now you might wonder what this lyman-alpha emission line is. So let’s make it easier to understand. Lyman-alpha is a spectral line of hydrogen spectrum which is emitted when the electronic transition takes place from 2^nd orbital to the ground state, releasing a photon in the process which is basically the UV light photon. I’m moving forward in this topic thinking y’all know what this electronic transition is. You need to have this basic knowledge in order to better understand what exactly LAB is. Also, as they are UV light photons so how do we see them? The answer is as they are so far away, billions of years, their light gets red-shifted to the optical part of the electromagnetic spectrum. Moving forward, now that you know about lyman-alpha emission line, let’s talk about our Himiko Cloud. 

Himiko Cloud was discovered back in 2009 and is indeed an object of interest for the astronomers because it existed at a time when our universe was only 800 million years old compared to today’s 13.1 billion years. It was found at a distance of 12.9 billion light-years and spans some 55,000 light-years. The speed of light is finite. It means the light from this object arrived in 2009 after travelling 12.9 billion light years. So we are seeing it how it looked like as it was 12.9 billion years ago.

The radial velocity of this object is 289575 km/s. Radial Velocity is the speed at which an object in space is travelling away or towards the space. If the speed is in negative then that means the object is coming towards the Sun but if the value is positive, it means the object is going away, which is true in the case of the Himiko Cloud. It is moving away from the Sun with the expansion of universe.

Located in the constellation Cetus, it was named by the scientists after one of the mysterious 3^rd century Japanese Shaman queen Himiko. Imagine how massive this object could be? According to astronomers, it is roughly equivalent to the mass of 40 billion Suns. This object remains a very big mystery to the astronomers till today.

Special EP: Science Behind The Interstellar Space

What do you think when you hears the word interstellar space? You probably think of the famous movie Interstellar. Now tell me what comes in your mind when you hear the word space? You probably thinks that the space is empty. Stars are so far away from each other and so most of the space is empty. But is it true?

Let me help break it down for you. Hi, I’m Maanvinder, your host of this podcast and I’m back with the season 2 of this podcast after two years and we are starting it with a special episode discussing about the interstellar space. The word interstellar is made up of two words- inter which means between and stellar means star. So Interstellar space is a place between the stars. Another question that arises here is where does it begin? So the correct answer based on the best available science is that, it starts where the star’s constant flow of material and the magnetic field stop affecting its surroundings. To put it in simple terms, for us the interstellar space begins where the sun’s constant flow of material and the magnetic field stop affecting its surroundings. And that place is called heliopause. And with the word material I meant electrons, solar wind, etc. It is the last boundary of a star up to where the star’s magnetic field, and any flowing material stop affecting the bodies outside place. The solar wind from our Sun creates a bubble around our solar system and this is called heliosphere. We know about this by detecting the temperature and concentration of solar particles. Inside this bubble, the solar particles are hot but less concentrated compared to the place outside this bubble where particles are cold and are largely concentrated. This is where you enter the interstellar space. Welcome you have finally made it into the interstellar space.

So as I earlier said, the interstellar space is not empty. The interstellar space is largely made up of Hydrogen which accounts for 70%, next is Helium (28%) and the remaining 2% is heavier gases, interstellar dust, and elements that are thrown out into the space in a supernova. If you don’t know heavier elements are born inside the stars and when the star dies, the blast out their outer shells, spewing all the materials out into the space. And it becomes a part of the interstellar space. If a particular region of the interstellar space has enough material for it to accumulate, then it can give birth to new stars in the stellar nurseries called the nebula.

The next question you might be wondering that has anyone or anything from our world entered the interstellar space? Well there is one. NASA’s Voyager-1 mission in 2012 made history by becoming the first man-made object to leave heliosphere and entered the interstellar space. This was confirmed from the detectors onboard the probe which detected the change in the concentration and temperature of particles that were hitting the probe. Voyager-1 was launched in the year 1977 to study the gas giants of our solar system. It actually did not visited them but flew past them, gathering data about the moons, their magnetic field, and most importantly rings. This is when it was discovered that Saturn is not the only planet with the ring system. Jupiter, Uranus and Neptune also have thin ring system around them. Now Voyager-1 is heading towards the Oort Cloud which is the last boundry of our solar system. It is a place where most of the long period comets origin from. It will reach the beginning in about 300 years and in 30,000 years it will exit our solar system completely. It will be lost in the vastness of deep space. 

So why is interstellar space important? The simple answer is without it we wouldn’t exist. Because it is a place where the stars are born in the thick region called molecular clouds- where there is so much material for it to accumulate and born as a star. Interstellar Space is also the place from where cosmic rays enter our solar system because when a star dies in a supernova explosion; it not only spews out elements but also the cosmic rays. During day and night there is a constant bombardment of these rays into the Earth’s atmosphere. When cosmic rays collides with the atoms into Earth’s atmosphere, all their energy is converted back to matter and shower down on Earth’s surface. So this was it from me for this week. Thank you for listening. See you next week!

S2 Episodes List Pt.1

Hello folks,

Maanvinder here back again to give y'all about the season 2 of my astronomy podcast= Astrophysics: Deep In The Space With Maanvinder Pilania, which is all set to air from January 13, 2024; that is exactly two years after the release of season 1. I will reveal all episodes in parts: Pt.1 & Pt.2. These two will make up a total of twelve episodes. If everything goes well, I will continue with the Pt.3 and more. But here are the episodes for the Pt.1 that will start to air from the January 13, 2024 to February 24, 2024, every Saturday at Spotify for Podcasters. By that time, you can listen to all 10 episodes of Season 1 at Spotify for Podcasters.

Thank You

EPISODES PT.1

Special EP- The Science Behind The Interstellar Space-January 13, 2024, Saturday

EP-1 The Mysterious Himiko Cloud-January 20, 2024, Saturday

EP-2 A Guide to Star Clusters-January 27, 2024, Saturday

EP-3 A Guide to the Local Group-February 3, 2024, Saturday

EP-4 Neptune's Moon Triton

EP-5 What If Our Sun Became a White Dwarf Star?

EP-6 Exoplanet: Formation & Their Types

Note- The last three episodes were later released with Pt.2 episodes.

Our Spotify Wrapped

Hello everyone,

I'm here to share about my Spotify Wrapped and thanks to everyone who listened our podcast so far. Today i logged in into spotify for podcasters account to start recording the new episodes which are all set to air from January. We found our Spotify Wrapped. Even with no new episode this year, we had so many new followers and the top percent of listeners were from the Brazil. Thank you to anyone who listened this podcast at any platforms. It means so much to me. The top listened episode was obviously the episode 1 which aired more than a year ago back in January 2022. Stay tuned  in because i have a lot in store to share with you guys!!

Top Episode

Top Listeners

Season 2 Announcement

Hello folks,

Maanvinder here to give y'all the latest update about my astronomy podcast- Astrophysics: Deep In The Space With Maanvinder Pilania. Its first season started airing back in January 13, 2022 and ended in June 12, 2022, with a total of 10 episodes. At first i decided to end this show because i barely had the time to record new episodes then share them. It takes a lot of time and energy to do that. Now after giving much thought, i have decided to come back with the Season-2 of the podcast. Season 2 will start airing from January 13, 2024; exactly two years after its first release. And i'm very excited to share what i have recorded so far. There will even be a Special Episode titled- "Science Behind The Interstellar Space". Actually the season 2 will start from this episode and then afterwards there will be EP-1 & so on. This special episode is for someone who is very dear to my heart and that person was the one who suggested it. So this special episode is for my special friend!

Thank You

Stream*

Spotify for Podcasters:- https://podcasters.spotify.com/pod/astromaanvinder/

Shukrayaan Mission [365 Days of Astronomy]

This is the fifth episode by Maanvinder Pilania for 365 Days Of Astronomy about India’s first mission to the Venus. Note that the episodes of this podcast are not always available to listen because the episodes are archived after some period of time but can be accessed at any time on their official website.

Description

After the successful missions like Mangalyaan to Mars and a series of Chandrayaan missions to Moon, ISRO will launch a mission to Venus in the year 2024. The mission has been named as Shukrayaan. Shukra is a Hindi word for planet Venus. It will be ISRO’s first mission to Venus.

The current status: Shukrayaan is still a planned mission with no fix date to launch soon.

Read & Listen

Shukrayaan Mission- January 25th, 2023, 365 Days of Astronomy.

check all episodes here.

A Journey to TOI 849b [365 Days of Astronomy]

This is the fourth episode by Maanvinder Pilania for 365 Days of Astronomy about TOI 849b Exoplanet which aired on September 28th, 2022. Note that the episodes of this podcast are not always available to listen because the episodes are archived after some period of time but can be accessed at any time on their official website.

Description

TOI 849b is an exoplanet located about 730 light years away from Earth. Due to its close proximity to its star the atmosphere of this exoplanet was blasted away by its host star, leaving behind a naked core. This is the first ever planetary core discovered by astronomers. 

Read & Listen

A Journey to TOI 849b- September 28th, 2022, 365 Days Of Astronomy

check all episodes here.

Ring System Around Astronomical Objects [365 Days of Astronomy]

This is the third episode by Maanvinder Pilania for 365 Days of Astronomy about the Ring System which aired on September 21st, 2022. Note that the episodes of this podcast are not always available to listen because the episodes are archived after some period of time but can be accessed at any time on their official website.

Description

Talking about the ring system, the only astronomical body that comes up in the mind of peoples is the planet Saturn which has a ring system which can be seen easily with the help of a telescope. But did you know that Saturn is not the only one that has these jewels. Even there is a planet which has a ring system bigger than that of the Saturn. All thanks to modern astronomy, which have been successful in finding such objects which have a ring system with the help of spacecrafts and telescopes.

Read & Listen

Ring System around astronomical objects- September 21st, 2022, 365 Days of Astronomy.

check all episodes here.

Fermi Bubbles of the Milky Way Galaxy [365 Days of Astronomy]

This is the second episode by Maanvinder Pilania for 365 days of Astronomy about the Fermi Bubbles which aired on September 13th, 2022. Note that the episodes of this podcast are not always available to listen because the episodes are archived after some period of time but can be accessed at any time on their official website.

Description

In 2010, gamma ray observations by NASA’s Fermi Space Telescope revealed an unknown mysterious structure of our home galaxy Milky Way. Astronomers discovered two giant bubbles that emerge below and above the center of our galaxy. They are known as Fermi Bubbles. Each bubble is about 25000 light years long, spanning a total length of about 50,000 light years. The structure spans more than half of the visible sky, from the constellation Virgo to the constellation Grus, and it may be millions of years old.

Read & Listen

Fermi Bubbles of the Milky Way Galaxy- September 13th, 2022, 365 Days of Astronomy.

check all episodes here

Olbers Paradox: Why the night sky is dark? [365 Days of Astronomy]

This is the first episode by Maanvinder Pilania for 365 days of Astronomy about Olbers Paradox which aired on July 12th, 2022. Note that the episodes of this podcast are not always available to listen because the episodes are archived after some period of time but can be accessed at any time on their official website.

Description

Looking up at the night sky, have you ever wondered why the night sky appears dark? Any explanation, I’ve got two explanations for you. Maybe you have never thought about that because what most of the peoples thinks about the darkness of night is that the Sun has set so there’s no brightness in the sky. But is it the right explanation behind the darkness of night sky or there might be another explanation? I used to think what most of the common peoples thinks about the darkness of night sky until I came to know the exact reason behind the darkness.

Read & Listen

Olbers Paradox: Why the night sky is dark?- July 12th, 2022, 365 Days of Astronomy.

check all episodes here.