Tag: SN1987A

Astronomy News for September 2023: The James Webb Space Telescope begins to show off what it can do.

Lifted into orbit back in (December of 2021) the James Webb Space Telescope (JWST) spent its first months in orbit calibrating its instruments while the world’s astronomers eagerly waited. Well JWST has been in operation for a little over a year now and NASA has taken the opportunity to release some of the more spectacular images sent back by the space telescope.

It was almost two years ago the the James Webb Space Telescope (JWST) was launched in orbit. Now astronomers are released some of the first results, the first discoveries made by this largest and most advanced space telescope. (Credit: Safran)

First a bit of a reminder, JWST operates as most large astronomical telescopes do by taking long exposure digital images of whatever astronomical object it is studying. Most of those ‘deep space’ objects are actually very dim and the only way to get good images is to open up the telescope’s camera and allow the light to gather photon by photon over a long period of time. The images are then computer enhanced to bring out the details the astronomers are interested in. In other words the pictures released by NASA are not what you would see if you actually looked into a telescope at the same object.

In astronomy time exposures can make dim objects brighter and allow objects that are invisible to become observable. (Credit: Photzy)

Another big difference between JWST and other telescopes, even the Hubble Space Telescope is that JWST views objects primarily in the infrared portion of the electromagnetic spectrum. This allows JWST to see details that are completely invisible to our eyes. That is the reason that JWST had to be placed more than a million kilometers from the Earth because the infrared light coming from both the Sun and the Earth would blind it if it weren’t protected. Again the digital images taken by the JWST in the infrared are then converted by a computer into visible images for astronomers, and the rest of us to see.

The difference between Hubble’s image of the Pillars of Creation in visible light (l) and the JWST image in the infrared is obvious. The dust that obscured Hubble’s image is gone in the JWST image allowing astronomers to actually see stars being born. (Credit: www.asc-csa.gc.ca)

The first set of images released from the JWST team at (John Hopkins Physics Lab) was of the well known ‘Whirlpool Galaxy’ often referred to as Messier 51 or just M51. At a distance of 27 million light years from Earth this galaxy is a favourite target of amateur astronomers not far from the Big Dipper in the sky. While M51 is a typical spiral galaxy it happens to be facing our galaxy almost head on so that our view of its spiral arms is simply magnificent. A very beautiful image of M51 was taken by Hubble a dozen years ago and astronomers have been itching to get a view with JWST ever since.

Hubble’s image of the Whirlpool galaxy only succeeded in making astronomers hungry for more. (Credit: ESA/Hubble)

Now they’ve done just that and the image is beyond expectations. One of the reasons JWST operates in the infrared is that infrared light can pass through the gas and dust that tends to blur the details in the spiral arms of galaxies like M51 in visible light. That means that JWST sees deeper into the galaxy, imaging structure never seen before. The same is also true of the small dwarf galaxy NGC 5195 located at the end of M51’s ‘tail’ and whose gravitational field is actually responsible for much of the structure of the Whirlpool’s spiral arms. Images such as JWST’s of the Whirlpool not only are beautiful but they give astrophysicists a lot of data to use in their efforts to understand how galaxies are structured and how they change with time.

JWST’s image of the center of the Whirlpool galaxy is simply breathtaking in its detail. (Credit: Mint)

The next astronomical object that the JWST team released images of was a lot closer to home, a mere 2,600 light years away. The Ring Nebula or M57 as it is known is located in the night sky near the bright star Vega and is in many ways a glimpse into the future fate of our own Sun. The star at the center of the ring was once about the same mass as our Sun but about a billion years ago it used up all of its hydrogen fuel and began to burn helium. In order to do that the star’s core had to get smaller and hotter which caused its outer regions to puff up making the star a ‘Red Giant’.

Probably the best known Red Giant is the star Betelgeuse in the constellation of Orion. The star is not only larger than our Sun it is actually larger than the orbit of Jupiter!!! (Credit: Brian Koberlein)

Then, less than a million years ago the star started to run out of helium so again its core got smaller and hotter, so much so that its outer regions were ejected from the star into interstellar space. This material was mostly ejected from the star’s equatorial region so it formed a ring around the original star, the Ring Nebula.

The JWST actually took two images of the Ring Nebula with its different instruments. On the right is the view from the Near Infrared NIRCam camera and on the left is from the Mid Infrared MIRI camera. (Credit: Prestige Online)

Since the ring itself is made up of gas and dust JWST’s ability to see in the infrared makes it the perfect instrument with which to study M57. The images taken by JWST show an enormous amount to detail that was never seen before including about 20,000 dense clumps of matter and a halo of 10 concentric arcs with 400 spikes. JWST also discovered that the central star causing the ring is not alone, it has two smaller companion stars, one about 35 astronomical units (AU) from the central star, an astronomical unit is Earth’s distance from our Sun, and the other more distant at 14,400 AU.

Because the distances in space are so huge astronomers use units like the Astronomical Unit, the average distance between the Earth and the Sun. (Credit: Study.com)

Like the images of the Whirlpool galaxy astrophysicists will have plenty to keep them busy analyzing what JWST has found at the Ring Nebula. Nebulas like the ring are not only important because they show our Sun’s future but also because the material ejected from such nebula is how heavier elements like Oxygen, Carbon, Nitrogen and Silicon get spread around the galaxy so that they can form planets like our Earth.

With the exception of Hydrogen and Helium all the other elements are manufactured inside stars. Planetary nebula like the ring nebula are one way those elements are released into the galaxy. (Credit: ZME Science)

The final set of images taken by JWST are of Supernova 1987A (SN1987A), the closest supernova to Earth in the last 400 years and the only supernova to date for which we have a picture of the star taken before it blew up. Supernova are rare events that only happen when a huge star, at least 20 times the mass of our Sun has used up all of the nuclear fuel available to it. When that happens the star’s core collapses into a neutron star or even a black hole. The rest of the star explodes in one of the most powerful events in the Universe.

Another comparison of Hubble (r) versus JWST (l). The greater detail in the JWST image is obvious. (Credit: Business Insider)

Obviously studying supernovas is a lot of fun but the problem is that they are so rare that detailed data is hard to get, most of the supernovas observed by astronomers are in galaxies billions of light years away. That’s why astronomers were so anxious for JWST to observe SN1987A. The Hubble space telescope had been observing the supernova for years and had watched as the shock wave from the explosion caught up to and slammed into material ejected from the star before it went nova.

The arrow in the top image points to the star that became the nova SN1987A. Bottom left is the star as it shined while going Nova and the bottom right is the JWST image today. (Credit: Reddit)

The images from JWST show that collision in even greater detail with a cluster of material that looks like a string of pearls. The JWST will continue to observe the dynamic changes around SN1987A while also searching for the neutron star that must have formed in the explosion but which so far has eluded detection.

An object as massive as the Sun but is only the size of a city is a neutron star. SN1987A should have formed such an object but we have yet to detect it. (Credit: Wikipedia)

The images released by the team (at Johns Hopkins) are just the beginning of the marvels that astronomers hope JWST will reveal in the years to come. Just as Hubble altered and illuminated our view of the Universe JWST is sure to do the same.

Astronomy News for October 2023: The James Webb Space Telescope begins to show off what it can do.

Lifted into orbit back in (December of 2021) the James Webb Space Telescope (JWST) spent its first months away from Earth calibrating its instruments while the world’s astronomers waited eagerly. Well JWST has been in operation for a little over a year now and NASA has taken the opportunity to release some of the more spectacular images sent back by the space telescope.

It may not look much like the telescopes we’re used to seeing but the James Webb Space Telescope (JWST) is the most powerful instrument ever for observing the Universe. (Credit:General Dynamics Mission Systems)

First a bit of a reminder, JWST operates as most large astronomical telescopes do by taking long exposure digital images of whatever astronomical object it is studying. Most of those ‘deep space’ objects are actually very dim and the only way to get good images is to open up the telescope’s camera and allow the light to gather photon by photon over a long period of time. The images are then computer enhanced to bring out the details the astronomers are interested in. In other words the pictures released by NASA are not what you would see if you actually looked into a telescope at the same object.

To the unaided eye the Milky Way is just a dim wisp of light across the night sky. But by taking a time exposure it becomes much more brilliant and impressive. (Credit: Dave Marrow Photography)

Another big difference between JWST and other telescopes, even the Hubble Space Telescope is that JWST views objects primarily in the infrared portion of the electromagnetic spectrum. This allows JWST to see details that are completely invisible to our eyes. That is the reason that JWST had to be placed more than a million kilometers from the Earth because the infrared light coming from both the Sun and the Earth would blind it if it weren’t protected. Again the digital images taken by the JWST in the infrared are then converted by a computer into visible images for astronomers, and the rest of us to see.

Infrared light, with longer wavelengths than visible light, is actually a much larger portion of the entire Electromagnetic spectrum than visible light is. (Credit: Study.com)

The first set of images released from the JWST team at John Hopkins Physics Lab was of the well known ‘Whirlpool Galaxy’ often referred to as Messier 51 or just M51. At a distance of 27 million light years from Earth this galaxy is a favourite target of amateur astronomers not far from the Big Dipper in the sky. While M51 is a typical spiral galaxy it happens to be facing our galaxy almost full on so that our view of its spiral arms is simply magnificent. A very beautiful image of M51 was taken by Hubble a dozen years ago and astronomers have been itching to get a view with JWST ever since.

A dozen years ago the Hubble space telescope took the image of the Whirlpool galaxy on the right. Now JWST has taken the image on the left. The increase in detail is obvious. (Credit: Business Insider)

Now they’ve done just that and the image is beyond expectations. One of the reasons JWST operates in the infrared is that infrared light can pass through the gas and dust that tends to blur the details in the spiral arms of galaxies like M51 in visible light. That means that JWST sees deeper into the galaxy, imaging structure never seen before. The same is also true of the small dwarf galaxy NGC 5195 located at the end of M51’s ‘tail’ and whose gravitational field is actually responsible for much of the structure of the Whirlpool’s spiral arms. Images such as JWST’s of the Whirlpool not only are beautiful but they give astrophysicists a lot of data to use in their efforts to understand how galaxies are structured and how they change with time.

The detail in this closeup of the JWST Whirlpool image can tell astrophysicists a lot about how galaxies are structured. (Credit: ESA/Webb)

The next astronomical object that the JWST team released images of was a lot closer to home, a mere 2,600 light years away. The Ring Nebula or M57 as it is known is located in the night sky near the bright star Vega and is in many ways a glimpse into the future fate of our own Sun. The star at the center of the ring was once about the same mass as our Sun but about a billion years ago it used up all of its hydrogen fuel and began to burn helium. In order to do that the star’s core had to get smaller and hotter which caused its outer regions to puff up making the star a ‘Red Giant’.

The Ring Nebula as seen by JWST. This is the most likely scenario for the eventual fate of our own Sun so as you might guess astronomers are very interested in all of the details. (Credit: Daily Express US)

Then, less than a million years ago the star started to run out of helium so again its core got smaller and hotter, so much so that its outer regions were pushed out from the star into interstellar space. This material was mostly ejected from the star’s equatorial region so it formed a ring around the original star, the Ring Nebula.

Stars spend about 90% of their life on the main sequence of the HR Diagram burning hydrogen. As they run out of hydrogen they begin to burn helium, becoming a red giant in the process. Eventually a star like our Sun will shed its outer layers, run out of helium and become a white dwarf. (Credit: Britannica)

Since the ring itself is made up of gas and dust JWST’s ability to see in the infrared makes it the perfect instrument with which to study M57. The images taken by JWST show an enormous amount to detail that was never seen before including about 20,000 dense clumps of matter and a halo of 10 concentric arcs with 400 spikes. JWST also discovered that the central star causing the ring is not alone, it has two smaller companion stars, one about 35 astronomical units (AU) from the central star, an astronomical unit is Earth’s distance from our Sun, and the other more distant at 14,400 AU.

Many star systems contain more than one star, our own Sun is actually in a minority. One of the few double stars systems that can be seen with the naked eye is in the Big Dipper, Mizar and Alcor. (Credit: Earthsky)

Like the images of the Whirlpool galaxy astrophysicists will have plenty to keep them busy analyzing what JWST has found at the Ring Nebula. Nebulas like the ring are not only important because they show our Sun’s future but also because the material ejected from such nebula is how heavier elements like Oxygen, Carbon, Nitrogen and Silicon get spread around the galaxy so that they can form planets like our Earth.

Carl Sagen liked to say that we were all made of star stuff and except for the hydrogen in your body all the other elements were made in stars. Objects like the Ring Nebula and supernova spread those elements throughout the galaxy so that they can form new planets and perhaps new life. (Credit: National Science Foundation)

The final set of images taken by JWST are of Supernova 1987A (SN1987A), the closest supernova to Earth in the last 400 years and the only supernova to date for which we have a picture of the star taken before it blew up. Supernova are rare events that only happen when a huge star, at least 20 times the mass of our Sun has used up all of the nuclear fuel available to it. When that happens the star’s core collapses into a neutron star or even a black hole. The rest of the star explodes in one of the most powerful events in the Universe.

The JWST image of supernova SN1987A. Only a very few stars are massive enough to explode the way this star did so there are only a few examples close enough for astronomers to study adequately. (Credit: Webb Space Telescope)

Obviously studying supernovas is a lot of fun but the problem is that they are so rare that detailed data is hard to get, most of the supernovas observed by astronomers are in galaxies billions of light years away. That’s why astronomers were so anxious for JWST to observe SN1987A. The Hubble space telescope had been observing the supernova for years and had watched as the shock wave from the explosion caught up to and slammed into material ejected from the star before it went nova.

Another comparison of Hubble (r) vs. Webb (l) of SN1987A. (Credit: Business Insider)

The images from JWST show that collision in even greater detail with a cluster of material that looks like a string of pearls. The JWST will continue to observe the dynamic changes around SN1987A while also searching for the neutron star that must have formed in the explosion but which so far has eluded detection.

It is thought that the Neutron Star left over after a supernova event becomes a Pulsar beaming radio waves like a lighthouse. If the beams aren’t pointed at you a Pulsar can be difficult to detect however and that seems to be the case with SN1987A. (Credit: aether.lbl.gov)

The images released by the team (at Johns Hopkins) are just the beginning of the marvels that astronomers hope JWST will reveal in the years to come. Just as Hubble altered and illuminated our view of the Universe JWST is sure to do the same.

Bit by bit Astronomers are learning the secrets of the massive stellar explosions called Supernovas, even if they do occasionally come across evidence that doesn’t fit their theories.

Everyone has heard a little bit about Supernovas, you know those stars who destroy themselves in explosions that for a few weeks can outshine many billions of normal stars. Supernovas are very rare events, happening only every couple hundred years in our galaxy of one hundred billion stars. In fact supernovas are so rare that most of what we’ve learned about them comes from observing ones that happen in other galaxies. It works like this, if supernova only occur once every 100 years per big galaxy then if you keep an eye on 1,000 galaxies you should see about 10 a year!

Three images, taken on successive nights, of the Galaxy M101. On August 22 (l) there was no supernova, green arrow shows location. SN2011fe was discovered on the night of the 23rd (m) while by the night of the 24th (r) it was considerably brighter. By keeping an eye on a thousand such galaxies astronomers manage to observe a dozen or so supernova ever year. (Credit: Space.com)

The very first studies of supernovas, conducted more than 70 years ago now, used spectral analysis to show that there were two basic types. One type, not surprisingly called Type 1, had virtually no hydrogen in the spectra obtained from their light. Now hydrogen is the most common element in the Universe so for Type 1 supernovas to be completely lacking in it is really significant. Type 2 supernovas are just the opposite, their spectra shows plenty of hydrogen. One thing both types have in common is that they are very rare which indicates that only a small percentage of stars ever go supernova.

In time astrophysicists came up with two rather different models of supernovas. Type 1 begin with a white dwarf, the superdense corpse of a once normal star, for example our Sun will become a white dwarf in about 6-7 billion years when it runs out of its hydrogen fuel. A typical white dwarf has a mass about that of our Sun but its size is only that of the Earth. The surfaces of dwarfs are extremely hot but because of their small size they are much dimmer than a normal star like our Sun.

If a white dwarf star steals mass from a companion star it can grow too massive leading to a collapse that triggers a Type 1 Supernova. (Credit: Phys.org)

Now if a white dwarf happens to have a companion star, and there are many examples of binary star systems, the dwarf can start pulling material away from its companion. This stealing of matter can only go on so long however because there is a maximum limit to the mass of a white dwarf. This maximum mass is about 1.4 times the mass of our Sun and if a dwarf exceeds this limit it begins to collapse triggering the Type 1 supernova. After the explosion all that’s left of the star is a neutron star or even a black hole.

The famous Crab Nebula M1 is the remains of a Type 2 Supernova. At the center of the nebula is a neutron star that emits radio signals as a pulsar. (Credit: Wikipedia)

Type 2 supernova however start as huge, very massive stars, at least ten times the mass of the Sun. The fusion reactions in such stars use up their hydrogen fuel in only a few million years. The star will then begin to fuse helium into carbon and oxygen, which is as far as our Sun will ever get. Massive stars however have enough energy to keep going, fusing carbon and oxygen into heavier elements all the way up to iron.

The supermassive star Eta Carinae, seen here in an image from Hubble, is destined to explode in a few million years as a Type 2 supernova. (Credit: Medium)

Iron is a brick wall however, fusing iron into a heavier element doesn’t produce energy it consumes it. The fusion reactor of this huge, massive, intensely hot star suddenly comes to a screeching halt and the star begins to collapse upon itself. This collapse triggers the supernova but unlike a Type 1 supernova there is still some hydrogen left in the star’s outermost regions, which shows up in the explosion’s spectra. After the explosion all that remains of the star is a neutron star or black hole.

Nuclear binding energy per nucleon. Nuclei that are less massive than iron can be fused to produce energy while more massive than iron can be split to produce energy. Whatever you do to iron however will require energy. (Credit: Conceptual Physics)

Those are the theories, but to be certain they’re right we would have to observe a star before it goes supernova and that’s not an easy thing to do. After all there are literally trillions of stars in our galaxy and nearby ones, while only a couple of dozen of those stars will go supernova each year. The question is then, which ones? Well what astronomers have tried to do is to get observations of as many stars as possible. Then when a supernova does occur they check their archives to see if they have any prior images of it.

The star Sanduleak -69degrees 202 (r) before it exploded as SN1987A (l). This was the first time astronomers were able to identify the progenitor star to a supernova. (Credit: David Malin, Anglo-Australian Observatory)

The first time that this technique worked was the Type 2 Supernova SN 1987A, in the Large Magellanic Cloud, which is a satellite galaxy orbiting the Milky Way. Almost as soon as SN 1987A was detected astronomers quickly began looking through their past observations and succeeded in finding a few observations of the star, catalog name SK-69º202 before it exploded. Although there were a few surprises SK-69º202 turned out to be pretty much what astronomers had expected, with 15 times the mass of our Sun and a very hot surface. The data gained from SN1987A taught astrophysicists a great deal about Type 2 supernovas, but of course they wanted more, and in particular, they wanted a Type 1 supernova progenitor.

SN 2019yvr in the galaxy NGC 4666 at a distance of 46 million light years. (Credit: Remote astrophotography using Slooh.com)

Now they may have one, and it’s not what they expected. Back in December of 2019 astronomers spotted a supernova, designated SN 2019yvr in the galaxy NGC 4666 which is about 46 million light years away in the Virgo super cluster of galaxies. Even as observations were showing that SN 2019yvr was a Type 1 supernova astronomers associated with the Hubble Space Telescope were rummaging through earlier images of NGC 4666 to try to see if Hubble had ever made any observations of the star.

The Hubble space telescope has made many discoveries during its lifespan. The image of the progenitor star for SN2019yvr may be its latest. (Credit: Science Focus)

The astronomers spent more than a year of checking and crosschecking between the measurements made after the supernova began to those that had been taken earlier. Nevertheless they think they may have found the supernova’s progenitor in a series of images taken some 2.6 years before the explosion, problem is, the star they’ve identified is not the kind the theory says it should be.

Instead of a tiny, dense, extremely hot white dwarf the star that’s been identified is a fairly cool orange-yellow star more than 300 times the width of our Sun. A star like that should have plenty of hydrogen left in it but the spectra of the supernova showed none, it’s just a mystery.

The type of star Hubble found however appears to be an Orange ‘K’ type star shown here with a larger ‘G’ type star, our Sun, and a smaller red ‘M’ type star. (Credit: EarthSky)

The astronomers have already come up with several explanations for the disagreement with the theory. First of all they could simply have identified the wrong star. They can’t check to make certain right now because the debris of the supernova is currently obscuring that region of space and it will take 5-10 years before they are able to see if the orange-yellow star is still there.

The expanding debris field of SN1987A makes it difficult to observe the remaining neutron star at the center. (Credit: CEA-Irfu)

Then there’s also the possibility that the companion star, remember Type 1 supernovas require a companion star, could have given off enough material to form a cool gaseous shroud around a white dwarf that was the actual supernova progenitor. Again checking this possibility will have to wait for the debris to clear a good deal.

Of course there’s also the possibility that our theories are just wrong and have to be adjusted. Whichever possibility turns out to be true astronomers are bit by bit learning the secrets of what are some of the most spectacular events in the Universe, Supernovas.