A hot and rocky exoplanet known as a super-Earth has been discovered orbiting one of the oldest stars in our Milky Way galaxy, according to a new study.
The exoplanet, called that because it’s located outside our solar system, is about 50% larger than Earth and has three times the mass — which makes it a super-Earth by astronomy standards.
Even so, the planet, known as TOI-561b, only takes less than half an Earth day to complete one orbit around its host star.
“For every day you’re on Earth, this planet orbits its star twice,” said Stephen Kane, study coauthor and astrophysicist at the University of California, Riverside, in a statement.
The study has been accepted for publication in the The Astronomical Journal and was presented Monday at the 237th meeting of the American Astronomical Society, which is occurring virtually due to the pandemic.
This super-Earth’s proximity to its host star creates an average surface temperature on the planet exceeding 2,000 Kelvin, or 3,140 degrees Fahrenheit.
The planet was discovered using NASA’s planet-hunting TESS mission, which launched in 2018. The name “TESS” is short for Transiting Exoplanet Survey Satellite. The mission regularly surveys parts of the sky and observes nearby stars to determine if there are planets orbiting them.
The astronomers found TOI-561b — “TOI” is short for TESS Object of Interest — in the thick galactic disk of the Milky Way. This rare population of stars is known for having less heavy elements, like iron or magnesium, than are often associated with planet creation.
To confirm their finding, the researchers used the W.M. Keck Observatory in Hawaii and were able to determine the planet’s mass, radius and density.
Astronomers, however, were surprised to discover that despite the planet’s mass, its density is about the same as that of Earth.
“This is surprising because you’d expect the density to be higher,” Kane said. “This is consistent with the notion that the planet is extremely old.”
Older planets are actually less dense because there weren’t as many heavy elements present in the universe when these planets formed. Heavy elements are created as stars age and explode — which seeds the creation of new stars and planets across the universe.
“TOI-561b is one of the oldest rocky planets yet discovered,” said lead study author Lauren Weiss, a University of Hawai’i postdoctoral fellow, in a statement. “Its existence shows that the universe has been forming rocky planets almost since its inception 14 billion years ago.”
There are also two additional planets orbiting the star, both of which are larger and likely gaseous.
The Milky Way galaxy was likely formed 12 billion years ago. This star and its planets are 10 billion years old — while our sun is only 4.5 billion years old.
“This planet formed at a time when the majority of stars in our galaxy were first beginning to shine,” Weiss said at the conference on Monday.
Understanding the planet’s mass and radius allow astronomers to learn more about its internal structure.
“Information about a planet’s interior gives us a sense of whether the surface of the planet is habitable by life as we know it,” Kane said. “Though this particular planet is unlikely to be inhabited today, it may be a harbinger of many rocky worlds yet to be discovered around our galaxy’s oldest stars.”
Even though TOI-561b is a rocky, or terrestrial planet, like Earth, it’s far too hot to support life. But given that this rocky planet is so old, and the first confirmed rocky planet around such an old star, astronomers wonder if the planet was habitable at some point in the past.
And if it was, whoever lived there would have had a wonderful view.
Stars in the thick galactic disk “have motions that take them high above and far below the plane of the galaxy, providing them with what might be stunning views, if anyone were there to see them,” Weiss said.
In Photos: Hubble Captures Echoes Of Violent Supernova ‘Fireworks’ That Lit-Up Night Sky In The Third Century – Forbes
The Hubble Space Telescope has captured light from a supernova blast—an exploding star—that would have been seen from Earth 1,700 years ago.
Although there are no known records of anyone seeing it, a cosmic explosion that’s been compared to fireworks would have been visible to people in Earth’s southern hemisphere.
It’s now visible to the Hubble Space telescope as a delicate greenish-blue shell—a supernova remnant (SNR)—in a nearby galaxy to the Milky Way called the Small Magellanic Cloud (SMC).
The SNR is called 1E0102.2-7219, or E0102 for short. Here’s everything you need to know about how Hubble’s spectacular images have been used to precisely date an incredible supernova explosion.
What and where is E0102?
E0102 is the leftovers of a massive explosion of a star in a nearby dwarf galaxy—the SMC.
The images from Hubble show the aftermath of a supernova—the dissipating energy has created a spectacular display of greenish-blue filaments.
The above image of part of the SMC shows that E0102 is “close”—about 50 light-years—from a massive star-forming region of glowing hydrogen emission called N 76 and Henize. You can see that as the pink-ish section in the upper-right of the image. E0102 is at the center of the image.
What do we know about the star?
Not much, though it may have been a Wolf-Rayet star—a very large and old star made from heavy elements that had probably blown-off its hydrogen before the explosion.
Astronomers think that because the colors of E0102 indicate that it was rich in oxygen rather than hydrogen and helium.
How did astronomers use Hubble’s images?
Although E0102 was previously known about, its age was unknown. Treating E0102 as forensic evidence, astronomers used Hubble’s observations of E0102 taken a decade apart to calculate the cloud’s expansion rate.
They did that by calculating how fast 22 separate oxygen-rich knots of debris in the SNR had moved in 10 years. They then traced it back to the point in space where the progenitor star must have exploded.
Why Hubble’s longevity was so crucial
“A prior study compared images taken years apart with two different cameras on Hubble, the Wide Field Planetary Camera 2 and the Advanced Camera for Surveys (ACS),” said Danny Milisavljevic of Purdue University in West Lafayette, Indiana, one of the leaders of the research team whose paper was presented yesterday at the 237th meeting of the American Astronomical Society.
“But our study compares data taken with the same camera, the ACS, making the comparison much more robust; the knots were much easier to track using the same instrument,” he said.
“It’s a testament to the longevity of Hubble that we could do such a clean comparison of images taken 10 years apart.”
What is the SMC?
The Small Magellanic Cloud is a satellite galaxy of our Milky Way. It’s about 200,000 light-years away in the constellation Tucana. It’s really easy to see in the night skies in the southern hemisphere.
Wishing you clear skies and wide eyes.
Creation by catastrophe – Skywatching – Castanet.net
Collision of the Galaxies sounds like a good title for a spectacular disaster movie.
Actually, a lot of things in the universe depend on things smashing together, including galaxies. The object
Arp 299 is two galaxies in collision.
The two, designated NGC 3690 and IC 694, lying about 134 million light years away from us, have been in the process of collision for around 700 million years. The Hubble Space Telescope image can be found at https://en.wikipedia.org/wiki/Arp_299. The image is dotted with many bright, blue stars.
This is interesting because there are only two types of bright, blue star. One kind are young stars that will dim down a bit as they settle down.
The other kind are stars that collected an exceptionally large amount of hydrogen when they formed. These stars shine extremely brightly, run out of fuel soon, collapse and then explode. These explosions are called supernovae.
In either case, these blue stars cannot be very old. This relates to another interesting aspect of this pair of galaxies: the oddly large number of supernova explosions. What has produced these unusual circumstances?
If you look at a nearby spiral galaxy, such as our close neighbour, the Andromeda Galaxy, you will see the spiral arms glowing with little knots of pink, and sparkling with young stars.
If we could go a couple of million light years off into space, our galaxy, the Milky Way, would look much the same. The reason is that the spiral arms of galaxies are loaded with hydrogen gas, the primary ingredient for making stars.
If we look closer, we will see that these clouds are not uniform; some regions are much denser than others. On occasion, something triggers one of these denser regions to collapse, forming one or more stars.
These youngsters are hot and blue, and their high output of ultraviolet radiation makes the surrounding clouds glow pink. This pink, a characteristic of hydrogen, is known as hydrogen-alpha emission.
Therefore, when we look at a distant galaxy, those pink glows mean two things:
- There is hydrogen to glow
- Hot, blue stars to make it glow.
However, the jewel-box of bright, blue stars we see in the Arp 299 pair of galaxies is really unusual. Some major event caused massive collapses of hydrogen clouds, forming showers of new stars. We are pretty sure this outburst of star formation was caused by the two galaxies colliding.
Paradoxically, collisions between galaxies are not totally catastrophic; they trigger the formation of new stars and planets.
When we look at the computer simulations of collisions between galaxies (there are many on the web), they look pretty catastrophic. One can imagine stars and planets being annihilated on a huge scale.
The youtube on this link is a good example of what we believe a collision between two galaxies would look like. However, the situation is nothing like as bad as it looks.
The nearest star to us, after the Sun, lies about four light years away. This distance is fairly typical of the average distance between stars. So the chance of stars in two colliding galaxies passing close to one another is tiny. Even as fragments fly around and the galaxies combine, all the inhabitants of worlds in those galaxies will see is their equivalent of the Milky Way changing shape over millions of years.
However, for the gas clouds between the stars it’s a different matter. These will collide and collapse, forming lots of new stars.
We will get a chance to experience this first hand. The Milky Way and the Andromeda Galaxy are racing toward each other at 110 km/s, and will collide in about four billion years. There are computer simulations of this collision on the web.
- The only easily visible planet is Mars, which can be found high in the southwest during the evening.
- The Moon will reach First Quarter on the 20th.
Oldest quasar and supermassive black hole discovered in the distant universe – CTV News
The most distant quasar and the earliest known supermassive black hole have been discovered, shedding light on how massive galaxies formed in the early universe.
This discovery was revealed Tuesday at the 237th meeting of The American Astronomical Society, happening virtually due to the pandemic. The study has been accepted for publication in the Astrophysical Journal Letters.
A quasar, or quasi-stellar object, is the compact region at the center of a galaxy that throws off enormous energy. They emit so much energy that quasars appear like stars through a telescope. Astronomers believe that the supermassive black holes at the centers of galaxies actually power quasars, acting like an engine.
When gas falls into quasars at the centers of galaxies, they form disks of gas and dust that emit electromagnetic energy. This creates a brightness greater than entire galaxies.
Jets shoot out of the quasar, pulsing with X-rays, and they are some of the hottest things in the entire universe. The jets blow gas and dust, which are essential to form stars, out of the galaxy. When a quasar forms, it signals the end of a galaxy’s star-forming days.
This quasar is a thousand times more luminous than our Milky Way galaxy, and it’s powered by the earliest known supermassive black hole. The light from this quasar took more than 13 billion years to reach Earth, and astronomers were able to observe it as the quasar appeared just 670 million years after the Big Bang.
Its black hole engine weighs more than 1.6 billion times the mass of our sun, making it twice as massive as that of the previous record holder.
“This is the earliest evidence of how a supermassive black hole is affecting the galaxy around it,” said Feige Wang, lead study author and NASA Hubble fellow at the University of Arizona, in a statement. “From observations of less distant galaxies, we know that this has to happen, but we have never seen it happening so early in the Universe.”
The quasar has been dubbed J0313-1806 by the astronomers who discovered it.
“The most distant quasars are crucial for understanding how the earliest black holes formed and for understanding cosmic reionization — the last major phase transition of our Universe,” said Xiaohui Fan, study coauthor and regents professor of astronomy at the University of Arizona, in a statement.
To picture the brightness of this highly energetic object, imagine our sun — but 10 trillion times more luminous.
Astronomers were surprised to discover this quasar was fully formed in such a short time, astronomically speaking, after the Big Bang. The presence of the massive black hole that powers it at this early point in the universe’s timeline also challenges how astronomers understand black hole formation.
For example, how did this black hole have time to form?
“Black holes created by the very first massive stars could not have grown this large in only a few hundred million years,” Wang said.
Typically, such massive black holes form when giant stars explode and collapse, forming black holes that grow in size. They can also form when a dense cluster of stars collapses. Both of these take time.
“This tells you that no matter what you do, the seed of this black hole must have formed by a different mechanism,” Fan said. “In this case, it’s a mechanism that involves vast quantities of primordial, cold hydrogen gas directly collapsing into a seed black hole.”
The brightness of the quasar indicates that the black hole is gobbling up about 25 stars like our sun each year, which powers an outflow of gas moving at 20% the speed of light.
This loss of gas typically halts the birth of stars in a galaxy because that gas is a necessary ingredient in star formation.
“We think those supermassive black holes were the reason why many of the big galaxies stopped forming stars at some point,” Fan said.
Ultimately, the black hole will eventually run out of food, stunting its growth, Fan said.
Multiple telescopes were used in the discovery and astronomers are eager to observe it more in the future.
The galaxy that hosts the quasar is rapidly producing stars at a rate that is 200 times faster than the Milky Way.
“This would be a great target to investigate the formation of the earliest supermassive black holes,” Wang said. “We also hope to learn more about the effect of quasar outflows on their host galaxy — as well as to learn how the most massive galaxies formed in the early Universe.”
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