#red dwarfs

[zespaceblog]

The Mystery of TOI-4860

How planets form is by no means an exact science, there's a general agreed framework, but even this occasionally falls foul of actual observations, and that's what happened when scientists actually went out looking for model breaking examples.

In this case, the theory suggests that small low mass stars can't have had enough material to create large gas giants, as most of the gas would have ran out in the creation of the star, however TOI-4860b begs to differ, a super Jupiter type planet almost one third of the mass of the host star puzzles the team in quite how it got there.

It's possible of course that such a large planet was captured somehow, but investigation into the planets makeup has shown it's high in metallicity, as is the star itself, so it looks like both were made from the same accretion disk.

The scientists involve suspect the high metallicity could be the clue, that in some way this has accelerated the process of forming gas giants where otherwise it would not have occurred.

If this is true, it could add a new dimension to the model of planet formation, and hint at new processes that ultimately lead to Jupiter type planets. Of course, one planet/star doesn't make a theory, but the team will continue their work looking at such scenarios to strengthen the evidence for such a mechanism.

[merelygifted]

Hubble telescope sees an angry star and an evaporating planet | Space

[cosmicfunnies]

Starry Greetings!

The finale of Sparkly Stars is here!

This week’s comic: Red Dwarfs

https://www.space.com/23772-red-dwarf-stars.html

[zespaceblog]

YZ Ceti b

No actual image of YZ Ceti b exists, but we human's like to imagine what it could be, hence the artists impression above.

What we do know is it's a planet around .7 times the mass of Earth, that orbits every 2 days around a the Red Dwarf YZ Ceti, located just 12 light years from us, in the constellation of Cetus (as it's name suggests).

As a small Red Dwarf star, it's not visible with the naked eye, and prone to periodic outbursts, huge flares that would quickly strip most planets of any vestige of an atmosphere.

However, recent observations by VLA has noticed radio waves being emitted from the star itself, and although the team working on this haven't yet confirmed the cause, one possible option is that YZ Ceti b has a magnetic field that's causing the star to exhibit odd aurora events, similar to how Earth's magnetic fields channel charged particles when it's bombarded too.

Magnetic fields are assumed to be a key component of planets that are able to keep their atmosphere, but more so, they offer life a rest-bite from the onslaught of charged particles.

YZ Ceti b is far too hot for life (as we know it at least) but it may point to interesting ways we may be able to detect magnetic fields orbiting more likely candidates for life, so in that respect, this is a very interesting find, if it turns out to be what is theorised.

[zespaceblog]

Hycean Class Planets

In the search for life, went tend to look for the rather cringably termed "Earth 2.0", the small rocky planet in the habitable zone that could sustain liquid water, and we've found a fair number of these planets to date, but their size and proximity to their host star makes detailed readings very challenging.

A much more common find however are super-Earth's or sub-Neptune sized planets, generally overlooked for life on the basis the gravity would be far too extreme and the surface likely blanketed by a thick atmosphere similar to Venus that would both heat and crush any macro life at the very least.

However, Astronomers at the University of Cambridge UK think they may have come up with a more common and easier place to look, what they have termed the "Hycean World".

These classes of planets are 2.5 times the mass of the Earth and over, have atmosphere's of hydrogen and huge oceans of water on the surface. The atmospheric temperature and gravity would be too harsh for land based life as we know it, but under the water there certainly could be conditions for life to thrive.

The astronomers believe it may be easier to pick up on the traces of life in the atmosphere of these larger planets than trying to find biosignatures on smaller rocky planets, and have already identified a good number orbiting red dwarf stars within 150 light years of Earth.

One such exoplanet is the K2-18b, 111 light years away in the constellation of Leo and with a red dwarf star. The planet is 6 times the mass of Earth and sitting in the habitable zone of the star. Scientists think the planet is either mostly a rocky word with an atmosphere similar to Earth but FAR larger, or most likely, a water/ice world with a much thicker atmosphere.

Source : http://www.sci-news.com/astronomy/hycean-worlds-10004.html

http://www.sci-news.com/astronomy/red-dwarf-k2-18-two-super-earth-sized-exoplanets-05504.html

[zespaceblog]

NGC 5907 - Knife Edge Galaxy

50 Million light years from Earth in the constellation of Draco, this edge on Spiral galaxy is a bit of a mystery. The stars inside of it have very low metallicity, meaning they were created from a source of very pure hydrogen/helium, similar to what existed near to the big bang. This is often associated with very old objects, near to 11-12 Billion years old. Closer examination appears to show the galaxy has very few if any giant stars, most being dwarf stars, that are incredibly long lived (red dwarfs could theoretically last trillions of years).

Further more, more recent observations revealed a looping stream of stars and gas, following a tidal pattern which appears to show some interaction earlier in the galaxies existence. 

The mechanisms involved that decide the size of the stars are not fully understood, so an entire galaxy of dwarf stars is quite a puzzle, not one we know to be replicated to this extent elsewhere. 

One upshot of this is, that if the galaxy doesn’t interact with any others in the future, it’s likely to be among the last galaxies left standing, long after all other galaxies have been consumed by their central black holes, the dwarf stars will continue shining for billions more years before finally collapsing to white dwarfs or for the smallest of red dwarfs, a blue dwarf. 

[zespaceblog]

Red Dwarfs and Life

Red Dwarf stars are the most common kind of star and the longest lived of the main sequence stars. A long life for a star means longer time for life to get going, and since we’ve started finding exoplanets circling fairly commonly in the habitable zones, they’ve become more interesting over time. 

However, an old concern never went away, Red Dwarf stars are also prone to intense outbursts of radiation and charged particles. What we think of as Solar wind, Red Dwarfs create solar Tsunami’s, and very regularly. 

This means, planets close in, in that habitable zone, are exposed to intense and regular blasts of radiation, not just making life unlikely, but even atmospheres around such planets.

One hope had been that older Red Dwarfs may offer a better environment, as over time, these stars do begin to calm down a little, but by how much ? 

A study of Barnards Star, a red dwarf 6 light years from us, has found significant outbursts are still common, making the likelihood of life much lower.

What isn’t known is how much Barnards star represents the other similarly aged red dwarf population, so further study is required, but it does appear to be confirming the earlier fears that these stars may not be the best place to look for life, or at least, life under the kind of environment we know.

Source : 

https://astronomynow.com/2020/10/30/red-dwarfs-may-be-more-hazardous-to-ones-health-than-previously-thought/