Astronomy News

[Halbhh]

This whole question about how much previously-undetected stellar variability/flares is there is only lately getting going really (in a more intensive way), and it's early in the process of answering.

Another accessible and informative little news article has a nutshell bit about why it matters, and also a snapshot of the ongoing search --
Mini-flares potentially jeopardize habitability of planets circling red dwarf stars

 

[FrumiousBandersnatch]

That was actually a hand-waving hypothetical sentence. Notably hopeful.

Thanks - good to have a direct report from someone who was there...

 

[Halbhh]

Thanks - good to have a direct report from someone who was there...

See #41 for why.

 

[FrumiousBandersnatch]

See #41 for why.

Yes, I saw that - but I don't think it's quantitative enough to justify your critique.

 

[Halbhh]

Yes, I saw that - but I don't think it's quantitative enough to justify your critique.

It's simply that we don't actually know what % of red dwarfs are quiet if any, and it's only hypothesis that some are, and it looks like that hypothesis (that some % are quiet, not flaring too much to allow liquid water zone planets that have land and water both to be able to maintain favorable conditions for life as we know it) is likely to fail, because we didn't have sufficient observation yet (sufficient combing through data), and that is going to change. It's pure guessing either way. I'll rely not on guesses long, but instead on the data, over time. Just giving you a heads up that that hypothesis looks vulnerable to being shot down.

 

[Shemjaza]

Yes, in our imaginations. I say that from reading many thousands of astronomy articles. For instance, this was interesting yesterday:
https://phys.org/news/2018-04-amazingly-wide-variety-disks.html
You'll want to see these interesting images on a larger screen, or at least clicking on them if using a phone.

Only in our imagination, for now. I hope humanity lasts long enough for the lifetime of stars to be relevant to our civilisation.

Planetary systems are rather more highly individual than we used to think. Also, the planets tend to migrate unless they can get an unusual stable configuration. To be protected from bombardment for instance it helps a smaller rocky planet like Earth (a planet able to have both land and water and pleasant and very useful margins between the two) to have a gas giant to help protect it against too much asteroid bombardment. But a gas giant will cause a small planet to migrate. Why doesn't Earth? Because we have an unusual combination of 4 gas giants of favorable mass ratios and orbits. A variety of stars in addition to red dwarfs are non-quiet, and even a sun sized star isn't necessarily quiet. Ergo, conditions favorable to the evolution of life (as compared to a brief existence then extinction) as we know it is likely to be rather a lot more rare than people imagine in popular science articles in the last many years. Often when you read in popular science articles you are reading a combination of a bit of observation and a lot of extra added imagination. Another new factor I just noticed the other day is that it helps if one hopes to have both water and land and margins to have only a little water, but not much, and then you have to have the magnetic field that is adequate to protect that water from solar flux dissociation over time, so here we have a combo of a nicely strong magnetic field, a quiet star, a nice distance, just the right amount of water and plate tectonics, a helpful moon of a nice size, a very nice combination of gas giants. Rather a nice locale. I didn't make an exhaustive list there, but these are the most key things off the top of my head.

I'll certainly grant that Earth is in pretty nice spot, and the odds of something similar nearby is vanishingly small, but the scale of universe makes the supremely improbable, just a matter of time.

 

[Halbhh]

Only in our imagination, for now. I hope humanity lasts long enough for the lifetime of stars to be relevant to our civilisation.

I'll certainly grant that Earth is in pretty nice spot, and the odds of something similar nearby is vanishingly small, but the scale of universe makes the supremely improbable, just a matter of time.

That's the classic article of faith on this, and I've generally expected it. While I think it's highly likely that life arises commonly, commonplace, and is then extinguished, over and over, my guessing is that there will be some other star systems where a planet is more favorable to get past just a couple of billion years of life without one of those dozen(s) of common processes that extinguish it. How many though? heh, there's the question alright. What if the actual number in the Milky Way of life evolving onto land and continuing past 2 billion years is....one? We don't know yet, but my guess is a planet needs a Protector (heh, Larry Niven used an idea akin to that in a fun series of stories, the Pak Protectors if I remember right)

 

[FrumiousBandersnatch]

Just giving you a heads up that that hypothesis looks vulnerable to being shot down.

OK, no problem.

 

[Halbhh]

https://phys.org/news/2018-04-stars-dna-interrogated-sun-lost.html

A chance to find stars born from the same area as our sun (assuming that cluster/area was fairly homogeneous). What if they are able to find not only a 'sibling' but also one of the same mass? :=) would be fun.

 

[Ophiolite]

https://phys.org/news/2018-04-stars-dna-interrogated-sun-lost.html

A chance to find stars born from the same area as our sun (assuming that cluster/area was fairly homogeneous). What if they are able to find not only a 'sibling' but also one of the same mass? :=) would be fun.

Interesting, but with this caveat. The number of stars in the galaxy is estimated to be at least 100 billion. This project will sample 1 million of them. That is a mere 0.001% of the total. I'm not convinced we will necessarily find even a single sibling amongst that sample.

 

[Halbhh]

Interesting, but with this caveat. The number of stars in the galaxy is estimated to be at least 100 billion. This project will sample 1 million of them. That is a mere 0.001% of the total. I'm not convinced we will necessarily find even a single sibling amongst that sample.

It's an interesting question because 5 billion years is really a long time, lol, and even a modest amount of different velocity really adds up a lot over a billion years, lol. Let me do a very quick and dirty calculation, just to get some sense of some vague near order of magnitude (like +/- 1 order of magnitude from a realistic one hopefully). We know the idea is the cluster was ripped apart by ordinary dwelling in the Milky Way (meaning by at-distance but still near enough encounters with other stars passing by with various relative velocities)... First looking at typical velocities and velocity groupings: Stellar kinematics - Wikipedia

....

Ok, having read and also thought on it, and using also my fun experiences with Universal Sandbox^2 (on my PC, available via "Steam", which is a new version, advanced and fun, of what I once did far simpler myself on my own Apple II+ in the early 80s -- actual equations to realistically simulate orbiting bodies)... I think not only are the various changing (thus new) velocities of the stars of a dissociating open cluster truly random, but there's not any point in guessing what portion if any might continue together roughly as a stellar association, " gravitationally unbound and are still moving together through space". The idea I saw is that the sun being 5 bn years old means any association it was with has been dispersed long ago (though one could try to dig deeper if you want on this aspect). Rather wait for the results of this combing of the data to just see. Because the new random velocities given by random encounters will be all quite random, and not even have a simple limited range of a few orders of magnitude, and also gravitationally meaningful encounters will be multiple over time likely on that time scale, so it's all truly randomized to a high degree I'm thinking. Our sun could have been itself possibly moved away with a higher than average amount of encounters. So a order of magnitude guess even within 3 orders of magnitude is only hand waving. Still, that's like (quick and dirty) using a hypothetical figure (quick and dirty) that stars may have a typical variation like near the order of 5 km/sec (using 1 or 10 km/sec as a thinking about it order of magnitude guess), even with that after 3 billion years you have something big like for instance on the order of 50,000 light years from 5km/sec for 3 bn years. So, for instance 5,000 light years is pretty far away, and that would include something one site thinks is 600 million stars for instance. I could not resist just wanting a feel for some possibility. Could 5 km/sec be an order of magnitude too high for an average differing velocity between stars from the original cluster -- don't know that answer with this quick and dirty look. But that kind of thing could be guessed at better statistically with a statistically valid large sample of relative velocities.

Consider though the Sun! The "peculiar motion of the Sun" isn't down around just 5km/sec, but a fair bit more -- more than twice that --
Stellar kinematics - Wikipedia

 

[Halbhh]

OK, no problem.

Notice the wording in this news -- "not predicted" :

"Astronomers using NASA's Swift satellite spotted a massive solar flare coming from a tiny star on April 23. The explosion was over 10,000 times more intense than anything that has been recorded from our Sun.
The star, DG CVn, is an M class star located about 26 light years away in the constellation Canes Venatici. Its radius and mass are about a third of that of our Sun and it's about 1/1000 less luminous. DG CVn is a young star at only about 35 million years old, and like most young stars, it spins rather quickly. While this spinning does contribute to an increased level of activity, DG CVn's flares surpass anything astronomers had predicted.

"We used to think major flaring episodes from red dwarfs lasted no more than a day, but Swift detected at least seven powerful eruptions over a period of about two weeks," ...
Dwarf Star Emits Solar Flare 10,000 Times Stronger Than Anything Seen From Our Sun

This is what I notice so many times now: more flares then predicted, bigger than expected, etc. Report after report showing unexpected results.

 

[FrumiousBandersnatch]

Notice the wording in this news -- "not predicted" :

"Astronomers using NASA's Swift satellite spotted a massive solar flare coming from a tiny star on April 23. The explosion was over 10,000 times more intense than anything that has been recorded from our Sun.
The star, DG CVn, is an M class star located about 26 light years away in the constellation Canes Venatici. Its radius and mass are about a third of that of our Sun and it's about 1/1000 less luminous. DG CVn is a young star at only about 35 million years old, and like most young stars, it spins rather quickly. While this spinning does contribute to an increased level of activity, DG CVn's flares surpass anything astronomers had predicted.

"We used to think major flaring episodes from red dwarfs lasted no more than a day, but Swift detected at least seven powerful eruptions over a period of about two weeks," ...
Dwarf Star Emits Solar Flare 10,000 Times Stronger Than Anything Seen From Our Sun

This is what I notice so many times now: more flares then predicted, bigger than expected, etc. Report after report showing unexpected results.

Sure, I saw that. I am just wary of extrapolating unexpected results from a single star to red dwarfs in general.

 

[Halbhh]

Sure, I saw that. I am just wary of extrapolating unexpected results from a single star to red dwarfs in general.

Totally agree. Just in case I was not clear enough -- I've read various news on various stars flaring, more often and/or bigger than predicted, surprising the observers, different stars, probably about 10-15 instances in the last few years. It's not enough to conclude anything except that clearly systematic searches for flares (such as that one above we already discussed a bit) are indicated. It's all just suggestive there may be a lot to learn about flare activity for a variety of common stars.

 

[Halbhh]

Sure, I saw that. I am just wary of extrapolating unexpected results from a single star to red dwarfs in general.

Look also at this new article for what I call hopeful hand waving (imagination? Or more a sort of faith attitude I think)

Look at the first paragraph under A closer look at the TRAPPIST-1 planets (actually ending in an exclamation point heh heh; they are excited for any planet not desiccated by flares and ordinary solar wind)

https://phys.org/news/2018-04-astronomers-earth-like-planets-capable-hosting.html

...Even ending one sentence in that section in an actual faith tenet:
"...therefore likely to support life. "

Now contrast to the serious barrier so much water would seem to cause to life arising.

https://phys.org/news/2018-03-trappist-exoplanets-life.html#nRlv

See how one is a hopeful, wishful view and the other a more neutral effort to consider?

Expect that. There will often be a mix of some science and a lot of wishing in many articles on this we can expect.

 

[FrumiousBandersnatch]

Look also at this new article for what I call hopeful hand waving (imagination? Or more a sort of faith attitude I think)

Look at the first paragraph under A closer look at the TRAPPIST-1 planets (actually ending in an exclamation point heh heh; they are excited for any planet not desiccated by flares and ordinary solar wind)

https://phys.org/news/2018-04-astronomers-earth-like-planets-capable-hosting.html

...Even ending one sentence in that section in an actual faith tenet:
"...therefore likely to support life. "

Now contrast to the serious barrier so much water would seem to cause to life arising.

https://phys.org/news/2018-03-trappist-exoplanets-life.html#nRlv

See how one is a hopeful, wishful view and the other a more neutral effort to consider?

Expect that. There will often be a mix of some science and a lot of wishing in many articles on this we can expect.

You truncated the quote from the first article:

"This further supports the theory that they may be similar in composition to Earth, and therefore likely to support life."
​

Sounds more reasonable in context.

If they are not similar to Earth, it's a different matter.

 

[Halbhh]

The point: they are not similar to earth, as in the 2nd article. But in the first article, the starry eyes control.

 

[FrumiousBandersnatch]

The point: they are not similar to earth, as in the 2nd article. But in the first article, the starry eyes control.

That's the thing about science - hypotheses and expectations can change dramatically with new observations or analysis.

 

[Halbhh]

That's the thing about science - hypotheses and expectations can change dramatically with new observations or analysis.

Yes, and its so delightful also to have Tess and Webb arriving ( Webb delayed though a couple more years). A lot of people though are going to be surprised or disappointed to learn less romantic things about these planets around these RD stars its looking like.

 

[morse86]

I think the topic title is mispelled. It should be called Astrology News.

All of the satellite telemetric data can be easily coming from a super computer. The $cientists that read the telemetric data think it's coming from a satellite.