[HN Gopher] A Multiwavelength Look at Proxima Centauri's Flares
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A Multiwavelength Look at Proxima Centauri's Flares
Author : JPLeRouzic
Score : 51 points
Date : 2025-04-03 07:07 UTC (4 days ago)
(HTM) web link (www.centauri-dreams.org)
(TXT) w3m dump (www.centauri-dreams.org)
| lifeisstillgood wrote:
| I sometimes liken our civilisation as a reed mat floating across
| the pacific but with ants on it who have invented telescopes, and
| are trying their best to work out what sales are on at 5th Avenue
| - I love that we are "concerned" about atmospheric stripping
| millions of miles away - it gives me hope for those ants floating
| around
| wil421 wrote:
| What if we are the only ants in the ocean?
| imglorp wrote:
| Isn't that super unlikely?
|
| It seems like there are planets in most star systems. Even
| given what's been called a "gross underestimation" of 10^24
| stars in the (observable) universe, even if you define some
| habitable zone based on our n=1 experience, even if you take
| some away based on the OP paper saying flares might make
| things a little harder at Prox, then that's still many
| Sagans* worth of planets, each of which gets a shot at
| growing telescope builders. That's a lot of chances.
|
| * "billions and billions"
| dylan604 wrote:
| Even if...we'd still be too far away to communicate in any
| meaningful way. If today we were to send a message
| equivalent to a signal flare, it would not be received
| within any of our lifetimes and some within any of our
| species' lifetime.
| Alive-in-2025 wrote:
| That's true. But there's a separate question, why no
| radio frequency evidence of other stars. I want to see
| some estimates of the liklihood of radio freq of some
| kind of communication in just our galaxy. How many stars
| might have earth-distanced planets from a sun - 6 billion
| in just our galaxy! Details below from a paper.
|
| If there were this many, I hope in my lifetime we hear
| from some, just evidence of other intelligent life.
|
| Here's a paper that estimates the presence of these
| planets from the Kepler space observatory.
| https://www.icds.psu.edu/how-many-earth-like-planets-are-
| aro...
|
| From 2019, it says using data from Kepler, they estimate
| that a close to earth sized planet (3/4 to 1.5 size of
| the earth) was in an orbit that could potentially have
| water vapor from a sun, orbital periods 327 to 500 days,
| with fairly large error bars:
|
| * somewhere in the range of 1 of every 33 stars to as
| high as one such planet for every 1 out of 2 stars in our
| galaxy.
|
| That's a large range, but given we have at least 200
| billion stars in just our own Galaxy, that lower bound is
| about 6 billion stars with somewhat close to earth-
| distance planets, in just our galaxy. If this is over
| estimating by a million times, that's still 6 million
| planets in the earth like orbiting range. So let's make
| some noise, aliens.
|
| This source says estimates are 200 to 400 billion stars
| in the milky way. https://bigthink.com/starts-with-a-
| bang/how-many-stars-milky...
| dylan604 wrote:
| The universe is ~14 billion years old. We didn't come
| along until a few million years ago, and then it took
| just until a hundred to two hundred years ago to be able
| to actually broadcast our existence. So if some other
| civilization had a similar timeline but much earlier,
| their signal could have come and gone by the time we
| could detect it. Their star could have also already
| reached the point where it destroyed its planet the
| civilization was located, so we'd never know about them.
| It's the same fate our planet has in store for it as
| well. If there's any civilization that comes after
| Earth's demise, they'd never know we were here either.
| Alive-in-2025 wrote:
| Agree that other people could well have vanished by the
| time we randomly wander into their signals. The same is
| true for our radio.
|
| But I'm trying to focus on something else, the existence
| of other intelligent life is the key thing I hope to see.
| And we could destroy ourselves this afternoon of course.
|
| I don't care as much about do they exist still - that's
| icing on the cake. It's the idea that we aren't alone,
| that's the key to me. I'm certain there have been other
| intelligent civilizations in the universe because of the
| size, etc. We need evidence to know for sure.
| leptoniscool wrote:
| > _why no radio frequency evidence of other stars_
|
| unless the radio beam is aimed directly at us, we may not
| be able to detect the radio communication of other
| civilizations.
| pfdietz wrote:
| > Isn't that super unlikely?
|
| We don't know enough to say whether it is unlikely or not.
| Pointing to lots of stars and waving your hands doesn't
| represent an argument.
| indoordin0saur wrote:
| Been reading this gem of a blog for years. Happy to see it get
| some attention here.
| 0hijinks wrote:
| > Small M-dwarf stars ... operate through convection ... likened
| to what we see in a boiling cauldron of water.
|
| > Larger stars like the Sun show a mix of radiative transfer -
| photons being absorbed and reabsorbed as they make their way to
| the surface - and convection.
|
| > That enhances M-dwarf flare activity as their plasma is twisted
| and rotated, producing magnetic fields that snap open only to
| reconnect.
|
| This is the first post I've seen targeted toward generic geeks
| that explained it that way. It makes total sense, is really cool,
| and I'm glad they wrote this article.
| pfdietz wrote:
| M dwarf stars, being fully convective (at least, the ones
| lighter than 0.35 Msun), cycle their entire material content
| through their cores. This is unlike the Sun, where the core is
| effectively isolated from overlying layers, and will run out of
| hydrogen while those outer layers still contain a great deal of
| it.
|
| As a result, and due to their low luminosity, M dwarf stars can
| go on burning hydrogen for a very long time, perhaps as long as
| 12 trillion years for a 0.1 Msun star, much longer than the
| universe has existed so far.
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