Questions tagged [red-dwarf]
Questions about red dwarfs, the smallest and most abundant stars in the universe.
50 questions
0
votes
0
answers
24
views
Is GJ 3470 a flare star variable type?
Is GJ 3470 (also known as Kaewkosin) a flare star variable type? I have wondered if it was a flare star variable type because it is an M-type star, and it could be possibly a young one.
- 115
9
votes
2
answers
891
views
Red dwarfs and red giants
I have a quick question. I have heard that red dwarfs that are approximately less than 0.35-0.5 solar masses are fully convective, meaning that they do not become red giants. I have also heard that ...
- 115
12
votes
1
answer
1k
views
Are any Population III stars red dwarfs?
Everything I read about Pop 3 stars says that they were hugely massive stars that died very, very rapidly (relative to stars today), and so it may not be actually possible to find these stars, even ...
- 231
7
votes
2
answers
778
views
Why do red dwarf (M-type) stars give off such violent flares and CMEs, out of proportion to their size and temperature?
Dr. Becky (Smethurst) just posted a new YouTube video mentioning, as I have heard many times, that it might not be possible for life to form on planets around Red Dwarf (M) stars because they would ...
- 5,585
3
votes
0
answers
84
views
Could double planets in red dwarfs water-habitable zones be stable?
Red dwarfs are so dim that planets in the water habitable zone end up tidally locked to their star. Locking may good for habitability: among other advantages, no axial tilt means less swings of ...
- 930
2
votes
1
answer
253
views
Is life (as we know it) even possible around M-class stars?
My Question is about the fascination in looking for life on M class or Red Dwarf stars.
We all know that Most stars (70%) are M Class, so looking at those stars is going to be important. The "...
- 29
3
votes
1
answer
184
views
Do red dwarf stars get dimmer over time, the opposite of most other main sequence stars?
It is common knowledge, for instance, that the sun has increased in brightness by roughly 40% since its formation... (The apparently early appearance of life has led to the 'Faint young Sun paradox', ...
- 5,585
0
votes
1
answer
66
views
What is a dM1e red dwarf star? What do the '1' and 'e', specifically, stand for?
The Castor-and-Pollux Gemini Dioscuri system contains several red dwarfs classified as type 'dM1e' stars.
I believe the d is dwarf, the M is M-type (redundantly designating a red dwarf?).
What do the '...
- 5,585
2
votes
1
answer
183
views
Why are the largest stars, such as O-type or B-type, most likely to be in multi-star systems; while red dwarfs are least likely?
I was just reading about what percentage of stars in our galaxy and, perhaps, other galaxies are in binary systems (or trinary... etc.).
Researchers keep going back and forth about whether or not most ...
- 5,585
2
votes
0
answers
47
views
How much of the hydrogen in our sun will never participate in fusion? What about larger stars? [duplicate]
From what I gather, only red dwarf stars are fully convective, and will use up pretty much all of their hydrogen....
Is there a chart or list somewhere that shows the percentage of hydrogen that is ...
- 5,585
15
votes
3
answers
3k
views
Is there more dark matter than we previously thought?
With the recent Nature publication showing that M dwarfs did not form in prior epochs as frequently as we had thought, what implications does this have on galaxy mass estimates and, by extension, the ...
- 3,404
2
votes
1
answer
457
views
Lifespan of higher mass red dwarf stars
Wikipedia and the reference paper they are using offer some insights into the lifespan of smaller red dwarf stars (link). However it offers no insight as to what the projected lifespan of larger red ...
- 121
8
votes
1
answer
932
views
Is Barnard's star an M4 red dwarf or an M0? Why is it called an M4.0V?
I have tried to figure this out, but cannot find an answer anywhere...
Are, perhaps, astronomers unsure of its exact spectral class? (I have heard that red dwarfs are usually variable... to an extent....
- 5,585
1
vote
1
answer
207
views
Which star has a higher effective temperature, a red dwarf or a red giant?
According to the Hertzsprung-Russell diagram, they would roughly have the same temperature, but I've read in bibliography that the surface temperature of the red giant is about 5000K
and the one of ...
- 147
2
votes
0
answers
98
views
"Opacity" in red dwarfs
One day, while researching on blue dwarfs in Wikipedia, I stumbled across something that I cannot understand:
Rather than expanding, however, red dwarfs with less than 0.25 solar
masses are predicted ...
- 2,716
6
votes
1
answer
319
views
How would you calculate the "day" on a planet orbiting a red dwarf that is a companion to a larger star?
So the idea is you have an Earth-sized planet with a moon orbiting an M-class star (let's give it .25 solar masses) at 0.2 AU, with an orbital period of 63 days and a 24-hour day. Its orbit has an ...
3
votes
0
answers
77
views
How long would it take for a planet captured by a red dwarf to become tidally-locked if it started out rotating retrograde?
So say for the sake of argument that we have a red dwarf orbiting a G of K-class star. An Earth-sized planet forms, maybe at one of the dwarf star's Lagrange points to its primary, and eventually ...
18
votes
1
answer
3k
views
How can a brown dwarf be more massive than a star?
SDSS J0104+1535 is about 90 times more massive than Jupiter, making it the heaviest known brown dwarf. EBLM J0555-57Ab has a mass of about 85.2±4 Jupiter masses, or 0.081 Solar masses.
I am confused. ...
- 183
3
votes
0
answers
57
views
Would tidally locked Earth-like exoplanets necessarily have hot pole/cold pole atmospheric circulation?
A tidally locked planet orbiting a red dwarf star in its habitable zone would have a rotational period equal to its orbital period, on the order of days or weeks.
Given a thick enough atmosphere ...
- 183
4
votes
1
answer
76
views
At what point does an astronomical body's surface stop being gas giant-like and start being sun-like?
I've generally seen brown dwarfs depicted as more massive and slightly wider Jupiters in varying colors with banded cloud structures, sometimes hot enough to be visible glowing. I've also seen red ...
13
votes
3
answers
2k
views
Are Brown and Sub-Brown Dwarfs secretly more common than stars?
I recently heard that Red Dwarfs are the most common type of star, and low-mass Red Dwarfs are the most common type of Red Dwarf. This seems to imply a generic trend that the lower the mass, the more ...
- 624
0
votes
2
answers
981
views
What factors influence a star's temperature and density?
Assuming a relatively even proportion of mass and radius, a 0.25 solar mass and radius star would have a density of 22.5003 g/cm³, or about 16 times our Sun's density.
However, there is obviously a ...
- 403
6
votes
2
answers
2k
views
Are red dwarfs really 30-100 times our Sun's density?
This article by K. E. Edgeworth claims red dwarfs tend to be around 30-100 times our Sun's density. However, this seems a bit high.
With smaller stars, mass tends to be proportional to radius but ...
- 403
3
votes
1
answer
94
views
Would the electron cyclotron-maser emission mechanism affect Proxima b's ability to retain an atmosphere?
In a recent arXiv preprint, Pérez-Torres et al. "Monitoring the radio emission of Proxima Centauri" claim the detection of radio emissions synchronised with the orbit of the planet Proxima b....
user24157
5
votes
1
answer
745
views
How do we know that 2MASS J0523-1403 is a red dwarf?
I was reading about red dwarfs, and stumbled upon this article about the least massive red dwarf, and noticed several peculiarities:
The spectral type is L2.5
The luminosity class is V
The mass is 67....
- 6,733
0
votes
1
answer
591
views
If the Earth circled a red dwarf/giant or a brown dwarf, would its sky still look blue? [duplicate]
I have the impression that in brown dwarf and weak red dwarf systems, everything looks more reddish on a planet, including its atmosphere regardless of composition. Suppose there's a planet having an ...
- 303
3
votes
1
answer
112
views
Why is the SETI survey limited to only Red Dwarf Stars?
I was going through the official SETI website, when I came across this article on the same website which said :
Today, the SETI Institute uses a specially designed instrument for its SETI efforts – ...
11
votes
1
answer
2k
views
If Sunlike stars become a red giant and eventually a white dwarf, what do red dwarfs become?
The Sun is said to become a red giant at the end of its life (before that it will become an orange subgiant first and then an orange giant or so) and after ejecting its outer layers it should become a ...
- 227
5
votes
1
answer
831
views
Would a red dwarf star resemble our own Sun at sunset to an observer on a nearby planet?
Suppose you're observing a red dwarf star at Noon from the surface of an Earth-like planet orbiting in the red dwarf's habitable zone, so that the red dwarf's luminosity is equal to our own Sun.
Aside ...
- 183
0
votes
1
answer
104
views
Comparing orbits between a planet and Red Dwarf
I have a MATLAB problem, so I have an earth like planet orbiting around a sun like star and then there is a red dwarf on an elliptical orbit around the star that passes close to the planet. I want to ...
- 1
9
votes
1
answer
867
views
Why do planets in red dwarf star systems tend to have a higher probability to get tidally locked?
I have read about about the habitability of red dwarf systems on Wikipedia, as well as some web articles on similar topics. The problem is, it does not explain why and how it happened. Google search ...
- 201
2
votes
1
answer
464
views
At what distance does Proxima Centauri become visible to the naked eye?
The red dwarf star Proxima Centauri is the closest-known star to the Sun (being about 4.2 ly or 1.3 pc away), however it's not visible to the unaided eye for it is too small and dim. I'd like to know ...
- 1,262
10
votes
1
answer
883
views
The colour of blue dwarf stars
The paper "M dwarfs: planet formation and long term evolution" describes blue dwarf stars, a hypothetical next-stage in the lifespan of red dwarf stars within a certain mass range, after which they ...
- 495
0
votes
1
answer
127
views
Are red dwarfs (M dwarfs) known to be strong infrared sources?
If so, why? Are they known to be surrounded by large amounts of dust? Do they typically flare?
user28693
12
votes
3
answers
746
views
Existence of planets larger than their host star?
The mass region of objects between ~ 0.5 Jupiter masses and 80 Jupiter masses (gas giants through to brown dwarfs and red dwarfs) is typified by an almost flat relationship with object diameter. There ...
- 4,185
3
votes
0
answers
112
views
Is it possible for any of the planets in the TRAPPIST-1 system to have moons?
All of the planets in the TRAPPIST-1 system are all orbiting very closely and are somewhat large. Would it be possible for at least one of the planets to have a stable moon in orbit around it? Or ...
- 849
2
votes
1
answer
84
views
How would tidal effects behave in this setup: An icy moon orbiting a gas giant, as the gas giant orbits a red dwarf? [closed]
Let me know if this is more appropriate for worldbuilding.
Essentially, I'd like to know how tidal effects would behave in these circumstances (if it's even stable):
An icy moon orbiting a gas ...
- 123
2
votes
0
answers
104
views
Does habitable zone take tidally locked bodies into account?
Imagine a tidally locked planet orbiting a red dwarf, where habitability is not situated close to terminator zone, but on a "small" cap normal to incident starlight (zenith) with permanent average +15 ...
user16500
2
votes
2
answers
237
views
Will all of the gas in the universe be converted into red dwarf stars?
Red dwarfs have lifespans of trillions of years and are also the most abundant stars, making up 70% of the stars in the Milky Way. No red dwarf star has ever died and none will die for a very, very ...
- 849
0
votes
1
answer
275
views
Do lower mass stars consume more hydrogen than higher mass stars?
If I understand correctly, red dwarfs consume all of their hydrogen and will eventually shrink into helium white dwarfs, whereas the higher mass stars will consume a fair amount of their hydrogen fuel,...
- 921
2
votes
0
answers
263
views
Jupiter/Saturn's fate after Sun goes red giant and planetary nebula?
The solar wind contributes a very small amount of matter to the gas giants. As the sun approaches the red giant phase, the solar wind increases significantly. 10% of the sun's mass lost as solar ...
- 474
0
votes
1
answer
152
views
What if a white dwarf is less massive than her partner?
For example: a system with a 0.2 solar mass white dwarf orbiting a 0.25 solar mass red dwarf. Does the red dwarf steals mass from the white dwarf or vice versa.
14
votes
5
answers
2k
views
Is there any way for a planet orbiting a red dwarf in the habitable zone to not be tidally locked?
Is there any way to avoid the tidal locking of a planet orbiting a red dwarf in the habitable zone?
For example, could a planet with a 90° obliquity and large moon avoid such a situation?
- 243
2
votes
2
answers
899
views
How do I understand a brown dwarf with a M-type spectrum?
There are a large fraction of M dwarfs which are claimed to be brown dwarfs.
Why do we still use M-type and not create a new stellar type like L, T and Y? The main signature of M is TiO absorption ...
- 3,157
1
vote
0
answers
90
views
Could a moon of a mini-neptune around a red dwarf harbour life?
I am planning a game where on could control evolution on an alien world.
I was thinking red dwarf as per here Habitable Planet around Red Dwarf
To my understanding three questions arise:
Tidal lock
...
- 111
4
votes
1
answer
390
views
Are there any hot jupiters orbiting red dwarfs?
Do we know of any hot jupiters that could be orbiting a red dwarf (or, more probably, orbiting a barycenter between the two)? Is this scenario even physically possible?
3
votes
1
answer
206
views
Red dwarf variation in Luminosity
I recently saw this video. The creator of the video says that one of the reasons for non-existence of life on planets around red dwarfs might be that these stars can increase luminosity roughly by a ...
- 528
3
votes
1
answer
426
views
Is there a way to estimate the age of M dwarf stars?
Wolf 1061 (only 13.8 ly away) was recently found to have three rocky planets one of which is in the habitable zone. It was stated on the english wikipedia site that it has a very stable light curve ...
- 383
7
votes
1
answer
764
views
Is the mechanism of solar flares on red dwarfs and brown dwarfs the same as that on the Sun?
The Sun has solar flares that are caused when there is a magnetic reconnection in the Sun's atmosphere, causing a loop of magnetic field to be ejected at high energy, along with a large number of ...
- 129k
2
votes
1
answer
425
views
The tidal locking problem concerning Earth sized planets in habitable zone around Red Dwarfs
Would twin planets orbiting around each other present a solution to tidal locking of habitable planets in red dwarf systems? It's an awfully easy equation to set up. I'm fibbing; I can't do it. I was ...
- 21