<p>I am thinking about the Bright Star Catalogue and how it is not a good representation of a typical population of stars. The Bright Star Catalogue includes all the visible stars from Earth when viewing with the naked eye. Therefore, it only includes higher mass stars at various stages of evolution since these are more easily seen; however, most stars in any stellar population will be of lower mass. Lower mass stars are much more plentiful in comparison (see initial mass function/IMF for details). The Bright Star catalogue is limited to stars ~6.5 apparent magnitudes and brighter (so lower numbers since magnitudes run in the &quot;opposite sense&quot;. ie. brighter = a lower number). The question is, which star is at the seeing eye limit (~6.5 - 7 apparent magnitudes), yet has the lowest absolute magnitude? Another way of phrasing this question is, what is the lowest mass star we can see from our Earth with the naked eye? I am not looking to receive an answer about how the answer depends on absolute magnitude and distance (ie. the distance modulus). I understand that already. I am curious what the star actually is (ie. name etc).</p>
<p>Edit to add for clarity:</p>
<p>Luminosity does not increase monotonically with mass. For the sake of this question, let's stick with the faintest absolute magnitude main-sequence star.</p>

CC BY-SA 4.0
2021-08-02T16:47:08.780Z
Not sure that there is a definitive answer - as the limiting magnitude depends on both, you geographic location, the weather conditions and especially the quality of your eye sight. So if you define the magnitude you can still see, it's a simple star catalogue query.
planetmaker
CC BY-SA 4.0
2021-08-02T16:49:25.337Z
I'm looking for an answer that does not depend on fine details such as seeing and geography. Assuming typical conditions, what is the lowest mass star anyone in any hemisphere would likely see from Earth? Let's say 7 magnitudes and above.
Astroturf
CC BY-SA 4.0
2021-08-02T17:24:00.207Z
Surprisingly more difficult as sinbad does not have stellar masses. Assuming main sequence and the later the spectral type, the lower the mass, this query will give you a list of K-type stars with a magnitude brighter than 6. I'd focus on the two K5V stars and see which is lowest mass.
planetmaker
CC BY-SA 4.0
2021-08-02T17:24:03.790Z
http://simbad.u-strasbg.fr/simbad/sim-sam?Criteria=Vmag+%3C+6+%26+sptypes+in+%28%27M0%27%2C%27M1%27%2C%27M2%27%2C%27M3%27%2C%27M4%27%2C%27M5%27%2C%27M6%27%2C%27M7%27%2C%27M8%27%2C%27M9%27%2C%27L0%27%2C%27L1%27%2C%27L2%27%2C%27K9%27%2C%27K8%27%2C%27K7%27%2C%27K6%27%2C%27K5%27%2C%27K4%27%2C%27K3%27%2C%27K2%27%2C%27K1%27%29+%26+splum+%3D+%27V%27%0D%0A%0D%0A&submit=submit+query&OutputMode=LIST&maxObject=10000&CriteriaFile=
planetmaker
CC BY-SA 4.0
2021-08-02T18:55:16.503Z
I'm making the assumption that the lowest mass star we could see is still on the main sequence. Under this assumption, the dimmest absolute magnitude star will generally be the least massive.
Astroturf
CC BY-SA 4.0
2021-08-02T18:58:41.663Z
I could be wrong in that assumption, but for arguments sake, I think it would be the most interesting since most stars spend the majority of their lives there, particularly the lowest mass ones.
Astroturf
CC BY-SA 4.0
2021-08-02T19:10:02.493Z
That's true. I didn't think of that at the time of asking the question. I was more looking for a "ballpark answer" out of curiosity but of course things can get much more technical so sticking to main sequence stars at the lowest luminosity end would make the most sense. Thanks!
Astroturf
CC BY-SA 4.0
2021-08-02T19:44:28.873Z
61 Cygni must be in the running...
James K
<star><observational-astronomy><amateur-observing><hr-diagram>
Which star has the faintest absolute magnitude (largest magnitude) yet is still visible with the naked eye from Earth (either hemisphere)?
Astroturf
# Which star has the faintest absolute magnitude (largest magnitude) yet is still visible with the naked eye from Earth (either hemisphere)?

(Asked by: username_0 on 2021-08-02)

I am thinking about the Bright Star Catalogue and how it is not a good representation of a typical population of stars. The Bright Star Catalogue includes all the visible stars from Earth when viewing with the naked eye. Therefore, it only includes higher mass stars at various stages of evolution since these are more easily seen; however, most stars in any stellar population will be of lower mass. Lower mass stars are much more plentiful in comparison (see initial mass function/IMF for details). The Bright Star catalogue is limited to stars ~6.5 apparent magnitudes and brighter (so lower numbers since magnitudes run in the "opposite sense". ie. brighter = a lower number). The question is, which star is at the seeing eye limit (~6.5 - 7 apparent magnitudes), yet has the lowest absolute magnitude? Another way of phrasing this question is, what is the lowest mass star we can see from our Earth with the naked eye? I am not looking to receive an answer about how the answer depends on absolute magnitude and distance (ie. the distance modulus). I understand that already. I am curious what the star actually is (ie. name etc).

Edit to add for clarity:

Luminosity does not increase monotonically with mass. For the sake of this question, let's stick with the faintest absolute magnitude main-sequence star.

**Tags:** star, observational-astronomy, amateur-observing, hr-diagram
> **Comments:**
> **username_1**: Not sure that there is a definitive answer - as the limiting magnitude depends on both, you geographic location, the weather conditions and especially the quality of your eye sight. So if you define the magnitude you can still see, it's a simple star catalogue query.  
> **username_0**: I'm looking for an answer that does not depend on fine details such as seeing and geography. Assuming typical conditions, what is the lowest mass star anyone in any hemisphere would likely see from Earth? Let's say 7 magnitudes and above.  
> **username_1**: Surprisingly more difficult as sinbad does not have stellar masses. Assuming main sequence and the later the spectral type, the lower the mass, this query will give you a list of K-type stars with a magnitude brighter than 6. I'd focus on the two K5V stars and see which is lowest mass.  
> **username_1**: http://simbad.u-strasbg.fr/simbad/sim-sam?Criteria=Vmag+%3C+6+%26+sptypes+in+%28%27M0%27%2C%27M1%27%2C%27M2%27%2C%27M3%27%2C%27M4%27%2C%27M5%27%2C%27M6%27%2C%27M7%27%2C%27M8%27%2C%27M9%27%2C%27L0%27%2C%27L1%27%2C%27L2%27%2C%27K9%27%2C%27K8%27%2C%27K7%27%2C%27K6%27%2C%27K5%27%2C%27K4%27%2C%27K3%27%2C%27K2%27%2C%27K1%27%29+%26+splum+%3D+%27V%27%0D%0A%0D%0A&submit=submit+query&OutputMode=LIST&maxObject=10000&CriteriaFile=  
> **username_0**: I'm making the assumption that the lowest mass star we could see is still on the main sequence. Under this assumption, the dimmest absolute magnitude star will generally be the least massive.  
> **username_0**: I could be wrong in that assumption, but for arguments sake, I think it would be the most interesting since most stars spend the majority of their lives there, particularly the lowest mass ones.  
> **username_0**: That's true. I didn't think of that at the time of asking the question. I was more looking for a "ballpark answer" out of curiosity but of course things can get much more technical so sticking to main sequence stars at the lowest luminosity end would make the most sense. Thanks!  
> **username_2**: 61 Cygni must be in the running...  

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## 0 answers

