Unanswered Questions
227 questions with no upvoted or accepted answers
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What are You misunderstanding about the scale factor-redshift relation?
If the scale factor as a function of time represents or is equal to the average distance between the galaxies, then it increases altogether with the CMB redshift $z$, but it also must be equal to the ...
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0
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39
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Star forming regions
Some star forming regions, like Bok globules (which contain stars that still haven't dispersed their molecular hydrogen and cosmic dust shell) appear dark compared to the rest of the H II in which ...
- 365
1
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0
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46
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What's the density of Proxima Centauri's photosphere?
Proxima Centauri is a red dwarf much denser (33X on average) than the sun. Yet I'm not finding anything about Proxima Centauri's photosphere. The Sun's photosphere is only 0.2 g/m3 (1/10,000th of sea ...
- 123
1
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16
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cross-matched SDSS-WISE catalog
Please where can I find cross-matched SDSS and WISE dataset for a machine learning project?
(Galaxy-star-qso classification task)
2
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0
answers
84
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Would we know if the universe was rotating?
I was wondering what we would observe if the universe had a small rotation. My conclusion was that galaxies on the equatorial plane of the universe would be slightly more redshifted than galaxies than ...
- 373
3
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41
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Why MIT's Benjamin Rackham says "nearby ultracool dwarf SPECULOOS-3" would look "purplish-red, spotted, and flaring" from an airless orbiting planet?
May 15, 2024 MIT News article Newly discovered Earth-sized planet may lack an atmosphere includes the following:
“We can say from our spectra and other observations that the star has a temperature of ...
- 30.7k
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35
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Project Analog Hypothetical Planet
For my story Project Analog, I was wondering if a hypothetical planet (Let's call it Suria). It has the same size and conditions as Earth with the same axis, tilt, and rotation, as well as one moon. ...
CommunityBot
- 1
1
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0
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39
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Comprehensive Stellar Evolution Article
Is there an article that comprehensively covers stellar evolution, from start to finish. I've found articles on this, one in an introduction to a stellar evolution model, and I am searching for more. ...
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2
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66
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Single, binary, triple, .. fraction of star systems in our galaxy by mass
What is the fraction of single, binary, triple and so on systems as a function of one of the stars masses (or their sum)?
This can be either derived from simulation or measurement.
I feel like I have ...
- 3,441
2
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0
answers
102
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What would the Big Crunch theoretically look/feel like?
In the Big Crunch theory, the expansion of the universe reverses, resulting in all matter contracting into a single point. Imagine you are alive at the time of this event. What would the sky look like?...
- 29
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21
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What direction do Herbig Haro outflows go from?
After doing some research about Herbig Haro objects, I found that the outflows are formed perpendicular to the circumstellar disk. Is that the same direction as the star's rotation, or is it the ...
- 825
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0
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48
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What do you call a protostar with more than 10 solar masses?
PMS Stars with less than 3 solar masses are T Tauri stars, and PMS stars between 3 and 10 solar masses are herbig ae/be stars, so what do you call a star with more than 10 solar masses? Is there ...
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1
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40
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Hayashi Track vs Red Giant branch
Are the red Giant branch and the Hayashi track the same thing? After doing some research, I found some similarities between the two, such as both aree fully convective. However, the T Tauri phase does ...
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2
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0
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34
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Local anisotropies in the expansion of the universe and tidal forces...?
In the context of the large-scale structure of the universe, there can be local anisotropies (https://www.aanda.org/articles/aa/full_html/2021/05/aa40296-21/aa40296-21.html).
I understand from this ...
- 1,017
4
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0
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194
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'Star' appeared dimmer and dimmer over multiple days before disappearing. What could this have been?
This happened a little while ago but I've just been thinking about it!
I was in Wales for a holiday, and over the period of 7 days, a particularly bright 'star'(or at least a bright dot that looked ...
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