Questions tagged [color-index]

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Star cluster absolute magnitude and color index

I'm given a question where I need to calculate the absolute magnitude (Mv) and color index (B-V) of a star cluster consisting of 40 Vega type stars and 4000 stars, which have an Mv of +5 and B-V of 1. ...
user49070's user avatar
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Why is the colour-index measurement used?

So I'm learning about the colour-index currently and what is confusing me is why this is useful. The colour of a star is dependent on the temperature, so wouldn't astronomers have a natural idea of ...
Jackson's user avatar
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Straightforward conversion from Gaia GDR3 photometry to RGB values

I'm a non-astronomer, but I'm working on a project for which I need to produce CGI renderings of as complete a starfield as I can find. The latest Gaia catalogue release has an impressive 1.5 billion ...
Niall's user avatar
  • 11
2 votes
1 answer

E(B-V) , the color excess between B and V bands, for galaxy at redshift 0

Following Mo et al. 2010 (page 479), the quantity $E(B-V)$, called the color excess between B and V bands, is equal to: $$E(B-V) = A_B - A_V = (B - V) - (B - V)_0 = (m_B - m_V) - (M_B- M_V)$$ where $...
fslack's user avatar
  • 51
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How to determine temperatures for a binary system?

How to make a guess for temperatures of an eclipsing binary from light curves measured in UBVR filters of the Johnson system? I assume that differences of indexes U, B, V will be necessary, right? ...
Elisabeth's user avatar
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What does the Reddening line represents in this U-B vs B-V plot?

The plot is from this paper (pg-8). They have also talked(in the same paper) about how central stars from galactic longitude range $20^\circ-80^\circ$ will have a very unusual Reddening line (pg-9). ...
Vampy's user avatar
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4 votes
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Given that a color index ($B-V$) of star A is lower than that of Star B, What can we say about the stars?

The color index $B-V$ of the star is defined as $$B-V\equiv M_B-M_V$$ Let us suppose it's given $$(B-V)^{(A)}<(B-V)^{(B)}\Rightarrow M_B^A-M_V^A>M^B_B-M^B_V$$ The notations are a bit confusing, ...
Young Kindaichi's user avatar
1 vote
2 answers

Corresponding BV Value to a Hertzsprung–Russell

I have an example BV value from an astronomical catalog of 1.04 (33 Psc, HD Catalog 28). Given only the number 1.04, can that be charted on the HR, or do I need the individual components of the value ...
Jason's user avatar
  • 182