Questions tagged [absolute-magnitude]

Use this tag for questions that are about the brightness of a celestial object as seen from 10 parsecs away.

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Gaia Gbp - Grp: why does it get larger as star gets redder?

As an enthusiastic amateur scientist, I'm plowing my way through a cool Gaia DR2-based paper, "An Empirical Measurement of the Initial-Final Mass Relation with Gaia White Dwarfs". I'm doing all right, ...
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When calculating absolute magnitudes of distant objects, do you use the light-travel distance or the comoving distance?

I want to calculate the absolute magnitude of GN-z11. Its light-travel distance is 13.4 billion ly (4.1 Gpc), its comoving distance is 32 billion ly (9.8 Gpc), and its apparent magnitude is $25.8$. ...
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Conversion of UBVRIJHK magnitudes to luminosity?

So, I know that the standard for conversion from bolometric magnitude to luminosity established in 2015 equates to: L = 10^(-0.4 * magnitude) * 3.0128e28 Easy ...
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What spectral type of star has an absolute magnitude of exactly 0?

We know that Vega is the star that serves as the zero point for the UBV color scale, and has an apparent magnitude of nearly zero (+0.02). But its absolute magnitude is +0.58, making it rather far ...
1 vote
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Calculate the absolute magnitude for a multi-star system

We know that the absolute magnitude of a single star can be calculated with the formulae: $$M_{\rm bol} = 4.75 -2.5 \log_{10} \left(\frac{L_*}{L_{\odot}}\right)\ ,$$ $$M = -2.5 \log_{10}(L_* / L_0),$$...
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Is there a formula for absolute magnitude that does not contain an apparent magnitude term?

I have a star that I need to calculate the absolute magnitude of. I am given the temperature, luminosity, radius, mass, and distance in light-years. So I am wondering, what is the formula to compute ...
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Apparent magnitude of a spherical body with specular, rather than diffuse reflectivity? How bright were Sputnik 1 and Vanguard 2?

How bright are geostationary satellites due to reflected sunlight? and Did Sputnik 1 tell us more than “beep”? What science was improved by information gained from its orbiting the Earth? now have me ...
1 vote
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Which star has the lowest absolute magnitude?

I have seen many lists of stars with the most luminosity, mass, and temperature, but I have never seen one that is about absolute magnitude. So I'm wondering, which star has the lowest absolute ...
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Distance and absolute brightness

This is an exercise from a text, I’m learning from and I can’t understand it so I’m asking just to develop my knowledge: The explosion of V603 Aql (Nova Aquilae) took place in June 1918. The nova ...
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Best way to simulate star sizes to scale in celestial sphere

Using the Hipparcos catalogue, I am trying to create a celestial sphere. As all the stars are a fixed distance from the centre of this sphere, the only way to differentiate the distances and magnitude ...
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Calculating star radius from temperature and absolute magnitude - what am I missing?

In an attempt to visualise nearby stars, I've tried to get the star radius (measured in solar radii) using the equation provided on the following site: http://cas.sdss.org/dr4/en/proj/advanced/hr/...
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Is there a relationship between stars' absolute magnitude, spectral class and relative location in a cluster?

I am interested to know whether a pattern has been observed with regard to the characteristics of a star (in particular, its absolute magnitude and spectral class) and its location relative to others ...
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Distance to star using color index

I'm doing the following question: A star is observed with UBV magnitudes $m_u = 16.31$, $m_b = 14.52$, $m_v = 13.76$. Spectral analysis gives $M_{bol} = 7.31$, $BC = -1.02$, $(U − B)_0 = 1.222$. ...
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How to convert luminosity at rest frame wavelength of 1450 A to absolute magnitude at 1450 A?

How do I convert the luminosity (erg sec$^{-1}$ Hz$^{-1}$) of a quasar at a rest frame wavelength of 1450 Angstroms to absolute magnitude at the same wavelength? I know that the bolometric ...
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Rendering stars in 3D space - AbsMag to OpenGL scale values

I am using the AMNH's Digital Universe stars.speck file to render stars in 3D space. The speck contains parsec-scale coortinates, where our Sun is at 0,0,0. It also lists the AbsMag values - i.e the ...
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How to interpret error of absolute magnitude of a star given data from wikipedia?

This Wikipedia page contains information about the star Spica in the rightmost table. A small snapshot of this table is below. In this table, the absolute magnitude is given as ...
164 views

Snowball Earth brightness

The Earth likely froze over almost completely about 700 million years ago. This increased its albedo significantly, and I wonder if that would have a considerable effect on its apparent magnitude from ...
1 vote
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Relationship between Hubble paramater and absolute magnitude

I have a set of data that is absolute magnitude of a star and its redshift. Is there any way to compute the value of the hubble parameter given that magnitude and redshift?
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Is albedo ever greater than unity? How is it calculated for various surface diffusivities and specular reflection? [duplicate]

I'm trying to understand how albedo would be calculated for a body with well-characterized surface reflectance properties, so that it's absolute magnitude could be defined. One could argue that this ...
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Table of absolute magnitudes of stars by spectral type and photometric band

I would like to find a table where I can, say, look for K5 dwarfs and read off that stars of that type have on average an absolute magnitude of X.XX in the infrared L band and Y.YY in the G band. I've ...
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Absolute magnitudes with dust extinction

I have a distant $z\sim3$ galaxy with absolute AB magnitudes $M_B$ and $M_I$, where the central wavelengths of the $B$ and $I$ passbands are $\sim0.4\,\mu\text{m}$ and $\sim0.8\,\mu\text{m}$, ...
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In the JPL small body browser, why is uncertainty on absolute magnitude "N/A"?

In the JPL small body browser, orbital elements are all provided with uncertainties and even a covariance matrix, such as for 2013 LA2. Very good. But underneath, the absolute magnitude is reported ...
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Is there an acceptable value for the absolute magnitude of horizontal branch stars?

I'm writing a test for a gen-ed level astronomy class that I teach, and would just like a good reliable number to use as the basis for a distance calculation question. And yes, I know that real ...
1 vote
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Mass-magnitude relation of evolved stars

In short: what mass is appropriate for absolute magnitude $M_V \sim -7$? Some context: I'm processing the observational data (supernova light curve) and curve fitting gives me about $0.4M_\bigodot$ ...
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How to calculate luminosity in g-band from absolute AB magnitude and luminosity distance?

How can I calculate the (non-bolometric) luminosity $L$ of a galaxy (or a star for that matter) over a given band from its AB apparent magnitude $m_{AB}$ over that band and its luminosity distance \$...
1 vote
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How to find a Cepheid's pulsation period using its graph?

Basically, I've been seeing these graphs that say: Cepheid Period-Luminosity Relation and the Period axis is supposed to be "logarithmic"; How does this graph work? Since the luminosity of a star ...