Questions tagged [spectral-type]

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Convert from spectral type to RGB color?

I'm writing a night sky simulator and I want to render stars using the correct color. Is there a formula that converts a two-character code (as seen in the Yale Star Catalog) to a RGB value?
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How do I say the luminosity class aloud?

I have need to say the spectral type of a star for a poster presentation I'm making, which includes the luminosity class. However, I've been unable to determine the standard way of doing so, and ...
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What color would stars have with an apparent magnitude of ~-30? [duplicate]

The light of the Sun is white because our eyes are evolved to work with it as the primary light source. Other stars look white in the night sky because they are too faint to activate the color ...
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What does a + (plus) mean in stellar classification?

I've noticed some stellar classifications might look like this: A0IV+G: (HD 70003) F3IV+F0IV (HD 82434) ...
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Spectral class and luminosity of hydrogen bomb explosions?

Since hydrogen bombs detonating are like tiny little stars, I wonder what luminosity and spectral classification they would get if one were to categorize them like this. E.g. Starfish Prime and the ...
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What happened to NS spectral types after OBAFGKM?

What happened to NS after OBAFGKM? The full mnemonic was "O Be a Fine Girl Kiss Me Now Sweetheart" a few decades ago as I remember. I think it was that way in "The Larousse ...
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2 votes
3 answers
578 views

What is a hard spectral state vs. a soft spectral state?

In X-ray astronomy, the source is considered to be in the hard or soft spectral state. So what is the meaning of the hard spectral state? What are the soft state and hard state in spectroscopy?
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How would the characteristics of a habitable planet change with stars of different spectral types?

The tidal forces a habitable planet experiences increase with decreasing spectral type. So a habitable planet orbiting a smaller, less massive, and cooler star would experience much stronger tidal ...
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5 votes
1 answer
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Does "spectral type" and "stellar classification" refer to the same thing?

Should the tags stellar-classification and spectral-type be merged? has been asked in meta two weeks ago. It requires some careful consideration but so far no response has been forthcoming, so I'm ...
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Why is the Sun less massive than other G2V stars?

The Wikipedia page for G-type main-sequence stars lists the expected mass and temperature for stars of each sub-classification: $$\begin{array}{c|c|c|} & \text{Mass ($M_\odot$) } & \text{...
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Is there a luminosity class for brown dwarfs?

I've been reading about brown dwarfs, and checking their spectral types, and I noticed that they do not have a luminosity class (V, VI, etc). So I am wondering, do brown dwarfs have a luminosity class,...
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What does the "a" at the end of a spectral type mean?

Looking at the chart for spectral type peculiarities (here), I noticed that the letter a was missing from the chart. This seems to be an error, as the star Vega has spectral type A0Va, with the a ...
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4 votes
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Are the sub-spectral types (1,...9) based on temperature or spectral lines?

The spectral type of stars has an OBAFGKM class, along with a number, from 0 to 9. According to Wikipedia, (sample shown below), the lower the number, the hotter and more massive the star, but ...
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4 answers
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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 ...
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10 votes
2 answers
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Is there an O1 or O0 star?

Okay, we've seen the super hot Wolf-Rayet stars, especially WR 102 and 142, and the "slash stars," many of which are early O (O2-4.5/WN). We know the temperatures of these Wolf Rayet stars. ...
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Relation between age and spectral type of star

Does the spectral type of a star change as it ages? Since its temperature changes, I suppose the spectral type should also change, but I'm a bit confused about this. Also, is the spectral type ...
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Determine spectral type of star from its properties

How can I determine spectral type of star, if I know all its another properties? For Example, Rigel A has spectral type B8Ia. Rigel has temperature 12 500 K. ...
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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 ...
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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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Has J been used by itself as a spectral type?

While answering the question "Why have brown dwarf classes been dubbed L, T and Y?" I noticed that in the paper Kirkpatrick et al. (1999) "Dwarfs Cooler than 'M': The Definition of Spectral Type 'L' ...
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22 votes
2 answers
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Do we know a star that is similar to the Sun when it would be a red giant?

In about 5 billion years the Sun is predicted to become a red giant and have more than 200 times its current size, reaching a radius of about 5 AU when largest. I wonder what spectral class the Sun ...
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How are Y-dwarf spectral subtypes defined?

It is often stated that the spectral subtype indicates the relative position between spectral types, e.g. G5 being halfway from the start of spectral type G to the beginning of spectral type F. Given ...
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Spectral Class Breakdown

Where can I get a more detailed breakdown of Spectral Classes. Wikipedia only has it at Letter level rather than sublevel. For example, https://en.wikipedia.org/wiki/Stellar_classification has B ...
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2 votes
1 answer
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Examples of absorption lines for main sequence stars

Where might I find a detailed table or figure containing the absorption lines and their corresponding wavelengths for each type of main sequence star? I'm trying to get the chemical abundance of ...
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-1 votes
1 answer
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Compare this planet to Earth and determined its habitability (can humans live in this environment?) [closed]

I'm given this set of data and I need to describe the habitability. Would this not be habitable since the temperature of the albedo and the equilibrium is similar to Earth's or does the Spectral Type ...
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6 votes
1 answer
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Can Jupiter's nightside be classified as spectral type Y?

As far as I am aware, the latest spectral types that have been assigned are around Y2, for objects like WISE 0855-0714 that have temperatures around 250 K or so. I've also seen several directly-imaged ...
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11 votes
1 answer
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How does a star's rotation affect a star on the main sequence?

I searched and have found that the questions mainly focus on neutron stars, white dwarfs and black holes. This was not what I want. Basically, the bigger the star's mass is, the more intense its ...
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5 votes
0 answers
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Need help understanding stellar spectroscopy data from ESO

The European Southern Observatory webpage has a web page that has tabular spectrogram data from A. J. Pickles, University of Hawaii. There are over 130 .dat files there. Each one represents a ...
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2 answers
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Stellar electromagnetic signatures

By using only the electromagnetic signature of a star, could a star be distinguished with reliable accuracy from any other star? To elaborate a little, say we have a collection of about 200,000 stars. ...
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2 votes
2 answers
495 views

Can someone explain this diagram showing the spectral type distribution of bright stars

Can someone explain this diagram? The text is in Dutch, free translation: "You are given a graph: a histogram of the 10 000 most apparent bright stars. Explain 1, 2 and 3." The fact that the number ...
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1 vote
3 answers
2k views

B-V to U-B colour index

Is there a formula to convert the B-V index to U-B index or are they totally different and separate observations and can't be convert like you can with Fahrenheit->Celsius? (Updated) I know F->C ...
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3 votes
1 answer
170 views

Why is TiO special?

Red spectra of M stars are dominated by TiO(Titanium oxide) bands, which have become the primary means of establishing spectral types.see ApJ Why is TiO special? There should be much more Silicon ...
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Solar Spectral Types and Dwarf Stars

On the following page, http://www.uni.edu/morgans/astro/course/Notes/section2/spectraltemps.html It mentions Main, Giants and SuperGiants. However for Dwarf Stars (e.g. D, Sd) , do I apply Main ...
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