Definition of spectral types

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ajtribick
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Definition of spectral types

Post #1by ajtribick » 02.03.2006, 11:56

What are the criteria used to determine the spectral type/subtype of a star? E.g. where would you draw the dividing line between, say, F8 and F9?

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selden
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Post #2by selden » 02.03.2006, 13:22

Spectral type is determined by obtaining the star's spectrum and comparing it to the spectra of stars which are defined to of a particular classification. The procedure is not necessarily unambiguous. The spectral classification for our Sun is controversial, for example.


http://www.ulo.ucl.ac.uk/~diploma/labor ... S_star.pdf
seems to give a reasonable summary, including homework :-)
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Ynjevi
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Post #3by Ynjevi » 03.03.2006, 07:55

selden wrote:The spectral classification for our Sun is controversial, for example.


Really?

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selden
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Post #4by selden » 03.03.2006, 10:56

Although it's generally considered to be G2V, I've seen at least one article mentioning that some people disagree. Of course, I can't find it now. :(
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d.m.falk
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Post #5by d.m.falk » 04.03.2006, 20:14

Oh, you mean the "Green Sun" theory?

d.m.f.
There IS such a thing as a stupid question, but it's not the question first asked. It's the question repeated when the answer has already been given. -d.m.f.

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selden
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Post #6by selden » 04.03.2006, 20:35

I don't know about any "green sun" theory. What I read was that some people think the Sun should be classified as G3 or maybe even G4.
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MKruer
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Post #7by MKruer » 07.03.2006, 01:41

And if it was based upon temperature it should be classified as a G1 or G0

Danny Lorraine II

Post #8by Danny Lorraine II » 24.05.2018, 20:15

spectral types are defined like this , from hottest to coldest :

w, o0, o1, o2, o3, o4, o5, o6, o7, o8, o9, b0, b1, ... b9, a0 ... m9, r, n, s, l, t, y ...

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Joey P. M
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Post #9by Joey P. » 04.11.2018, 19:08

Joey P.

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Joey P. M
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Post #10by Joey P. » 21.02.2019, 02:06

In my opinion the main types of stars are O, B, A, F, G, K, M, and N.

The old Draper system had O, B, A, C, D, E, F, G, H, I, K, L, M, N, P (planetary nebulae), and Q (other, now for Neutron Stars and Novae). Imagine if Celestia was based on that.
Last edited by Joey P. on 09.03.2019, 22:43, edited 1 time in total.
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Gurren Lagann
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Post #11by Gurren Lagann » 21.02.2019, 22:59

Sorry, but this article is a nigh-absolute-copy of Wikipedia!


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