Definition of spectral types

General physics and astronomy discussions not directly related to Celestia
Topic author
ajtribick
Posts: 1780
Joined: 11.08.2003
With us: 15 years 3 months
Location: Switzerland

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?

Avatar
selden
Posts: 9997
Joined: 04.09.2002
With us: 16 years 2 months
Location: NY, USA

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 :-)
Selden

Ynjevi
Posts: 132
Joined: 13.01.2003
With us: 15 years 10 months

Post #3by Ynjevi » 03.03.2006, 07:55

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


Really?

Avatar
selden
Posts: 9997
Joined: 04.09.2002
With us: 16 years 2 months
Location: NY, USA

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. :(
Selden

d.m.falk
Posts: 105
Joined: 03.07.2005
With us: 13 years 4 months
Location: Eureka, California

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.

Avatar
selden
Posts: 9997
Joined: 04.09.2002
With us: 16 years 2 months
Location: NY, USA

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.
Selden

MKruer
Posts: 501
Joined: 18.09.2002
With us: 16 years 2 months

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 ...

Avatar
Joey P. M
Posts: 82
Joined: 28.10.2017
Age: 16
With us: 1 year
Location: Vladivostok, Russia

Post #9by Joey P. » 04.11.2018, 19:08

Joey P.


Return to “Physics and Astronomy”

Who is online

Users browsing this forum: 7 guests