# star atlas with absolute magnitude and spectral type

Is there any star atlas someone recommends?

Then for some kind of star with a definite spectral type, we can know its absolute magnitude.

• There are a number of stellar catalogues each with their own ranges and applications (e.g. nearby stars above a given luminosity threshold). Could you elaborate on what you need the catalogue for? – christopherlovell Mar 3 '14 at 18:57
• I need to know the absolute magnitude for a specified stellar type. Then I can use the color index(or SED) which I get from the observational data to infer the stellar type for my sources. – questionhang Mar 4 '14 at 1:20

The parallax (check according box) and vmag will provide a basis for the calculation of the absolute visual magnitude. The absolute visual magnitude may be lower (star may be absolutely brighter), if the extinction isn't negligible.

1/parallax is a good estimate for the distance. Take this distance as an approximate for the luminosity distance, if you can assume negligible extinction. Now calculate the visual magnitude of the star at 10 parsec distance to get the absolute visual magnitude.

Example: Alp1Cen (HR 5459) has vmag -0.01, and parallax 0.751 arc seconds. Therefore the distance is about 1/0.751 = 1.33 parsec. We get absolute visual magnitude $$M=m-5\cdot (\mbox{log}_{10}D_L - 1)=-0.01-5\cdot (\mbox{log}_{10}1.33 - 1)=4.37.$$

More detailed discussion, and tables can be found in this paper.

This book seems to contain a table with values as of 2009, which is cited here.

• Thanks. It is a good catalog to begin with, but bsc5p is observational data which may be affected by many different factors. We do not know whether an OIII star's 'typical' mag. How to know an OIII star's theoretical absolute magnitude? – questionhang Mar 3 '14 at 14:00
• There is not a name for the table in your link. If it is famous, I can cite it. I know there is a Schmidt-Kaler catalog（1982），but I can not find it on line. – questionhang Mar 4 '14 at 1:17
• @questionhang I've been looking about OIII data, but those are rare; OIII stars are blue giants, with absolute magnitude below -5. This paper contains some data (p.1553): mnras.oxfordjournals.org/content/374/4/1549.full.pdf It's also referencing Schmidt-Kaler, but they say, data differ a bit. – Gerald Mar 4 '14 at 1:33
• Thank you. This kind of thing is what I am looking for. But it seems people did not cite that MNRAS paper much. Maybe I still need the traditional schmidt-kaler catalog. – questionhang Mar 4 '14 at 2:08
• @questionhang This (press.princeton.edu/titles/8963.html) seems to be a bit more up-to-date, but it's not free. I've provided a link to a cite of the relevant table in the answer. – Gerald Mar 4 '14 at 2:13