View Single Post
  #6  
Old 11-03-2009, 04:59 PM
ngcles's Avatar
ngcles
The Observologist

ngcles is offline
 
Join Date: Dec 2006
Location: Billimari, NSW Central West
Posts: 1,664
R Doradus ??

Hi PGC & All,

Quote:
Originally Posted by pgc hunter View Post
R Doradus, mag 5.5
Nice and bright, deep orange in colour.

...

V hydra, mag 6.8
Now this is an impressive sight! Very deep orange, bordering on actual red I'd say, it is certainly redder than X Tra and comes close to DY Crucis, but is 2 magnitudes brighter and there is no bright star nearby to overpower it.
Actually just on this I'm pretty sure (please corect me if wrong) but I don't think R Dor is a Carbon star either. It is a very cool and late spectral type Mira star but not a Carbon star. The Spectra is M8 III -- 'bout as cool as you can get in "normal" stars.

R Dor is as a matter of interest one of the brightest things in the sky in the near infra-red. If our eyes could see in either K or J band (1.25 and 2.2 mircometres respectively) R Dor would outshine nearly everything else. In these two bands it would be either the third or second brightest star in the sky at a whopping magnitude -2.6 (Jupiter's brightness) in J-band or in K-band mag -4.2 = Only a little dimmer than Venus.

Check out this table:

http://spider.ipac.caltech.edu/staff.../davystars.txt

To see the brightest stars in the sky in visual light, J and K-band. Very interesting indeed.

Of this list V Hydrae is probably the "best" -- as you have found. Except for Kapteyn's star (discussed previously) all are Mira or pseudo-Mira, or semi-regular type long-period variable stars.

So, you've taken the time to find these, why not then become a variable star observer while you're at it?


Best,

Les D

Last edited by ngcles; 11-03-2009 at 05:24 PM.
Reply With Quote