Astronomy and Astrophysics – Astrophysics
Scientific paper
1998-10-16
Astronomy and Astrophysics
Astrophysics
38 pages text, 20 figures, accepted for ApJ
Scientific paper
10.1086/307268
We present new VI photometry for the halo globular cluster M30 (NGC 7099), and compute luminosity functions (LFs) in both bands for samples of about 15,000 hydrogen-burning stars from near the tip of the red giant branch (RGB) to over four magnitudes below the main-sequence (MS) turnoff. We confirm previously observed features of the LF that are at odds with canonical theoretical predictions: an excess of stars on subgiant branch (SGB) approximately 0.4 mag above the turnoff and an excess number of RGB stars relative to MS stars. Based on subdwarfs with Hipparcos-measured parallaxes, we compute apparent distance moduli of (m-M)_{V} = 14.87+/-0.12 and 14.65+/-0.12 for reddenings of E(V-I)=0.06 and 0.02 respectively. The implied luminosity for the horizontal branch (HB) at these distances is M_V(HB)=0.11 and 0.37 mag. The two helium indicators we have been able to measure (R and Delta) both indicate that M30's helium content is high relative to other clusters of similar metallicity. M30 has a larger value for the parameter Delta V_{TO}^{HB} than any of the other similarly metal-poor clusters for which this quantity can be reliably measured. This suggests that M30 has either a larger age or higher helium content than all of the other metal-poor clusters examined. The color-difference method for measuring relative ages indicates that M30 is coeval with the metal-poor clusters M68 and M92.
Bolte Michael
de Oliveira Mendes Cl.
Hesser James Edward
Langer Edward G.
Sandquist Eric L.
No associations
LandOfFree
Wide-Field CCD Photometry of the Globular Cluster M30 does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with Wide-Field CCD Photometry of the Globular Cluster M30, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Wide-Field CCD Photometry of the Globular Cluster M30 will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-587337