Reddenings, Metallicities, and Possible Abundance Anomalies in Young Globular Clusters

Details Reddenings, Metallicities, and Possible Abundance Anomalies in Young Globular Clusters Reddenings, Metallicities, and Possible Abundance Anomalies in Young Globular Clusters

Jan 1997

adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=1997aj....113..264s&link_type=abstract

Astronomical Journal v.113, p. 264-278 (1997)

Other

58

Scientific paper

We present new photometry in the VI passbands for the ``young'' globular clusters Rup 106, Ter 7, and Arp 2. After formulating the simultaneous reddening and metallicity (SRM) method of Sarajedini (1994) in the BV passbands, we apply it, along with the SRM method in VI, to the red giant branches (RGBs) of these clusters using B-V photometry from the literature and the V-I data presented herein. We find [Fe/H] = -1.90 +/- 0.10, E(B-V) = 0.18 +/- 0.02 for Rup 106, [Fe/H] = -0.82 +/- 0.15, E(B-V) = 0.07 +/- 0.03 for Ter 7, and [Fe/H] = -1.84 +/- 0.09, E(B-V) = 0.10 +/- 0.02 for Arp 2. Furthermore, in light of this new abundance for Ter 7 and recent work on the luminosity of the red horizontal branch, we rederive the age of Ter 7 finding it to be some 6 Gyr younger than 47 Tuc. We show that the SRM method is insensitive to age for clusters with purely red HBs and ages as young as ~ 5 Gyr; for clusters with bluer HBs, the SRM method is only mildly sensitive to age differences between such clusters and the calibrating (standard) clusters. From these metallicity estimates, we conclude that the photometric abundances of the program clusters based on the properties of the RGB are systematically lower (Delta [Fe/H] = 0.1-0.4 dex) than those derived using other indicators, in particular the Ca 2 triplet method. We note that the young globular clusters Pal 12 and possibly IC 4499 also exhibit this behavior. We suggest that this discrepancy is due to systematic differences in the [alpha /Fe] ratios between the young clusters and the ``normal'' Galactic globulars used to calibrate the abundance determination methods. However, we are unable to completely reconcile all the observations of Rup 106 using this approach. Systematic differences in [alpha /Fe] between the young clusters and the rest of the Galactic globulars may indicate differences in their chemical enrichment histories, perhaps due to differing environments at the times of their formation. Interestingly, both Ter 7 and Arp 2 are believed to be memebers of the Sagittarius dwarf galaxy, while Rup 106 and (perhaps) Pal 12 are suspected of being captured from the Magellanic Clouds.

Affiliated with

Also associated with

No associations

Rating

Reddenings, Metallicities, and Possible Abundance Anomalies in Young Globular Clusters 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 Reddenings, Metallicities, and Possible Abundance Anomalies in Young Globular Clusters, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Reddenings, Metallicities, and Possible Abundance Anomalies in Young Globular Clusters will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-1784821