A Photometric and radial-velocity study of the open cluster NGC 7789
| dc.contributor.author | Gim, Munhwan | en_US |
| dc.date.accessioned | 2024-08-13T22:54:24Z | |
| dc.date.available | 2024-08-13T22:54:24Z | |
| dc.date.copyright | 1998 | en_US |
| dc.date.issued | 1998 | |
| dc.degree.department | Department of Physics and Astronomy | |
| dc.degree.level | Master of Science M.Sc. | en |
| dc.description.abstract | A (V, V - I)-diagram, reaching V ~ 21 (Mv ~ 9), has been derived for the intermediate-age open cluster NGC 7789 from CCD observations of more than 15,000 stars within ~ 18 arcmin of the cluster center. A prominent clump of core helium-burning stars is evident at V = 13.0 and the upper end of the main sequence shows a fairly pronounced curvature to the red, which indicates significant convective core overshooting. Interestingly, if sufficient overshooting is assumed in order to match the main-sequence data, it is not possible to reproduce the cluster's extended giant branch unless the cluster age is at least 1.6 Gyr (assuming a metallicity in the range -0.2 ~ [Fe/ H] :::; 0.0). This, in turn, requires that the cluster have an apparent distance modulus (m - M)v :::; 12.2. We infer a reddening 0.35 :::; E(V - I) :::; 0.38. A total of 597 radial-velocity observations for 112 giant stars, which have been obtained since 1979 with the radial velocity spectrometer at the Dominion Astrophysical Observatory, shows that the mean radial velocity is -54.9 ± 0.12 km s-1 and the dispersion is 0.86 km s-1 , estimated from 50 constant-velocity stars selected as members. Twenty-five stars (32%) among 78 members are possible radial-velocity variable stars, but no orbits are determined because of the sparse sampling. Seventeen stars are radial-velocity non-members, while membership estimates for six stars are uncertain. There is a hint that the observed velocity dispersion falls off at large radius. The known radial-velocity variables also seem to be more centrally-concentrated than members with constant velocity, suggesting that mass segregation is being detected. | |
| dc.format.extent | 91 pages | |
| dc.identifier.uri | https://hdl.handle.net/1828/17901 | |
| dc.rights | Available to the World Wide Web | en_US |
| dc.title | A Photometric and radial-velocity study of the open cluster NGC 7789 | en_US |
| dc.type | Thesis | en_US |
Files
Original bundle
1 - 1 of 1
Loading...
- Name:
- GIM_Munhwan_MSc_1998_745706.pdf
- Size:
- 12.83 MB
- Format:
- Adobe Portable Document Format