T. R. Wells's research while affiliated with University of Toronto and other places

Publications (7)

Article
Thirteen double-mode RR Lyrae (RRd) stars, with mean magnitudes >B<c = 18.30±0.10 mag and >V<c = 17.80±0.15 mag, have been identified in the variable rich Oosterhoff type I globular cluster IC 4499. The stars have surprisingly uniform properties, and are considerably different from RRd stars found in Oosterhoff type II systems. The mean first-overt...
Article
Observations spanning 52 yr have been used to study the three slow variables in the globular cluster Messier 10. These observations indicate that one of the variables is a semiregular with a periodicity of about 50 days. They also show fluctuations in the periods of the other two variables, well-known Population II Cepheids.
Article
High precision photographic photometry indicates that two stars lying on the giant branch in the C-M diagram of M15 are small amplitude (≡ 0.2 mag) variables. The two stars are Kustner 64 and 152. The existing data is not sufficient for period determination.
Article
The University of Toronto 24-inch telescope at the Las Campanas Observatory of the Carnegie Institution of Washington has beerused for the study of variables in four southern globular clusters: NGC 6273=1119, NGC 6284, NGC 6293 and NGC 6333-M9. The first three of these clusters lie about 2° from one another in the sky at southern declinations rangi...
Article
High precision photographic photometry indicates that two stars lying on the giant branch in the C-M diagram of M15 are small amplitude (~0.2 mag) variables. The two stars are Kustner 64 and 152. This investigation is based on plates taken with three telescopes: the Dominion Astrophysical Observatory 1.8-metre reflector, the David Dunlap 1.9-metre...
Article
Three new variables have been found in NGC 6293. Of 11 variables in and around the cluster, periods have been determined for nine. Five of these are RR Lyrae variables, one is a Cepheid, and three are Mira variables. Four of the RR Lyrae stars may be members. A distance of 7.8 kpc has been determined for NGC 6293.
Article
Five new variables have been found in NGC 6284. Of 15 variables in and around the cluster, periods have been determined for 13. Nine of these are RR Lyrae variables, two are Population II Cepheids, and two are Mira variables. Four of the RR Lyrae stars and both Cepheids may be members. This cluster has the highest metallicity for a cluster with Pop...

Citations

... In the upper left panel of Figure 20, the NGC 2257 RRd stars are compared with the RRd stars in several galactic globular clusters. Since the mid-1980s, in particular the publication of the Clement et al. (1986) , and with two sets of recent theoretical models (lower right panel). The sources of the galactic globular cluster data are as follows: M15 (Sandage et al. 1981;Cox et al. 1983;Nemec 1985b;Purdue et al. 1995;Paparó et al. 1998Paparó et al. , 2002; IC4499 (Clement et al. 1986;Walker & Nemec 1996;Kovács & Walker 1999;A. ...