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- ID:
- ivo://CDS.VizieR/J/ApJ/549/578
- Title:
- BV photometry of Trumpler 14 and 16
- Short Name:
- J/ApJ/549/578
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- H-R diagrams are presented for the very young galactic clusters Trumpler 14 and Trumpler 16, which are the two most populous clusters in the region of vigorous star formation surrounding {eta} Carinae. Point spread function photometry of UBV CCD images is presented down to V~19 for over 560 stars in Tr 16 and 290 stars in Tr 14. We have also obtained similar data for a local background field. After determining cluster membership through proper motions from a previous work, we find that the reddening of cluster members is significantly lower than that of the local background stars. Thus, we are able to use individual reddenings to identify likely members at far deeper levels than possible with proper motions. This work has revealed a significant population of pre-main-sequence (PMS) stars in both clusters. The location of the PMS stars in the H-R diagram indicates that the theoretical "stellar birthline" of Palla & Stahler (1990ApJ...360L..47P, follows the locus of stars far better than that of Beech & Mitalas (1994ApJS...95..517B). Comparison with both pre- and post-main-sequence isochrones also reveals that although intermediate-mass stars have been forming continuously over the last 10Myr, the high-mass stars formed within the last 3Myr. There is no evidence that the formation of the intermediate-mass stars was truncated by the formation of the high-mass stars.
- ID:
- ivo://CDS.VizieR/J/AJ/123/3216
- Title:
- BV photometry of variable stars in SMC
- Short Name:
- J/AJ/123/3216
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- B and V photometry has been obtained for variable stars in the northeast arm of the Small Magellanic Cloud (SMC). Periods and light curves have been determined for 237 periodic variables, including 201 Cepheids, 68 of which are newly discovered. Fundamental-mode Cepheids and first-overtone mode Cepheids are generally well separated in the BV color-magnitude diagram, with the latter having bluer mean colors than the former. The Cepheid period-color relationship for this outlying SMC field is indistinguishable from that seen in more centrally located SMC fields and is bluer than theoretical predictions. The red edge to the populated portion of the instability strip shifts to bluer colors for fainter Cepheids. There is support from our sample for a previously reported steepening in the slope of the period-luminosity relation for fundamental-mode Cepheids near a period of 2 days. The Cepheids of the northeast arm may be closer to us than are those of the main body of the SMC, but the difference is smaller than or equal to about 4kpc, comparable to the tidal radius of the SMC.
- ID:
- ivo://CDS.VizieR/J/AJ/152/120
- Title:
- BV photometry of V532 Mon
- Short Name:
- J/AJ/152/120
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The first two sets of complete charge-coupled device light curves in the B and V bands of the short-period binary system, V532 Mon, are presented. The light curves are analyzed with spot models using the Wilson-Devinney code. V532 Mon is found to be an A-subtype intermediate-contact binary with a degree of contact factor of f=47.1%(+/-2.7%), a mass ratio of q=0.2502(+/-0.0019), and a cool spot on the primary component. The period changes of the system are investigated by combining newly determined times of light minimum with others published in the literature. We found that the general trend of the observed-calculated (O-C) curve shows a downward parabolic variation that corresponds to a long-term decrease in the orbital period at a rate of dP/dt=-1.716(+/-0.002)*10^-7^dyr^-1^. The long-term decrease of the orbital period can be explained by mass transfer from the more-massive component to the less massive one. The long-time period decrease, the intermediate-contact configuration, and the astrophysical parameters of the binary system suggest that V532 Mon will evolve into high fill-out, extreme mass-ratio overcontact binaries.
- ID:
- ivo://CDS.VizieR/J/MNRAS/385/361
- Title:
- BVRcIc photometry of NGC 821 globular clusters
- Short Name:
- J/MNRAS/385/361
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We performed a photometric study of globular clusters around the isolated elliptical galaxy NGC 821. B, V and R-band photometry come from the Mini-Mosaic imager on the 3.5-m Wisconsin Indiana Yale NOAO (WIYN) telescope. Observations were conducted between November 30 - December 2, 2005. Average seeing conditions were ~0.7". Two Hubble Space Telescope (HST) Wide-Field Planetary Camera 2 (WFPC2) fields were analysed in the V and I-bands. Objects in this catalogue are the globular cluster candidates according to the selection criteria detailed in the journal article. Astrometric solution is from USNO-B stars. Note the center of NGC 821 on this system is located at 02:08:21.118 +10:59:42.21. Photometry has been corrected for Galactic extinction and we used a distance modulus of m-M=31.75 in our analysis.
- ID:
- ivo://CDS.VizieR/J/A+A/570/A100
- Title:
- BVRc light curves of 5 CoRoT RR Lyrae stars
- Short Name:
- J/A+A/570/A100
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- High-precision, space-based photometric missions like CoRoT and Kepler have revealed new and surprising phenomena in classical variable stars. Such discoveries were the period doubling in RR Lyrae stars and the frequent occurrence of additional periodicities some of which can be explained by radial overtone modes, but others are discordant with the radial eigenfrequency spectrum. We search for signs of period doubling in CoRoT RR Lyrae stars. The occurrence of this dynamical effect in modulated RR Lyrae stars might help us to gain more information about the mysterious Blazhko effect. The temporal variability of the additional frequencies in representatives of all subtypes of RR Lyrae stars is also investigated.
- ID:
- ivo://CDS.VizieR/J/ApJ/652/458
- Title:
- BVRH{alpha} photometry of candidates Be stars
- Short Name:
- J/ApJ/652/458
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present B, V, R, and H{alpha} photometry of eight clusters in the Small Magellanic Cloud, five in the Large Magellanic Cloud, and three Galactic clusters and use two-color diagrams (2-CDs) to identify candidate Be star populations in these clusters. We find evidence that the Be phenomenon is enhanced in low-metallicity environments, based on the observed fractional early-type candidate Be star content of clusters of age 10-25Myr.
- ID:
- ivo://CDS.VizieR/J/A+A/317/448
- Title:
- BVRHalpha photometry of NGC 1818
- Short Name:
- J/A+A/317/448
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present B,V,R,Halpha CCD photometry and astrometry of Be stars in NGC 1818, its small neighbouring cluster NGC 1818B, and the surrounding field down to V = 18 mag. Our Be star identifiers conform to IAU specifications. For a description of the UBVRI and Halpha systems, see e.g. <GCPD/08> and <GCPD/55>
- ID:
- ivo://CDS.VizieR/J/A+A/445/901
- Title:
- BV(RI)c bands of Cepheids in IC 1613
- Short Name:
- J/A+A/445/901
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A set of six BV(RI)c observations collected with the WFI at the ESO 2.2m telescope have been used to derive multicolor data of Cepheids in IC 1613 identified in previous surveys. Since part of the previously known data were obtained only in V,I filters or without filter (Wh) bands, the method of Freedman has been applied to get reliable mean intensity values of Cepheid magnitudes in the various bands. The resulting slopes of the relations in the BVI bands are similar, within the uncertainties, to those previously obtained by other authors for the LMC. The distribution of the Cepheids in the period-color diagrams is compatible with a change near P about 10d as observed in LMC. The distribution in the color-color diagrams is more similar to that in SMC, and this should be related to the very low metallicity of the galaxy.
- ID:
- ivo://CDS.VizieR/II/208
- Title:
- BVRI CCD photometry in the field of M 31
- Short Name:
- II/208
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Deep BVRI CCD photometry was performed on a 1 square degree region of M31. The observations were made between September 12 and September 27, 1990, using the McGraw-Hill 1.3m telescope at the Michigan-Dartmouth-MIT (MDM) observatory at Kitt Peak. The catalogue has typical completion limits of 22.3Bmag, 22.2Vmag, 22.2Rmag and 20.9Imag. Photometric accuracy is about 2% at Vmag=19. The final astrometric calibrations take into account the systematic error discovered in the Berkhuijsen etal (1987) catalog (Magnier etal 1993). They are in the J2000 system and are eventually tied to the HST Guide Star Catalog. The final photometric calibrations are tied via the NGC 206 region to photometry taken at the Michigan-Dartmouth-MIT (MDM) 1.3m in September and October 1993. These are tied to the Landolt (1992) system of standard stars, and are in the Johnson-Kron-Cousins system (BVRcIc).
