- ID:
- ivo://CDS.VizieR/J/A+A/364/712
- Title:
- BV photometry in Draco molecular cloud
- Short Name:
- J/A+A/364/712
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- To investigate the distance and linear dimensions of the Draco Molecular Cloud (MBM 41) we have obtained new CCD photometry for a selection of stars in 20 selected areas toward the cores of the cloud. The selected areas were chosen to coincide with the brightest IRAS emitting portions of the cloud, and also with dense ^12^CO emission from the cloud. For each area we have obtained V and B photometry, and a subset of the fields has also been observed through a narrow-band H{alpha} filter and in the U band. We present V and B magnitudes for the 362 stars which have high-quality observations in both bands. The observations were made during the nights of June 29 and June 30, 1993 at the Palomar Observatory, using the 1.5-meter telescope and Palomar 6 Tektronix CCD camera with 24 micron pixels.
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Search Results
- ID:
- ivo://CDS.VizieR/J/ApJ/710/1664
- Title:
- BV photometry in Leo IV and Leo V dSphs
- Short Name:
- J/ApJ/710/1664
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have obtained deep photometry in two 1{deg}x1{deg} fields covering the close pair of dwarf spheroidal galaxies Leo IV and Leo V and part of the area in between. From the distribution of likely red giant branch (RGB) and horizontal-branch (HB) stars in the data set, we find that both Leo IV and Leo V are significantly larger than indicated by previous measurements based on shallower data. With a half-light radius of r_h_=4.6'+/-0.8' (206+/-36pc) and r_h_=2.6'+/-0.6' (133+/-31pc), respectively, both systems are now well within the physical size bracket of typical dwarf spheroidal Milky Way satellites. Both are also found to be significantly elongated with an ellipticity of {epsilon}~0.5, a characteristic shared by many of the fainter (M_V_>-8) Milky Way dwarf spheroidals. The large spatial extent of our survey allows us to search for extra-tidal features in the area between the two dwarf galaxies with unprecedented sensitivity. The spatial distribution of candidate RGB and HB stars in this region is found to be non-uniform at the ~3{sigma} level. We investigate different scenarios to explain the close proximity of Leo IV and Leo V, and the possible tidal bridge between them.
- ID:
- ivo://CDS.VizieR/J/AJ/117/2868
- Title:
- BV photometry in M2 (NGC 7089)
- Short Name:
- J/AJ/117/2868
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present BV CCD photometry for 30 RR Lyrae variables, including 13 newly discovered, in the Oosterhoff type II globular cluster M2. New light curves and ephemerides are presented. Our observations cover magnitudes ranging from the red giant branch tip to ~3mag below the turnoff, allowing us to determine accurate fundamental photometric parameters. With the discovery of new RR Lyrae variables, the mean periods of the RRab and RRc variables are <P_ab_>=0.685+/-0.022days and <P_c_>=0.333+/-0.013days, respectively. The number ratio of the RRc type variables to the total number of RR Lyrae type variables is n(c)/n(ab+c)=0.40. The RR Lyrae pulsational mode transition occurs between the fundamental period of 0.528-days and 0.556-days. From star counts along the horizontal branch (HB), we obtain two HB color distribution indices, (B-R)/(B+V+R)=0.92 and B2/(B+V+R)=0.46. The period-change rates are also derived. The mean period-change rate from six RRab variables is <{beta}>=0.06+/-0.04days/Myr, which agrees well with the predictions of Lee's 1991 model. Our color-magnitude diagram shows a very extended blue HB tail, and there are no significant blue HB gaps in M2.
- ID:
- ivo://CDS.VizieR/J/AJ/121/318
- Title:
- BV photometry in NGC 5986
- Short Name:
- J/AJ/121/318
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have obtained new CCD BV photometry of the little-studied southern Galactic globular cluster NGC 5986, including light curves of five of its RR Lyrae variables. The cluster's red giant branch bump is detected for the first time, at V=16.47 +/-0.03. We derive a reddening and true distance modulus of E(B-V)=0.29+/-0.02 and (m-M)_0_=15.15+/-0.10, respectively. The cluster's color-magnitude diagram reveals a mostly blue horizontal branch, like that of M13 or M2, and quite unlike M3; yet all of these clusters have nearly identical metallicities ([Fe/H]_CG97_=-1.35). We show that the RR Lyrae variables in NGC 5986 are about 0.2mag brighter on average than those in M3, an important exception to the often-employed, universal M_V_(RR)-[Fe/H] relation. Finally, we note that NGC 5986 contains two luminous stars with spectral types A-F, which are likely to be post-asymptotic giant branch (PAGB) objects. The V-band luminosity function of such yellow PAGB stars is a promising standard candle. We suggest that the luminosity function is sharply peaked at M_V_(PAGB)=-3.28+/-0.07.
- ID:
- ivo://CDS.VizieR/J/A+A/328/167
- Title:
- BV photometry in supergiant shell LMC4
- Short Name:
- J/A+A/328/167
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The youngest stellar populations of a 'J'-shaped region inside the supergiant shell (SGS) LMC4 have been analysed with CCD photometry in B, V passbands. This region consists of 2 coherent strips, one from the east to the west reaching about 400pc across the OB superassociation LH 77 and another extending about 850pc from south to north. The standard photometric methods yield for each of the 25 CCD fields a colour-magnitude diagram (CMD) which is used for age determination of the youngest star population by isochrone fitting. The resultant ages lie in the range from 9Myr to 16Myr without correlation with the distance to the LMC 4 centre. We therefore conclude that there must have been one triggering event for star formation inside this large LMC SGS with a diameter of 1.4kpc.
- ID:
- ivo://CDS.VizieR/J/AZh/79/542
- Title:
- BV photometry of active K-M dwarfs
- Short Name:
- J/AZh/79/542
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Variability of the photospheric radiation of 40 (dKe-dMe) dwarfs due to variations in the spottedness of their surfaces is analyzed based on the behavior of their mean annual brightnesses over long time intervals.
- ID:
- ivo://CDS.VizieR/J/AJ/127/318
- Title:
- BV photometry of Andromeda II variables
- Short Name:
- J/AJ/127/318
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results of a variable star search in Andromeda II, a dwarf spheroidal galaxy companion to M31, using Hubble Space Telescope Wide Field Planetary Camera 2 observations. Seventy-three variables were found, one of which is an anomalous Cepheid while the others are RR Lyrae stars. The anomalous Cepheid has properties consistent with those found in other dwarf spheroidal galaxies. For the RR Lyrae stars, the mean periods are 0.571 and 0.363 days for the fundamental mode and first-overtone mode stars, respectively. With this fundamental mode mean period and the mean metallicity determined from the red giant branch (<[Fe/H]>=-1.49), Andromeda II follows the period-metallicity relation defined by the Galactic globular clusters and other dwarf spheroidal galaxies. We also find that the properties of the RR Lyrae stars themselves indicate a mean abundance that is consistent with that determined from the red giants.
- ID:
- ivo://CDS.VizieR/J/A+A/616/A40
- Title:
- BV photometry of Bochum 7 members
- Short Name:
- J/A+A/616/A40
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We plan to identify the members of the Bochum 7 association by performing simultaneous astrometric and spectrophotometric analyses, and estimate its distance and evolutionary stage. We used our own visual spectroscopic and UBV photometric data of a 30{deg}x30{deg} region centered at RA=8:44:47.2, DE=-45:58:55.5. This information enabled us to estimate the spectral classification and distance of all stars present in the region. The proper motion was analyzed with data of the UCAC 5 catalog and was used to identify the members of this association. We added JHK data from 2MASS and IRAS catalogs to check for the presence of infrared (IR) excess stars. We found that Bochum 7 is an OB association with at least 27 identified stellar members (l=265.12{deg}, b=-2{deg}) at a distance of ~=5640pc. Its proper motion is pm_RA_cosDE=-4.92+/-0.08mas/yr, pm_DE_=3.26+/-0.08mas/yr. We derived an average heliocentric radial velocity of ~35km/s and were able to confirm the binary nature of the (ALS 1135) system and detect four new binary star candidates. Analysis of data for massive Bo 7 star candidates points towards a young age (<=3x10^6^ years old) for the association, although the presence of a previous episode of star formation remains to be analyzed.
- ID:
- ivo://CDS.VizieR/J/AJ/146/141
- Title:
- BV photometry of dwarf Cepheids in Carina
- Short Name:
- J/AJ/146/141
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report the detection of 388 pulsating variable stars (and some additional miscellaneous variables) in the Carina dwarf spheroidal galaxy over an area covering the full visible extent of the galaxy and extending a few times beyond its photometric (King) tidal radius along the direction of its major axis. Included in this total are 340 newly discovered dwarf Cepheids (DCs), which are mostly located ~2.5mag below the horizontal branch and have very short periods (<0.1days), typical of their class and consistent with their location on the upper part of the extended main sequence of the younger populations of the galaxy. Several extra-tidal DCs were found in our survey up to a distance of ~1{deg} from the center of Carina. Our sample also includes RR Lyrae stars and anomalous Cepheids, some of which were found outside the galaxy's tidal radius as well. This supports past works that suggest that Carina is undergoing tidal disruption. We use the period-luminosity relationship for DCs to estimate a distance modulus of {mu}_0_=20.17+/-0.10mag, in very good agreement with the estimate from RR Lyrae stars. We find some important differences in the properties of the DCs of Carina and those in Fornax and the LMC, the only extragalactic samples of DCs currently known. These differences may reflect a metallicity spread, depth along the line of sight, and/or different evolutionary paths of the DC stars.
- ID:
- ivo://CDS.VizieR/J/A+A/448/171
- Title:
- BV photometry of 3 globular clusters
- Short Name:
- J/A+A/448/171
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Some of the Galactic outer halo globular clusters are excellent tools to probe gravitational theories in the regime of weak accelerations. The measurement of the line-of-sight velocity dispersion among stars in these clusters will differentiate between the validity of Newtonian dynamics (low velocity dispersion) and the possibility of modified Newtonian dynamics (MOND) or dark matter dominated globular clusters (high velocity dispersion). In this paper, the properties of probable member stars of the three best-case gravitational theory-testing clusters AM 1, Pal 3 and Pal 14 are presented. The member selection is based on VLT photometry in Johnson BV. The positions of the stars were determined with an accuracy of the order of <=0.2", allowing their direct use for follow-up spectroscopy. The distance, reddening, age and metallicities of the clusters were estimated from isochrone fitting. Furthermore, improved structural parameters, like central coordinates, ellipticity, half-light radius, King model core and tidal radius, are presented.
