Number of results to display per page
Search Results
- ID:
- ivo://CDS.VizieR/J/AJ/121/861
- Title:
- BVI photometry of central part of M33
- Short Name:
- J/AJ/121/861
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The DIRECT project aims to determine direct distances to two important galaxies in the cosmological distance ladder - M31 and M33 - using detached eclipsing binaries (DEBs) and Cepheids. The search for these variables requires time-series photometry of large areas of the target galaxies and yields magnitudes and positions for tens of thousands of stellar objects, which may be of use to the astronomical community at large. During the first phase of the project, between 1996 September and 1997 October, we were awarded 95 nights on the F. L. Whipple Observatory 1.2 m telescope and 36 nights on the Michigan-Dartmouth-MIT 1.3 m telescope to search for DEBs and Cepheids in the M31 and M33 galaxies. This paper, the first in our series of stellar catalogs, lists the positions, three-color photometry, and variability indices of 57,581 stars with 14.4<V<23.6 in the central part of M33. The catalog is available from our FTP site.
- ID:
- ivo://CDS.VizieR/J/ApJ/743/176
- Title:
- BVI photometry of Cepheids in M81
- Short Name:
- J/ApJ/743/176
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We identify and phase a sample of 107 Cepheids with 10days<P<100days in M81 (NGC 3031) using the Large Binocular Telescope and calibrate their B, V, and I mean magnitudes with archival Hubble Space Telescope (HST) data. The use of a ground-based telescope to identify and phase the Cepheids and HST only for the final calibration reduces the demand on this highly oversubscribed spacecraft by nearly an order of magnitude and yields period-luminosity (PL) relations with dispersions comparable to the best LMC samples. We fit the sample using the OGLE-II LMC PL relations and are unable to find a self-consistent distance for different band combinations or radial locations within M81. We find a distance modulus for M81, relative to the LMC, of {mu}M_81_-{mu}_LMC_=9.39+/-0.14mag, including uncertainties due to the metallicity corrections. This corresponds to a distance to M81 of 3.6+/-0.2Mpc, assuming an LMC distance modulus of 18.41mag.
- ID:
- ivo://CDS.VizieR/J/A+AS/131/1
- Title:
- BVI photometry of 5 CVn cloud galaxies
- Short Name:
- J/A+AS/131/1
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present results of CCD imaging in B, V of five late-type galaxies with radial velocities V_0_<350km/s in the Canes Venatici cloud. Based on the photometry of their brightest blue stars we derived the following distances to the galaxies: 9.7Mpc for NGC 4144, 4.5Mpc for NGC 4244, 4.2Mpc for NGC 4395, 2.9Mpc for NGC 4449, and 8.2Mpc for UGC 8331.
- ID:
- ivo://CDS.VizieR/J/AJ/141/92
- Title:
- BVI photometry of 10 distant open clusters
- Short Name:
- J/AJ/141/92
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The oldest open star clusters are important for tracing the history of the Galactic disk, but many of the more distant clusters are heavily reddened and projected against the rich stellar background of the Galaxy. We have undertaken an investigation of several distant clusters (Berkeley 19, Berkeley 44, King 25, NGC 6802, NGC 6827, Berkeley 52, Berkeley 56, NGC 7142, NGC 7245, and King 9) to develop procedures for separating probable cluster members from the background field. We next created a simple quantitative approach for finding approximate cluster distances, reddenings, and ages. We first conclude that with the possible exception of King 25 they are probably all physical clusters.
- ID:
- ivo://CDS.VizieR/J/A+A/544/A73
- Title:
- BVI photometry of Fornax dSph galaxy
- Short Name:
- J/A+A/544/A73
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present deep photometry in the B,V and I filters from CTIO/MOSAIC for about 270.000 stars in the Fornax dwarf Spheroidal galaxy, out to a radius of r_ell_~0.8{deg}. By combining the accurately calibrated photometry with the spectroscopic metallicity distributions of individual Red Giant Branch stars we obtain the detailed star formation and chemical evolution history of Fornax. Fornax is dominated by intermediate age (1-10Gyr) stellar populations, but also includes ancient (10-14Gyr), and young (<1Gyr) stars. We show that Fornax displays a radial age gradient, with younger, more metal-rich populations dominating the central region. This confirms results from previous works. Within an elliptical radius of 0.8 degrees, or 1.9kpc from the centre, a total mass in stars of 4.3*10^7^M_{sun}_ was formed, from the earliest times until 250Myr ago. Using the detailed star formation history, age estimates are determined for individual stars on the upper RGB, for which spectroscopic abundances are available, giving an age-metallicity relation of the Fornax dSph from individual stars. This shows that the average metallicity of Fornax went up rapidly from [Fe/H]<-2.5dex to [Fe/H]=-1.5dex between 8-12Gyr ago, after which a more gradual enrichment resulted in a narrow, well-defined sequence which reaches [Fe/H]~-0.8dex, ~3Gyr ago. These ages also allow us to measure the build-up of chemical elements as a function of time, and thus determine detailed timescales for the evolution of individual chemical elements. A rapid decrease in [Mg/Fe] is seen for the stars with [Fe/H]>-1.5dex, with a clear trend in age.
- ID:
- ivo://CDS.VizieR/J/A+A/404/423
- Title:
- BVI photometry of Galactic Cepheids
- Short Name:
- J/A+A/404/423
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- 321 Galactic fundamental-mode Cepheids with good B,V,I photometry by Berdnikov et al. (2000, Cat. <J/A+AS/143/211>) and with homogenized color excesses E(B-V) based on Fernie et al. (1995IBVS.4148....1F) are used to determine their period-colour relation in the range 0.4<log P<1.6. Distances of 25 Cepheids in open clusters (Feast, 1999PASP..111..775F) and of 28 Cepheids with BBW distances (Gieren et al., 1998ApJ...496...17G) are used in a first step to determine the absorption coefficients R_B_=4.17, R_V_=3.17, and R_I_=1.89. The two sets define two independent P-L relations which agree very well in slope. They are therefore combined into a single mean Galactic P-L relation.
- ID:
- ivo://CDS.VizieR/J/A+A/430/603
- Title:
- BVI photometry of LMC bar variables
- Short Name:
- J/A+A/430/603
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the Johnson-Cousins B,V and I time series data obtained for 162 variable stars (135 RR Lyrae, 4 candidate Anomalous Cepheids, 11 Classical Cepheids, 11 eclipsing binaries and 1 delta Scuti star) in two 13x13 square arcmin areas close to the bar of the Large Magellanic Cloud. The photometric observations presented in this paper were carried out at the 1.54m Danish telescope located in La Silla, Chile, on the nights 4-7 January 1999, UT, and 23-24 January 2001, UT, respectively. In the paper we give coordinates, finding charts, periods, epochs, amplitudes, and mean quantities (intensity- and magnitude-averaged luminosities) of the variables with full coverage of the light variations, along with a discussion of the pulsation properties of the RR Lyrae stars in the sample.
- ID:
- ivo://CDS.VizieR/J/MNRAS/361/1055
- Title:
- BVI photometry of LMC Be stars
- Short Name:
- J/MNRAS/361/1055
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a catalogue with coordinates and photometric data of 2446 Be star candidates in the Large Magellanic Cloud (LMC), based on a search of the OGLE II data base. The I-band light curves of these stars show outbursts in 24% of the sample (Type-1 stars), high and low states in 10%, periodic variations in 6% (Type-3 stars), and stochastic variations in 60% of the cases. We report on the result of the statistical study of light curves of Type-1 and Type-3 stars in the LMC, and the comparison with the previously reported results of the Small Magellanic Cloud (SMC) sample.
- ID:
- ivo://CDS.VizieR/J/MNRAS/349/1278
- Title:
- BVI photometry of M22
- Short Name:
- J/MNRAS/349/1278
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present wide field photometry of the Galactic Globular Cluster M 22 in the B, V and I passbands for more than 186,000 stars. The study is complemented by the photometry in two narrowband filters centered on H{alpha} and the adjacent continuum, and by infrared J, H and K magnitudes derived from the 2 MASS survey for ~2000 stars. Profiting from this huge database, we completely characterized the evolved stellar sequences of the cluster by determining a variety of photometric parameters, including new photometric estimates of the mean metallicity, reddening and distance to the cluster. In particular, from our multi-wavelength analysis, we re-examined the long-standing metallicity spread problem in M 22. According to our dataset, we conclude that most of the observed width of the red giant branch must be due to differential reddening, which amounts to a maximum of {Delta}E(B-V)~0.06, although the presence of a small metallicity spread cannot be completely ruled out. More specifically, the maximum metallicity spread allowed by our data is of the order of {Delta}[Fe/H]~0.1-0.2dex, i.e., not much more than what allowed by the photometric errors. Finally, we identified most of the known variable stars and peculiar objects in our field of view. In particular, we find additional evidence supporting previous optical identifications of the central star of the Planetary Nebula IRAS 18333-2357, which is associated with M 22.
