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681. BV phot. of a detached eclipsing binary in M 33
ID:
ivo://CDS.VizieR/J/ApJ/652/313
Title:
BV phot. of a detached eclipsing binary in M 33
Short Name:
J/ApJ/652/313
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present the first direct distance determination to a detached eclipsing binary in M33, which was found by the DIRECT Project. Located in the OB 66 association at coordinates (RA,DE)=(01:33:46.17,+30:44:39.9) for J2000.0, it was one of the most suitable detached eclipsing binaries found by DIRECT for distance determination, given its apparent magnitude and orbital period. We obtained follow-up BV time-series photometry, JHKs photometry, and optical spectroscopy from which we determined the parameters of the system. It contains two O7 main-sequence stars, with masses of 33.4+/-3.5 and 30.0+/-3.3M_{sun}_ and radii of 12.3+/-0.4 and 8.8+/-0.3R_{sun}_, respectively. We derive temperatures of 37000+/-1500 and 35600+/-1500K. Using BVRJHKs photometry for the flux calibration, we obtain a distance modulus of 24.92+/-0.12mag (964+/-54kpc), which is 0.3mag longer than the Key Project distance to M33. We discuss the implications of our result and the importance of establishing M33 as an independent rung on the cosmological distance ladder.
682. BV photometry and Li abundances in NGC3960
ID:
ivo://CDS.VizieR/J/A+A/475/539
Title:
BV photometry and Li abundances in NGC3960
Short Name:
J/A+A/475/539
Date:
21 Oct 2021
Publisher:
CDS
Description:
Old open clusters are very useful targets to investigate mechanisms responsible for lithium (Li) depletion during the main sequence. Comparison of the Li abundances in clusters of different age allows us to understand the efficiency of the Li destruction process. To determine the membership and Li abundance in a sample of candidate members of the open cluster NGC 3960 (age ~1Gyr), aiming to fill the gap between 0.6 and 2Gyr in the empirical description of the behavior of the average Li abundance as a function of the stellar age. We use VLT/FLAMES Giraffe spectra to determine the radial velocities and thus the membership of a sample of 113 photometrically selected candidate cluster members. From the analysis of the Li line we derive Li abundances for both cluster members and non-members. 39 stars have radial velocities consistent with membership, with an expected fraction of contaminating field stars of about 20%. Li is detected in 29 of the radial velocity members; we consider these stars as cluster members, while we make the reasonable assumption that the remaining 10 radial velocity members without Li are among the contaminating stars. Li abundances of the stars hotter than about 6000K are similar to those of stars in the Hyades, while they are slightly smaller for cooler stars. This confirms that NGC 3960 is older than the Hyades. The average Li abundance of stars cooler than about 6000K indicates that the Li Pop. I plateau might start at ~1Gyr, rather than 2Gyr, which is the upper limit previously derived in the literature. We also find that the fraction of field stars with high Li abundance (>1.5) is about one third of the whole sample, which is in agreement with previous estimates. The fraction of contaminating field stars is consistent with that previously derived by us from photometry.
683. BV photometry for components of HIP doubles
ID:
ivo://CDS.VizieR/J/A+A/356/141
Title:
BV photometry for components of HIP doubles
Short Name:
J/A+A/356/141
Date:
21 Oct 2021
Publisher:
CDS
Description:
Using observations obtained with the Tycho instrument of the ESA Hipparcos satellite, a two-colour photometry is produced for components of more than 7000 Hipparcos double and multiple stars with angular separations 0.1 to 2.5 arcsec. We publish 9473 components of 5173 systems with separations above 0.3 arcsec. The majority of them did not have Tycho photometry in the Hipparcos catalogue. The magnitudes are derived in the Tycho B_T and V_T passbands, similar to the Johnson passbands. Photometrically resolved components of the binaries with statistically significant trigonometric parallaxes can be put on an HR diagram, the majority of them for the first time.
684. BV photometry in and around 5 globular clusters
ID:
ivo://CDS.VizieR/J/AJ/147/155
Title:
BV photometry in and around 5 globular clusters
Short Name:
J/AJ/147/155
Date:
21 Oct 2021
Publisher:
CDS
Description:
Homogeneous B, V photometry is presented for 19324 stars in and around 5 Magellanic Cloud globular clusters: NGC 1466, NGC 1841, NGC 2210, NGC 2257, and Reticulum. The photometry is derived from eight nights of CCD imaging with the Cerro Tololo Inter-American Observatory 0.9m SMARTS telescope. Instrumental magnitudes were transformed to the Johnson B, V system using accurate calibration relations based on a large sample of Landolt-Stetson equatorial standard stars, which were observed on the same nights as the cluster stars. Residual analysis of the equatorial standards used for the calibration, and validation of the new photometry using Stetson's sample of secondary standards in the vicinities of the five Large Magellanic Cloud clusters, shows excellent agreement with our values in both magnitudes and colors. Color-magnitude diagrams reaching to the main-sequence turnoffs at V~22mag, sigma-magnitude diagrams, and various other summaries are presented for each cluster to illustrate the range and quality of the new photometry. The photometry should prove useful for future studies of the Magellanic Cloud globular clusters, particularly studies of their variable stars.
685. (BV) photometry in Carina dSph
ID:
ivo://CDS.VizieR/J/A+A/572/A10
Title:
(BV) photometry in Carina dSph
Short Name:
J/A+A/572/A10
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present deep photometry of the Carina dwarf Spheroidal galaxy in the B,V filters from CTIO/MOSAIC, out to and beyond the tidal radius of r_ell_~0.48{deg}. The accurately calibrated photometry is combined with spectroscopic metallicity distributions of Red Giant Branch stars to determine the detailed star formation and chemical evolution history of Carina. The star formation history confirms the episodic formation history of Carina and quantifies the duration and strength of each episode in great detail, as a function radius from the centre. Two main episodes of star formation occurred at old (>8Gyr) and intermediate (2-8Gyr) ages, both enriching stars starting from low metallicities ([Fe/H]<-2dex). By dividing the SFH into two components, we determine that 60+/-9 percent of the total number of stars formed within the intermediate age episode. Furthermore, within the tidal radius (0.48{deg} or 888pc) a total mass in stars of 1.07+/-0.08x10^6^M_{sun}_ was formed, giving Carina a stellar mass-to-light ratio of 1.8+/-0.8. Combining the detailed star formation history with spectroscopic observations of RGB stars, we are able to determine the detailed age-metallicity relation of each episode and the timescale of alpha-element evolution of Carina from individual stars. The oldest episode displays a tight age-metallicity relation during ~6Gyr with steadily declining alpha-element abundances and a possible alpha-element knee visible at [Fe/H]~-2.5dex. The intermediate age sequence displays a more complex age-metallicity relation starting from low metallicity and a sequence in alpha-element abundances with a slope much steeper than observed in the old episode, starting from [Fe/H]=-1.8dex and [Mg/Fe]~0.4dex and declining to Mg-poor values ([Mg/Fe]<-0.5dex). This indicates clearly that both episodes of star formation formed from gas with different abundance patterns , inconsistent with simple evolution in an isolated system.
686. BV photometry in Carina dwarf galaxy
ID:
ivo://CDS.VizieR/J/AJ/115/1840
Title:
BV photometry in Carina dwarf galaxy
Short Name:
J/AJ/115/1840
Date:
21 Oct 2021
Publisher:
CDS
Description:
We have analyzed deep B and V photometry of the Carina dwarf spheroidal galaxy reaching below the old main-sequence turnoff to V~25. Using simulated color-magnitude diagrams to model a range of star formation scenarios, we have extracted a detailed, global star formation history. Carina experienced three significant episodes of star formation at ~15, 7, and 3Gyr. Contrary to the generic picture of galaxy evolution, however, the bulk of star formation, at least 50%, occurred during the episode 7Gyr ago, which may have lasted as long as 2Gyr. For unknown reasons, Carina formed only 10%-20% of its stars at an ancient epoch and then remained quiescent for more than 4 Gyr. The remainder (~30%) formed relatively recently, only 3Gyr ago. Interest in the local population of dwarf galaxies has increased lately because of their potential importance in the understanding of faint galaxy counts. We surmise that objects like Carina, which exhibits the most extreme episodic behavior of any of the dwarf spheroidal companions to the Galaxy, are capable of contributing to the observed excess of blue galaxies at B~24 only if the star formation occurred instantaneously.
687. BV photometry in Draco molecular cloud
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.
688. BV photometry in 4 fields of 47 Tuc
ID:
ivo://CDS.VizieR/J/PASP/99/739
Title:
BV photometry in 4 fields of 47 Tuc
Short Name:
J/PASP/99/739
Date:
21 Oct 2021
Publisher:
CDS
Description:
CCD photometry in B and V, taken with the RCA camera at the CTIO 4-meter telescope, is reported for 8800 stars in the field of 47 Tuc (= NGC 104 = C0021-723). Our data, reduced through the DAOPHOT code, comprise results from two long-exposure frame pairs in which the photometry extends from the cluster turnoff down to V~24, and two other short-exposure fields nearer to the cluster center which precisely define the giant and horizontal branches. Color-magnitude diagrams are presented, statistically corrected for background contamination from the Small Magellanic Cloud halo, and a composite CMD and luminosity function are constructed for the entire cluster, covering an 11-magnitude range in luminosity.
689. BV photometry in five SMC clusters
ID:
ivo://CDS.VizieR/J/AJ/116/2395
Title:
BV photometry in five SMC clusters
Short Name:
J/AJ/116/2395
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present our analysis of archival Hubble Space Telescope Wide Field Planetary Camera 2 (WFPC2) observations in F450W (~B) and F555W (~V) of the intermediate-age populous star clusters NGC 121, NGC 339, NGC 361, NGC 416, and Kron 3 in the Small Magellanic Cloud. We use published photometry of two other SMC populous star clusters, Lindsay 1 and Lindsay 113, to investigate the age sequence of these seven star clusters in order to improve our understanding of the formation chronology of the SMC. We analyzed the V versus B-V and M_V_ versus (B-V)_0_ color-magnitude diagrams of these populous Small Magellanic Cloud star clusters using a variety of techniques and determined their ages, metallicities, and reddenings. These new data enable us to improve the age-metallicity relation of star clusters in the Small Magellanic Cloud. In particular, we find that a closed-box continuous star formation model does not reproduce the age-metallicity relation adequately. However, a theoretical model punctuated by bursts of star formation is in better agreement with the observational data presented herein.
690. BV photometry in Fornax globulars
ID:
ivo://CDS.VizieR/J/AJ/111/1596
Title:
BV photometry in Fornax globulars
Short Name:
J/AJ/111/1596
Date:
21 Oct 2021
Publisher:
CDS
Description:
We report new color-magnitude diagrams for Fornax globular clusters 1 and 5 where our data reaches V=24, below the horizontal branch. Using the index B-R/(B+V+R), a measure of the horizontal branch color, we find cluster 1 has a red (-0.50+/-0.10) and cluster 5 an intermediate color (-0.09+/-0.12) horizontal branch confirming the first extragalactic second parameter pair. The HB types are markedly redder than the Galactic globular clusters at [Fe/H]=-2. In globular cluster 1, we find 21 possible variable stars out of 41 horizontal branch stars. Cluster 1 has an anomalously low ratio of horizontal branch to red giant stars, which formally gives a helium abundance of 0.16<Y<0.22, depending on the assumptions used. For both clusters 1 and 5, and for the red horizontal branch in the field adjacent to cluster 5, V_HB = 21.25 +/- 0.05. We give calibrated surface brightness profiles and measure new core and tidal radii for cluster 1 of 17.6" and 104" and for cluster 5 of <2" and 91", respectively.