- ID:
- ivo://CDS.VizieR/J/A+A/531/A92
- Title:
- Deep all-sky census of the Hyades
- Short Name:
- J/A+A/531/A92
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- On the basis of the PPMXL catalogue we perform an all-sky census of the Hyades down to masses of about 0.2M_{sun}_ in a region up to 30pc from the cluster centre. We use the proper motions from PPMXL in the convergent point method to determine probable kinematic members. From 2MASS photometry and CMC14 r'-band photometry, we derive empirical colour-absolute magnitude diagrams and, finally, determine photometric membership for all kinematic candidates. This is the first deep (r'<17) all-sky survey of the Hyades allowing a full three-dimensional analysis of the cluster. The survey is complete down to at least M_{K_s_}_=7.3 or 0.25M_{sun}_. We find 724 stellar systems co-moving with the bulk Hyades space velocity, which represent a total mass of 435M_{sun}_. The tidal radius is about 9pc, and 275M_{sun}_ (364 systems) are gravitationally bound. This is the cluster proper. Its mass density profile is perfectly fitted by a Plummer model with a central density of 2.21M_{sun}_/pc^3^ and a core radius of r_co_=3.10pc, while the half-mass radius is r_h_=4.1pc. There are another 100M_{sun}_ in a volume between one and two tidal radii (halo), and another 60M_{sun}_ up to a distance of 30pc from the centre. Strong mass segregation is inherent in the cluster. The present-day luminosity and mass functions are noticeably different in various parts of the cluster (core, corona, halo, and co-movers). They are strongly evolved compared to presently favoured initial mass functions. The analysis of the velocity dispersion of the cluster shows that about 20% of its members must be binaries. As a by-product, we find that presently available theoretical isochrones are not able to adequately describe the near-infrared colour-absolute magnitude relation for those cluster stars that are less massive than about 0.6M_{sun}_.
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Search Results
- ID:
- ivo://CDS.VizieR/J/ApJ/654/915
- Title:
- Deep FORS1 BR photometry of omega Cen
- Short Name:
- J/ApJ/654/915
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results of a deep photometric survey performed with the VLT FORS1 aimed at investigating the complex main-sequence structure of the stellar system Centauri. We confirm the presence of a double main sequence and identify its blue component (bMS) over a large field of view up to 26' from the cluster center. We found that bMS stars are significantly more concentrated toward the cluster center than the other "normal" MS stars. The bMS morphology and its position in the CMD have been used to constrain the helium overabundance required to explain the observed MS morphology.
- ID:
- ivo://CDS.VizieR/J/ApJ/891/81
- Title:
- Deep optical and infrared photometry of Sh2-305
- Short Name:
- J/ApJ/891/81
- Date:
- 17 Jan 2022 00:38:10
- Publisher:
- CDS
- Description:
- Using our deep optical and near-infrared photometry along with multiwavelength archival data, we here present a detailed study of the Galactic HII region Sh 2-305 to understand the star/star-cluster formation. On the basis of excess infrared emission, we have identified 116 young stellar objects (YSOs) within a field of view of ~18.5'x18.5' around Sh 2-305. The average age, mass, and extinction (AV) for this sample of YSOs are 1.8Myr, 2.9M_{sun}_, and 7.1mag, respectively. The density distribution of stellar sources along with minimal spanning tree calculations on the location of YSOs reveals at least three stellar subclusterings in Sh 2-305. One cluster is seen toward the center (i.e., Mayer 3), while the other two are distributed toward the north and south directions. Two massive O-type stars (VM2 and VM4; ages ~5Myr) are located at the center of the Sh 2-305 HII region. The analysis of the infrared and radio maps traces the photon-dominant regions (PDRs) in Sh 2-305. The association of the younger generation of stars with the PDRs is also investigated in Sh2-305. This result suggests that these two massive stars might have influenced the star formation history in Sh 2-305. This argument is also supported by the calculation of various pressures driven by massive stars, the slope of the mass function/K-band luminosity function, star formation efficiency, fraction of Class I sources, and mass of the dense gas toward the subclusterings in Sh 2-305.
- ID:
- ivo://CDS.VizieR/J/A+A/324/549
- Title:
- Deep UVBRI photometry in IC 348
- Short Name:
- J/A+A/324/549
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Table3 contains UBVRI-CCD photometry for the 123 observed stars in the nucleus of IC 348 open cluster. Magnitude and colours are given with their corresponding errors. Column "N" gives the number of observations. Spectral types and cross-identifications with other catalogues are given in note file. Table5 contains adopted reddening solution for the brightest members in IC 348
315. Delta Scuti stars
- ID:
- ivo://CDS.VizieR/J/A+AS/144/469
- Title:
- Delta Scuti stars
- Short Name:
- J/A+AS/144/469
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- An extensive and up-dated list of {delta} Sct stars is presented here. More than 500 papers, published during the last few years, have been revised and 341 new variables have been added to our last list, six years ago. This catalogue is intended to be a comprehensive review on the observational characteristics of all the {delta} Sct stars known until now, including stars contained in earlier catalogues together with other new discovered variables, covering information published until January 2000. In summary, 636 variables, 1149 references and 182 individual notes are presented in this new list.
- ID:
- ivo://CDS.VizieR/J/ApJ/872/85
- Title:
- Detached eclipsing binaries with Gaia parallaxes
- Short Name:
- J/ApJ/872/85
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Using a sample of 81 Galactic, detached eclipsing binary stars we investigated the global zero-point shift of their parallaxes with the Gaia Data Release 2 (DR2) parallaxes. The stars in the sample lay in a distance range of 0.04-2kpc from the Sun. The photometric parallaxes {omega}_Phot_ of the eclipsing binaries were determined by applying a number of empirical surface brightness-color (SBC) relations calibrated on optical-infrared colors. For each SBC relation we calculated the individual differences d{varpi}_i_=({varpi}_Gaia_-{varpi}_Phot_)_i_ and then we calculated unweighted and weighted means. As the sample covers the whole sky we interpret the weighted means as the global shifts of the Gaia DR2 parallaxes with respect to our eclipsing binary sample. Depending on the choice of the SBC relation the shifts vary from -0.094 to -0.025mas. The weighted mean of the zero-point shift from all colors and calibrations used is d{omega}=-0.054+/-0.024mas. However, the SBC relations based on (B-K) and (V-K) colors, which are the least reddening dependent and have the lowest intrinsic dispersions, give a zero-point shift of d{omega}=-0.031+/-0.011mas in full agreement with results obtained by Lindegren+ (2018A&A...616A...2L) and Arenou+ (2018A&A...616A..17A). Our result confirms the global shift of Gaia DR2 parallaxes of d{omega}=-0.029mas reported by the Gaia team, but we do not confirm the larger zero-point shift reported by a number of follow-up papers.
- ID:
- ivo://CDS.VizieR/J/ApJS/190/77
- Title:
- Detailed analysis of cool WDs in the SDSS
- Short Name:
- J/ApJS/190/77
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present optical spectroscopy and near-infrared photometry of 126 cool white dwarfs (WDs) in the Sloan Digital Sky Survey (SDSS DR3). Our sample includes high proper motion targets selected using the SDSS and USNO-B astrometry and a dozen previously known ultracool WD candidates. Our optical spectroscopic observations demonstrate that a clean selection of large samples of cool WDs in the SDSS (and the SkyMapper, Pan-STARRS, and the Large Synoptic Survey Telescope data sets) is possible using a reduced proper motion diagram and a tangential velocity cut-off (depending on the proper motion accuracy) of 30km/s. Our near-infrared observations reveal eight new stars with significant absorption. We use the optical and near-infrared photometry to perform a detailed model atmosphere analysis. More than 80% of the stars in our sample are consistent with either pure hydrogen or pure helium atmospheres. However, the eight stars with significant infrared absorption and the majority of the previously known ultracool WD candidates are best explained with mixed hydrogen and helium atmosphere models. The age distribution of our sample is consistent with a Galactic disk age of 8Gyr. A few ultracool WDs may be as old as 12-13Gyr, but our models have problems matching the spectral energy distributions of these objects. There are only two halo WD candidates in our sample. However, trigonometric parallax observations are required for accurate mass and age determinations and to confirm their membership in the halo.
- ID:
- ivo://CDS.VizieR/J/MNRAS/353/601
- Title:
- 2dF survey of the Small Magellanic Cloud
- Short Name:
- J/MNRAS/353/601
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a catalogue of new spectral types for hot, luminous stars in the Small Magellanic Cloud. The catalogue contains 4161 objects, giving an order of magnitude increase in the number of SMC stars with published spectroscopic classifications. The targets are primarily B- and A-type stars (2862 and 853 objects respectively), with 1 Wolf-Rayet, 139 O-type, and 306 FG stars, sampling the main sequence to ~mid-B. The selection and classification criteria are described, and objects of particular interest are discussed, including UV-selected targets from the Ultraviolet Imaging Telescope (UIT) experiment, Be and B[e] stars, `anomalous A supergiants', and composite-spectrum systems. We examine the incidence of Balmer-line emission, and the relationship between H-gamma equivalent width and absolute magnitude for BA stars.
- ID:
- ivo://CDS.VizieR/J/AJ/121/2032
- Title:
- Direct variables in M33A field
- Short Name:
- J/AJ/121/2032
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- DIRECT is a project to directly obtain the distances to two Local Group galaxies, M31 and M33, which occupy a crucial position near the bottom of the cosmological distance ladder. As the first step of the DIRECT project, we have searched for detached eclipsing binaries (DEBs) and new Cepheids in the M31 and M33 galaxies with 1 m class telescopes. In this paper, we present a catalog of variable stars discovered in the data from the follow-up observations of the DEB system D33J013346.2+304439.9 in field M33A (RA=23.55{deg}, DE=30.72{deg}; J2000.0), collected with the Kitt Peak National Observatory's 2.1 m telescope. In our search covering an area of 108arcmin^2^, we have found 434 variable stars: 63 eclipsing binaries, 305 Cepheids, and 66 other periodic, possible long-period, or nonperiodic variables. Of these variables, 280 are newly discovered, mainly short-period and/or faint Cepheids. Their light curves were extracted using the ISIS image subtraction package. For 85% of the variables, we present light curves in standard V and B magnitudes, with the remaining 15% expressed in units of differential flux. We have discovered a population of first-overtone Cepheid candidates, and for eight of them we present strong arguments in favor of this interpretation. We also report on the detection of a nonlinearity in the KPNO T2KA and T1KA cameras.
- ID:
- ivo://CDS.VizieR/J/AJ/122/2477
- Title:
- DIRECT variables in M33B field
- Short Name:
- J/AJ/122/2477
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- DIRECT is a project to obtain directly the distances to two Local Group galaxies, M31 and M33, which occupy a crucial position near the bottom of the cosmological distance ladder. As the first step of the DIRECT project we have searched for detached eclipsing binaries (DEBs) and new Cepheids in the M31 and M33 galaxies with 1m class telescopes. In this eighth paper we present a catalog of variable stars discovered in the data from the follow-up observations of DEB system D33J013337.0+303032.8 in field M33B [(RA,DE)=(23.48{deg}, 30.57{deg}), J2000.0], collected with the Kitt Peak National Observatory 2.1m telescope. In our search covering an area of 108arcmin^2^ we have found 895 variable stars: 96 eclipsing binaries, 349 Cepheids, and 450 other periodic, possibly long-period or nonperiodic variables. Of these variables 612 are newly discovered. Their light curves were extracted using the ISIS image subtraction package. For 77% of the variables we present light curves in standard V and B magnitudes, with the remaining 23% expressed in units of differential flux. We have discovered a population of first-overtone Cepheid candidates, and for six of them we present strong arguments in favor of this interpretation. The catalog of variables, as well as their photometry (about 9.2x10^4^ BV measurements) and finding charts, is available electronically via anonymous ftp and the World Wide Web. The complete set of the CCD frames is available upon request.
