- ID:
- ivo://CDS.VizieR/J/A+A/573/A126
- Title:
- VLT/NaCo Large program I. Sample
- Short Name:
- J/A+A/573/A126
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Young, close stars are ideal targets for searching planets using the direct imaging technique. The determination of stellar parameters is crucial for the interpretation of imaging survey results, particularly since the luminosity of substellar objects has a strong dependence on system age. We have conducted a large program with NaCo at the VLT to search for planets and brown dwarfs in wide orbits around 86 stars. A large fraction of the targets observed with NaCo were poorly investigated in the literature. We performed a study to characterize the fundamental properties (age, distance, and mass) of the stars in our sample. To improve target age determinations, we compiled and analyzed a complete set of age diagnostics. We measured spectroscopic parameters and age diagnostics using dedicated observations acquired with FEROS and CORALIE spectrographs at La Silla Observatory. We also made extensive use of archival spectroscopic data and the results that are available in the literature. Additionally, we exploited photometric time-series, which are available in ASAS and Super-WASP archives, to derive a rotational period for a large fraction of our program stars. We provided updated characterization of all the targets observed in the VLT NaCo Large program, a survey designed to probe the occurrence of exoplanets and brown dwarfs in wide orbits. The median distance and age of our program stars are 64pc and 100Myr, respectively. Nearly all the stars have masses between 0.70 and 1.50M_{sun}_, with a median value of 1.01M_{sun}_. The typical metallicity is close to solar with a dispersion that is smaller than that of samples usually observed in radial velocity surveys. Several stars are confirmed or proposed here to be members of close young moving groups. Eight spectroscopic binaries are identified.
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Search Results
- ID:
- ivo://CDS.VizieR/J/AJ/153/115
- Title:
- VLT/SINFONI observations of MIPSGAL "bubbles"
- Short Name:
- J/AJ/153/115
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present Very Large Telescope/Spectrograph for INtegral Field Observations in the Near Infrared H- and K-band spectra of potential central stars within the inner 8"-by-8" regions of 55 MIPSGAL "bubbles" (MBs), sub-arcminute circumstellar shells discovered in the mid-IR survey of the Galactic plane with Spitzer/MIPS. At magnitudes brighter than 15, we detect a total of 230 stars in the K band and 179 stars in the H band. We spectrally identify 145 stars in all but three MBs, with average magnitudes of 13.8 and 12.7 respectively, using spectral libraries and previous studies of near-IR stellar spectra. We also use tabulated intrinsic stellar magnitudes and colors to derive distances and extinction values, and to better constrain the classifications of the stars. We reliably identify the central sources for 21 of the 55 MBs, which we classify as follows: one Wolf-Rayet, three luminous blue variable candidates, four early-type (O to F), and 15 late-type (G to M) stars. The 21 central sources are, on average, one magnitude fainter than these in the most recent study of MBs, and we notice a significant drop in the fraction of massive star candidates. For the 34 remaining MBs in our sample, we are unable to identify the central sources due to confusion, low spectroscopic signal-to-noise ratio, and/or lack of detections in the images near the centers of the bubbles. We discuss how our findings compare with previous studies and support the trend, for the most part, between the shells' morphologies in the mid-IR and central sources spectral types.
- ID:
- ivo://CDS.VizieR/J/A+A/485/41
- Title:
- VLT spectroscopy of blue massive stars in NGC55
- Short Name:
- J/A+A/485/41
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This is the first paper of a series devoted to studying the population of blue massive stars in NGC 55, a galaxy of the Sculptor group at a distance of about 2Mpc. We have obtained optical (3300-6210{AA}), low-resolution spectra of approximately 200 blue massive stars with VLT-FORS2, which we have classified with the aid of Milky Way and Magellanic Cloud standard stars.
- ID:
- ivo://CDS.VizieR/II/350
- Title:
- VLT Survey Telescope ATLAS
- Short Name:
- II/350
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The VLT Survey Telescope ATLAS survey is an optical ugriz survey aiming to cover ~4700deg^2^ of the southern sky to similar depths as the Sloan Digital Sky Survey (SDSS). From reduced images and object catalogues provided by the Cambridge Astronomical Surveys Unit, we first find that the median seeing ranges from 0.8-arcsec FWHM (full width at half-maximum) in i to 1.0-arcsec in u, significantly better than the 1.2-1.5arcsec seeing for SDSS. The 5{sigma} mag limit for stellar sources is r_AB_=22.7 and in all bands these limits are at least as faint as SDSS. SDSS and ATLAS are more equivalent for galaxy photometry except in the z band where ATLAS has significantly higher throughput. We have improved the original ESO magnitude zero-points by comparing m<16 star magnitudes with the AAVSO Photometric All-Sky Survey in gri, also extrapolating into u and z, resulting in zero-points accurate to ~+/-0.02mag. We finally compare star and galaxy number counts in a 250deg^2^ area with SDSS and other count data and find good agreement. ATLAS data products can be retrieved from the ESO Science Archive, while support for survey science analyses is provided by the OmegaCAM Science Archive, operated by the Wide-Field Astronomy Unit in Edinburgh.
- ID:
- ivo://CDS.VizieR/J/A+A/512/A12
- Title:
- VLT/VIMOS spectroscopy in GOODS-South field
- Short Name:
- J/A+A/512/A12
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the full data set of the VIsible Multi-Object Spectrograph (VIMOS) spectroscopic campaign of the ESO/GOODS program in the Chandra Deep Field South (CDFS), which complements the FORS2 ESO/GOODS spectroscopic campaign. The ESO/GOODS spectroscopic programs are aimed at reaching signal-to-noise ratios adequate to measure redshifts for galaxies with AB magnitudes in the range ~24-25 in the B and R band using VIMOS, and in the z band using FORS2.
7966. VMC survey. XVI.
- ID:
- ivo://CDS.VizieR/J/MNRAS/454/839
- Title:
- VMC survey. XVI.
- Short Name:
- J/MNRAS/454/839
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present results based on YJKs photometry of star clusters in the Large Magellanic Cloud (LMC), distributed throughout the central part of the galaxy's bar and the 30 Doradus region. We analysed the field-star-decontaminated colour-magnitude diagrams of 313 clusters to estimate their reddening values and ages. The clusters are affected by a mean reddening of E(B-V){in}[0.2, 0.3]mag, where the average internal LMC reddening amounts to ~0.1-0.2mag. The region covering 30 Doradus includes clusters with reddening values in excess of E(B-V)=0.4mag. Our cluster sample spans the age range 7.0<=log(t/yr)<9.0, represents an increase of 30 percent in terms of the number of clusters with robust age estimates and comprises a statistically complete sample in the LMC regions of interest here. The resulting cluster frequencies suggest that the outermost regions of the LMC bar first experienced enhanced cluster formation - log(t/yr){in}[8.5, 9.0] - before the activity proceeded, although in a patchy manner, to the innermost regions, for log(t/yr)<7.7. Cluster frequencies in the 30 Doradus region show that the area is dominated by very recent cluster formation. The derived star formation frequencies suggest that the cluster and field-star populations do not seem to have fully evolved as fully coupled systems during the last ~100Myr.
- ID:
- ivo://CDS.VizieR/J/MNRAS/473/3131
- Title:
- VMC survey. XXVI. SMC RR Lyrae stars
- Short Name:
- J/MNRAS/473/3131
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present results from the analysis of 2997 fundamental mode RR Lyrae variables located in the Small Magellanic Cloud (SMC). For these objects, near-infrared time series photometry from the VISTA survey of the Magellanic Clouds system (VMC) and visual light curves from the OGLE IV (Optical Gravitational Lensing Experiment IV) survey are available. In this study, the multi-epoch Ks-band VMC photometry was used for the first time to derive intensity-averaged magnitudes of the SMC RR Lyrae stars. We determined individual distances to the RR Lyrae stars from the near-infrared period-absolute magnitude-metallicity (PM_Ks_Z) relation, which has some advantages in comparison with the visual absolute magnitude-metallicity (M_V_-[Fe/H]) relation, such as a smaller dependence of the luminosity on interstellar extinction, evolutionary effects and metallicity. The distances we have obtained were used to study the three-dimensional structure of the SMC. The distribution of the SMC RR Lyrae stars is found to be ellipsoidal. The actual line-of-sight depth of the SMC is in the range 1-10kpc, with an average depth of 4.3+/-1.0kpc. We found that RR Lyrae stars in the eastern part of the SMC are affected by interactions of the Magellanic Clouds. However, we do not see a clear bimodality observed for red clump stars, in the distribution of RR Lyrae stars.
- ID:
- ivo://CDS.VizieR/J/MNRAS/494/458
- Title:
- VMC XXXVI. Young stellar variability in LMC
- Short Name:
- J/MNRAS/494/458
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Studies of young stellar objects (YSOs) in the Galaxy have found that a significant fraction exhibits photometric variability. However, no systematic investigation has been conducted on the variability of extragalactic YSOs. Here we present the first variability study of massive YSOs in an ~1.5 square degree region of the Large Magellanic Cloud (LMC). The aim is to investigate whether the different environmental conditions in the metal-poor LMC (~0.4-0.5Z_{sun}_) have an impact on the variability characteristics. Multi-epoch near-infrared (NIR) photometry was obtained from the VISTA Survey of the Magellanic Clouds (VMC) and our own monitoring campaign using the VISTA telescope. By applying a reduced {Chi}-square-analysis, stellar variability was identified. We found 3062 candidate variable stars from a population of 362425 stars detected. Based on several Spitzer studies, we compiled a sample of high-reliability massive YSOs: a total of 173 massive YSOs have NIR counterparts (down to Ks~18.5mag) in the VMC catalogue, of which 39 display significant (>3{sigma}) variability. They have been classified as eruptive, fader, dipper, short-term variable, and long-period variable YSOs based mostly on the appearance of their Ks-band light curves. The majority of YSOs are aperiodic; only five YSOs exhibit periodic light curves. The observed amplitudes are comparable or smaller than those for Galactic YSOs (only two Magellanic YSOs exhibit {Delta}Ks>1mag), not what would have been expected from the typically larger mass accretion rates observed in the Magellanic Clouds.
- ID:
- ivo://CDS.VizieR/J/AJ/141/44
- Title:
- V396 Mon BVRI light curves
- Short Name:
- J/AJ/141/44
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This paper analyzes the first obtained four-color light curves of V396 Mon using the 2003 version of the W-D code. It is confirmed that V396 Mon is a shallow W-type contact binary system with a mass ratio q=2.554(+/-0.004) and a degree of contact factor f=18.9%(+/-1.2%). A period investigation based on all available data shows that the period of the system includes a long-term decrease (dP/dt=-8.57x10^-8^days/yr) and an oscillation (A3=0.0160day, T3=42.4yr). They are caused by angular momentum loss and light-time effect, respectively. The suspect third body is possibly a small M-type star (about 0.31 solar mass).
7970. V960 Mon light curves
- ID:
- ivo://CDS.VizieR/J/A+A/582/L12
- Title:
- V960 Mon light curves
- Short Name:
- J/A+A/582/L12
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We monitored the recent FUor 2MASS J06593158-0405277 (V960 Mon) since November 2009 at various observatories and multiple wavelengths. After the outburst by nearly 2.9mag in r around September 2014 the brightness gently fades until April 2015 by nearly 1mag in U and 0.5mag in z. Thereafter the brightness at {lambda}>5000{AA} was constant until June 2015 while the shortest wavelengths (U,B) indicate a new rise, similar to that seen for the FUor V2493 Cyg (HBC722). Our near-infrared (NIR) monitoring between December 2014 and April 2015 shows a smaller outburst amplitude (~2mag) and a smaller (0.2-0.3mag) post-outburst brightness decline. Optical and NIR color-magnitude diagrams indicate that the brightness decline is caused by growing extinction. The post-outburst light curves are modulated by an oscillating color-neutral pattern with a period of about 17 days and an amplitude declining from ~0.08mag in October 2014 to ~0.04mag in May 2015. The properties of the oscillating pattern lead us to suggest the presence of a close binary with eccentric orbit.
