- ID:
- ivo://CDS.VizieR/J/MNRAS/503/2265
- Title:
- VISTA and Subaru/HSC obs. of Upper Scorpius
- Short Name:
- J/MNRAS/503/2265
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We aim at identifying very low-mass isolated planetary-mass member candidates in the nearest OB association to the Sun, Upper Scorpius (145pc; 5-10Myr), to constrain the form and shape of the luminosity function and mass spectrum in this regime. We conducted a deep multi-band (Y=21.2, J=20.5, Z=22.0mag) photometric survey of six square degrees in the central region of Upper Scorpius. We extend the current sequence of astrometric and spectroscopic members by about two magnitudes in Y and one magnitude in J, reaching potentially T-type free-floating members in the association with predicted masses below 5 Jupiter masses, well into the planetary-mass regime. We extracted a sample of 57 candidates in this area and present infrared spectroscopy confirming two of them as young L-type members with characteristic spectral features of 10Myr-old brown dwarfs. Among the 57 candidates, we highlight 10 new candidates fainter than the coolest members previously confirmed spectroscopically. We do not see any obvious sign of decrease in the mass spectrum of the association, suggesting that star processes can form substellar objects with masses down to 4-5 Jupiter masses.
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Search Results
- ID:
- ivo://CDS.VizieR/III/334
- Title:
- VISTA Deep Extragalactic Observations (VIDEO)
- Short Name:
- III/334
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- VIDEO is a ~12 square degrees survey in the near-infrared Z, Y, J, H and Ks bands,over the ELAIS-S1, XMMLS, and ECDFS extragalactic fields. This document describes the catalog released for the deep stracked data in the VIDEO-XMM3 field, which also covers the Canada-France-Hawaii Telescope Legacy Survey Deep-1 field (CFHTLS-D1).
- ID:
- ivo://CDS.VizieR/J/ApJ/754/30
- Title:
- VISTA IR photometry of {sigma} Ori cluster
- Short Name:
- J/ApJ/754/30
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report on our analysis of the VISTA Orion ZY JHK_s_ photometric data (completeness magnitudes of Z=22.6 and J=21.0 mag) focusing on a circular area of 2798.4arcmin^2^ around the young {sigma} Orionis star cluster (~3Myr, ~352pc, and solar metallicity). The combination of the VISTA photometry with optical, WISE and Spitzer data allows us to identify a total of 210 {sigma} Orionis member candidates with masses in the interval 0.25-0.004M_{sun}_, 23 of which are new planetary-mass object findings. These discoveries double the number of cluster planetary-mass candidates known so far. One object has colors compatible with a T spectral type. The {sigma} Orionis cluster harbors about as many brown dwarfs (69, 0.072-0.012M_{sun}_) and planetary-mass objects (37, 0.012-0.004M_{sun}_) as very low mass stars (104, 0.25-0.072M_{sun}_). Based on Spitzer data, we derive a disk frequency of ~40% for very low mass stars, brown dwarfs, and planetary-mass objects in {sigma} Orionis. The radial density distributions of these three mass intervals are alike: all are spatially concentrated within an effective radius of 12' (1.2pc) around the multiple star {sigma} Ori, and no obvious segregation between disk-bearing and diskless objects is observed.
- ID:
- ivo://CDS.VizieR/J/ApJ/810/L20
- Title:
- VISTA KS photometry of EWS 2012-BLG-548
- Short Name:
- J/ApJ/810/L20
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report the discovery of a large timescale candidate microlensing event of a bulge stellar source based on near-infrared observations with the VISTA Variables in the Via Lactea Survey (VVV). The new microlensing event is projected only 3.5 arcmin away from the center of the globular cluster NGC 6553. The source appears to be a bulge giant star with magnitude K_s_=13.52, based on the position in the color-magnitude diagram. The foreground lens may be located in the globular cluster, which has well-known parameters such as distance and proper motions. If the lens is a cluster member, we can directly estimate its mass simply following Paczynski which is a modified version of the more general case due to Refsdal. In that case, the lens would be a massive stellar remnant, with M=1.5-3.5M_{sun}_. If the blending fraction of the microlensing event appears to be small, and this lens would represent a good isolated black hole (BH) candidate, that would be the oldest BH known. Alternative explanations (with a larger blending fraction) also point to a massive stellar remnant if the lens is located in the Galactic disk and does not belong to the globular cluster.
- ID:
- ivo://CDS.VizieR/J/MNRAS/424/1807
- Title:
- VISTA Magellanic Cloud Survey. V. Cepheids
- Short Name:
- J/MNRAS/424/1807
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The VISTA Magellanic Cloud (VMC; PI: M.-R. L. Cioni) survey is collecting deep K_s_-band time series photometry of the pulsating variable stars hosted by the system formed by the two Magellanic Clouds (MCs) and the bridge connecting them. In this paper, we present the first results for classical Cepheids, from the VMC observations of two fields in the Large Magellanic Cloud (LMC), centred on the South Ecliptic Pole and the 30 Doradus star-forming regions, respectively. The VMC K_s_-band light curves of the Cepheids are well sampled (12 epochs) and of excellent precision (typical errors of ~0.01mag). We were able to measure for the first time the K_s_magnitude of the faintest classical Cepheids in the LMC (K_s_~17.5mag), which are mostly pulsating in the first overtone (FO) mode, and to obtain FO period--luminosity (PL), period-Wesenheit (PW) and period-luminosity-colour (PLC) relations, spanning the full period range from 0.25 to 6d. Since the longest period Cepheid in our data set has a variability period of 23d, we have complemented our sample with literature data for brighter F Cepheids. On this basis, we have built a PL relation in the K_s_ band that, for the first time, includes short-period - hence low-luminosity - pulsators, and spans the full range from 1.6 to 100 d in period.We also provide the first ever empirical PW and PLC relations using the (V-K_s_) colour and time series K_s_photometry. The very small dispersion (~0.07mag) of these relations makes them very well suited to study the three-dimensional geometry of the Magellanic system. The use of 'direct' (parallax- and Baade--Wesselink-based) distance measurements to both Galactic and LMC Cepheids allowed us to calibrate the zero-points of the PL, PW and PLC relations obtained in this paper, and in turn to estimate an absolute distance modulus of (m-M)_0_=18.46+/-0.03mag for the LMC. This result is in agreement with most of the latest literature determinations based on classical Cepheids.
- ID:
- ivo://CDS.VizieR/II/351
- Title:
- VISTA Magellanic Survey (VMC) catalog
- Short Name:
- II/351
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The new VISual and Infrared Telescope for Astronomy (VISTA) has started operations in 2009. Over its first five years it collected data for six public surveys, one of which is the near-infrared YJKs VISTA survey of the Magellanic Clouds system (VMC). This survey comprises the Large Magellanic Cloud (LMC), the Small Magellanic Cloud, the Magellanic Bridge connecting the two galaxies and two fields in the Magellanic Stream. The main goals of the VMC survey are the determination of the spatially-resolved star-formation history and the three-dimensional structure of the Magellanic system. The VMC survey is therefore designed to reach stars as faint as the oldest main sequence turn-off point and to constrain the mean magnitude of pulsating variables such as RR Lyrae stars and Cepheids. The VMC data are comprised of multi-epoch observations which are executed following specific time constraints. The first science results, aimed at assessing the scientific quality of the VMC data, include an overview of the distribution of stars in colour-magnitude and colour-colour diagrams, the detection of planetary nebulae and stellar clusters, and the Ks band light-curves of variable stars. The VMC survey represents a tremendous improvement, in spatial resolution and sensitivity, on previous panoramic observations of the Magellanic system in the near-infrared, providing a powerful complement to deep observations at other wavelengths.
20917. VISTA Orion mini-survey
- ID:
- ivo://CDS.VizieR/J/A+A/581/A140
- Title:
- VISTA Orion mini-survey
- Short Name:
- J/A+A/581/A140
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Orion cloud complex presents a variety of star formation mechanisms and properties and is still one of the most intriguing targets for star formation studies. We present VISTA/VIRCAM near-infrared observations of the L1630N star-forming region, including the stellar clusters NGC 2068 and NGC 2071 in the Orion molecular cloud B, and discuss them in combination with Spitzer data. We select 186 young stellar object (YSO) candidates in the region on the basis of multi-color criteria, confirm the YSO nature of the majority of them using published spectroscopy from the literature, and use this sample to investigate the overall star formation properties in L1630N. The K-band luminosity function of L1630N is remarkably similar to that of the Trapezium cluster, i.e., it presents a broad peak in the range 0.3-0.7M_{sun}_ and a fraction of substellar objects of ~20%. The fraction of YSOs still surrounded by disk/envelopes is very high (~85%) compared to other star-forming regions of similar age (1-2Myr), but includes some uncertain corrections for diskless YSOs. Yet, a possibly high disk fraction, together with the fact that 1/3 of the cloud mass has a gas surface density above the threshold for star formation (~129M_{sun}_/pc^2^), points toward a still ongoing star formation activity in L1630N. The star formation efficiency (SFE), star formation rate (SFR), and density of star formation of L1630N are within the ranges estimated for Galactic star-forming regions by the Spitzer "core to disk" and "Gould's Belt" surveys. However, the SFE and SFR are lower than the average value measured in the Orion A cloud and, in particular, lower than that in the southern regions of L1630. This might suggest different star formation mechanisms within the L1630 cloud complex.
- ID:
- ivo://CDS.VizieR/II/348
- Title:
- VISTA Variable in the Via Lactea Survey DR2
- Short Name:
- II/348
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The VVV Survey data delivered in this part of ESO Data Release 2 (DR2) are based on the VISTA/VIRCAM images that were acquired up to September 30, 2011, and processed by the Cambridge Astronomical Survey Unit (CASU). This "VVV_CAT" data release contains the single-epoch band-merged (Z, Y, J, H, Ks) catalogues associated with the VVV tile images that have already been released in the part of DR2 identified as Batch 2 of the "VVV' collection in the ESO archive. VVV_CAT contains 348 tile catalogues.
- ID:
- ivo://CDS.VizieR/J/MNRAS/439/2618
- Title:
- VISTA variables in Sagittarius dSph
- Short Name:
- J/MNRAS/439/2618
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Variability is examined in over 2.6 million stars covering 11 square degrees of the core of the Sagittarius dwarf spheroidal galaxy (Sgr dSph) from Visible and Infrared Survey Telescope for Astronomy Z-band observations. Generally, pulsation on the Sgr dSph giant branches appears to be excited by the internal {kappa} mechanism. Pulsation amplitudes appear identical between red and asymptotic (red giant branch/asymptotic giant branch) giant stars, and between unreddened carbon and oxygen-rich stars at the same luminosity. The lack of correlation between infrared excess and variability among oxygen-rich stars indicates that pulsations do not contribute significantly to wind driving in oxygen-rich stars in the Sgr dSph, though the low amplitudes of these stars mean this may not apply elsewhere. The dust-enshrouded carbon stars have the highest amplitudes of the stars we observe. Only in these stars does an external {kappa}-mechanism-driven pulsation seem likely, caused by variations in their more opaque carbon-rich molecules or dust. This may allow pulsation driving of winds to be effective in carbon stars. Variability can be simplified to a power law (A{prop.to}L/T_2_), as in other systems. In total, we identify 3026 variable stars (with rms variability of {delta}Z>~0.015mag), of which 176 are long-period variables associable with the upper giant branches of the Sgr dSph. We also identify 324 candidate RR Lyrae variables in the Sgr dSph and 340 in the outer Galactic bulge.
- ID:
- ivo://CDS.VizieR/II/337
- Title:
- VISTA Variables in the Via Lactea Survey DR1
- Short Name:
- II/337
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The VVV survey targets the galactic bulge and a piece of the adjacent plane in Z, Y, J, H, and Ks. The total area of this survey is 520 square degrees and contains 355 open and 33 globular clusters. The VVV is multi-epoch in nature in order to detect a large number of variable objects and will provide > 100 carefully spaced observations for each tile. 5-sigma detection limits are Z=21.9, Y=21.2, J=20.2, H=18.2, Ks=18.1. These will be used to create a 3-dimensional map of the Bulge from well-understood distance indicators such as RR Lyrae stars. Other science drivers include the ages of stellar populations, globular cluster evolution, as well as the stellar initial mass function. The VVV Survey data delivered in this part of ESO Data Release 1 (DR1) includes the VISTA/VIRCAM paw-print and tile images that were acquired until September 30, 2010, and processed by the Cambridge Astronomical Survey Unit (CASU). This VVV_CAT data release contains the single-epoch band-merged (Z,Y,J,H,Ks) catalogues associated with the VVV tile images that have already been released in the part of DR1 identified as VVV in the ESO archive. VVV_CAT contains 269 tile catalogues.
