- 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.
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- 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.
22834. 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.
- ID:
- ivo://CDS.VizieR/J/A+A/591/A115
- Title:
- VISTA-VHS (MOVIS) minor planets NIR photometry
- Short Name:
- J/A+A/591/A115
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The NIR photometric data of minor planets observed by the VISTA-VHS survey. This survey uses Y, J, H, and Ks filters for imaging the entire sky of the southern hemisphere. A total of 39947 Solar System objects were detected in the VISTA VHS Data Release 3. The detections found include: 52 NEAs, 325 Mars Crossers, 515 Hungaria asteroids, 38428 Main Belt asteroids, 146 Cybele asteroid, 147 Hilda asteroids, 270 Trojans, 13 comets, 12 Kuiper Belt objects, and Neptune with its 4 satellites. About 34998 of these objects were imaged with at least two different filters.
- ID:
- ivo://CDS.VizieR/J/MNRAS/436/413
- Title:
- VISTA ZJKs photometry of Sgr dSph
- Short Name:
- J/MNRAS/436/413
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the deepest near-infrared (ZJKs) photometry yet obtained of the Sagittarius dwarf spheroidal (Sgr dSph), using Visible and Infrared Survey Telescope for Astronomy (VISTA) to survey 11 square degrees centred on its core. We list locations and ZJKs-band magnitudes for over 2.9 million sources in the field. We discuss the isolation of the Sgr dSph from the foreground and Galactic Bulge populations, identify the Sgr dSph's horizontal branch in the near-infrared for the first time and map the density of the galaxy's stars. We present isochrones for the Sgr dSph and Bulge populations. These are consistent with the previously reported properties of the Sgr dSph core: namely that it is dominated by a population between [Fe/H]~-1dex and solar, with a significant [{alpha}/Fe] versus [Fe/H] gradient. While strong contamination from the Galactic Bulge prevents accurate measurement of the (Galactic) north side of the Sgr dSph, the dwarf galaxy can be well approximated by a roughly ovaloid projection of characteristic size 4{deg}x2{deg}, beyond which the projected stellar density is less than half that of the region surrounding the core. The galaxy's major axis is perpendicular to the Galactic Plane, as in previous studies. We find slight evidence to confirm a metallicity gradient in the Sgr dSph and use isochrones to fit a distance of 24.3+/-2.3kpc. We were unable to fully constrain the metallicity distribution of the Sgr dSph due to the Bulge contamination and strong correlation of [{alpha}/Fe] with metallicity; however, we find that metal-poor stars ([Fe/H]<~-1) make up <~29% of the Sgr dSph's upper red giant branch population. The Bulge population is best fitted by a younger population with [Fe/H] {approx} 0 and [{alpha}/Fe] {approx} 0 or slightly higher. We find no evidence for a split, peanut- or X-shaped Bulge population in this line of sight (l=5.6+/-~1{deg}, b=-14.1+/-~3{deg}).
- ID:
- ivo://CDS.VizieR/J/AJ/157/171
- Title:
- Visual analysis and demographics of Kepler TTVs
- Short Name:
- J/AJ/157/171
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We visually analyzed the transit timing variation (TTV) data of 5930 Kepler Objects of Interest (KOIs) homogeneously. Using data from Rowe et al. (2014, J/ApJ/784/45) and Holczer et al. (2015, J/ApJ/807/170; 2016, J/ApJS/225/9), we investigated TTVs for nearly all KOIs in Kepler's Data Release 24 catalog. Using TTV plots, periodograms, and phase-folded quadratic plus sinusoid fits, we visually rated each KOI's TTV data in five categories. Our ratings emphasize the hundreds of planets with TTVs that are weaker than the ~200 that have been studied in detail. Our findings are consistent with statistical methods for identifying strong TTVs, though we found some additional systems worth investigation. Between about 3-50 days and 1.3-6 Earth radii, the frequency of strong TTVs increases with period and radius. As expected, strong TTVs are very common when period ratios are near a resonance, but there is not a one-to-one correspondence. The observed planet-by-planet frequency of strong TTVs is only somewhat lower in systems with one or two known planets (7%+/-1%) than in systems with three or more known planets (11%+/-2%). We attribute TTVs to known planets in multitransiting systems but find ~30 cases where the perturbing planet is unknown. Our conclusions are valuable as an ensemble for learning about planetary system architectures and individually as stepping stones toward more-detailed mass-radius constraints. We also discuss Data Release 25 TTVs, investigate ~100 KOIs with transit duration and/or depth variations, and estimate that the Transiting Exoplanet Survey Satellite will likely find only ~10 planets with strong TTVs.
