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4631. V1184 Tauri UBVRI light curves
ID:
ivo://CDS.VizieR/J/A+A/582/A113
Title:
V1184 Tauri UBVRI light curves
Short Name:
J/A+A/582/A113
Date:
21 Oct 2021
Publisher:
CDS
Description:
V1184 Tau (CB 34V) lies in the field of the Bok globule CB 34 and was discovered as a large amplitude variable in 1993. According to the first hypothesis of the variability of the star, it is a FU Orionis candidate erupted between 1951 and 1993. During subsequent observations, the star manifests large amplitude variability interpreted as obscuration from circumstellar clouds of dust. We included V1184 Tau (CB 34V) in our target list of highly variable pre-main-sequence stars to determine the reasons for the variations in the brightness of this object. Data from BVRI photometric observations of V1184 Tau were performed in two observatories with two medium-sized and two small telescopes. Our results indicate that during periods of maximum light the star shows characteristics typical of T Tauri stars. During the observed deep minimum in brightness, however, V1184 Tau is rather similar to UX Orionis objects. The deep drop in brightness magnitude diagrams is also confirmation of obscuration from circumstellar clouds of dust as a reason for the large amplitude variability in the brightness.
4632. V471 Tau system: RVs and BVRI LCs
ID:
ivo://CDS.VizieR/J/ApJ/810/157
Title:
V471 Tau system: RVs and BVRI LCs
Short Name:
J/ApJ/810/157
Date:
21 Oct 2021
Publisher:
CDS
Description:
V471 Tauri, a white dwarf-red dwarf eclipsing binary (EB) in the Hyades, is well known for stimulating development of common envelope theory, whereby novae and other cataclysmic variables form from much wider binaries by catastrophic orbit shrinkage. Our evaluation of a recent imaging search that reported negative results for a much postulated third body shows that the object could have escaped detection or may have actually been seen. The balance of evidence continues to favor a brown dwarf companion about 12 AU from the EB. A recently developed algorithm finds unified solutions from three data types. New radial velocities (RVs) of the red dwarf and BVRcIc light curves are solved simultaneously along with white dwarf and red dwarf RVs from the literature, uvby data, the Microvariability and Oscillations of Stars mission light curve, and 40 years of eclipse timings. Precision-based weighting is the key to proper information balance among the various data sets. Timewise variation of modeled starspots allows unified solution of multiple data eras. Light-curve amplitudes strongly suggest decreasing spottedness from 1976 to about 1980, followed by approximately constant spot coverage from 1981 to 2005. An explanation is proposed for lack of noticeable variation in 1981 light curves, in terms of competition between spot and tidal variations. Photometric-spectroscopic distance is estimated. The red dwarf mass comes out larger than normal for a K2 V star, and even larger than adopted in several structure and evolution papers. An identified cause for this result is that much improved red dwarf RV curves now exist.
4633. V830 Tau VI light curves and RV curves
ID:
ivo://CDS.VizieR/J/A+A/642/A133
Title:
V830 Tau VI light curves and RV curves
Short Name:
J/A+A/642/A133
Date:
21 Oct 2021
Publisher:
CDS
Description:
Detecting and characterising exoworlds around very young stars (age<=10Myr) are key aspects of exoplanet demographic studies, especially for understanding the mechanisms and timescales of planet formation and migration. Any reliable theory for such physical phenomena requires a robust observational database to be tested. However, detection using the radial velocity method alone can be very challenging because the amplitude of the signals caused by the magnetic activity of such stars can be orders of magnitude larger than those induced even by massive planets. We observed the very young (~2Myr) and very active star V830 Tau with the HARPS-N spectrograph between October 2017 and March 2020 to independently confirm and characterise the previously reported hot Jupiter V830 Tau b (K_b_=68+/-11ms; m_b_sini_b_=0.57+/-0.10M_jup_; P_b_=4.927+/-0.008d). Because of the observed ~1km/s radial velocity scatter that can clearly be attributed to the magnetic activity of V830 Tau, we analysed radial velocities extracted with different pipelines and modelled them using several state-of-the-art tools. We devised injection-recovery simulations to support our results and characterise our detection limits. The analysis of the radial velocities was aided by a characterisation of the stellar activity using simultaneous photometric and spectroscopic diagnostics. Despite the high quality of our HARPS-N data and the diversity of tests we performed, we were unable to detect the planet V830 Tau b in our data and cannot confirm its existence. Our simulations show that a statistically significant detection of the claimed planetary Doppler signal is very challenging. It is important to continue Doppler searches for planets around young stars, but utmost care must be taken in the attempt to overcome the technical difficulties to be faced in order to achieve their detection and characterisation. This point must be kept in mind when assessing their occurrence rate, formation mechanisms, and migration pathways, especially without evidence of their existence from photometric transits.
4634. V1794 UBVR time series
ID:
ivo://CDS.VizieR/J/A+A/351/212
Title:
V1794 UBVR time series
Short Name:
J/A+A/351/212
Date:
21 Oct 2021
Publisher:
CDS
Description:
Standard Johnson UBVRI photometry of V1794 Cyg (HD 199178) between 1975 and 1995 is analysed. Instead of the traditional constant period ephemeris, we determine the seasonal periodicities (P_phot_) and the primary and secondary minima epochs (t_min,1_, t_min,2_) of the normalized UBVRI magnitudes using the three stage period analysis (TSPA) and complementary methods.
4635. VUDS Dicovery of a high-redshift protocluster
ID:
ivo://CDS.VizieR/J/A+A/572/A41
Title:
VUDS Dicovery of a high-redshift protocluster
Short Name:
J/A+A/572/A41
Date:
21 Oct 2021
Publisher:
CDS
Description:
Using new spectroscopic observations obtained as part of the VIMOS Ultra-Deep Survey (VUDS), we performed a systematic search for overdense environments in the early universe (z>2) and report here on the discovery of Cl J0227-0421, a massive protocluster at z=3.29. This protocluster is characterized by both the large overdensity of spectroscopically confirmed members, delta_gal=10.5+/-2.8, and a significant overdensity in photometric redshift members. The halo mass of this protocluster is estimated by a variety of methods to be ~3x10^14^M_{sun}_ at z~3.3, which, evolved to z=0 results in a halo mass rivaling or exceeding that of the Coma cluster. The properties of 19 spectroscopically confirmed member galaxies are compared with a large sample of VUDS/VVDS galaxies in lower density field environments at similar redshifts. We find tentative evidence for an excess of redder, brighter, and more massive galaxies within the confines of the protocluster relative to the field population, which suggests that we may be observing the beginning of environmentally induced quenching. The properties of these galaxies are investigated, including a discussion of the brightest protocluster galaxy, which appears to be undergoing vigorous coeval nuclear and starburst activity. The remaining member galaxies appear to have characteristics that are largely similar to the field population. Though we find weaker evidence of the suppression of the median star formation rates among and differences in the stacked spectra of member galaxies with respect to the field, we defer any conclusions about these trends to future work with the ensemble of protostructures that are found in the full VUDS sample.
4636. VVV and DECaPS photometry of the GC Minni 22
ID:
ivo://CDS.VizieR/J/ApJ/866/12
Title:
VVV and DECaPS photometry of the GC Minni 22
Short Name:
J/ApJ/866/12
Date:
21 Oct 2021
Publisher:
CDS
Description:
We use deep near-IR photometry of the VISTA Variables in the Via Lactea (VVV) Survey and deep DECam Plane Survey (DECaPS) optical photometry to confirm the physical reality of the candidate globular cluster (GC) Minni 22, which is located in the Galactic bulge. This object, which was detected as a high density region in our maps of bulge red giants, is now confirmed as a real GC based on the optical and near-IR color-magnitude diagrams. We also recover three known fundamental mode (ab type) RR Lyrae stars within 2 arcmin of the cluster center. The presence of RR Lyrae stars also seems to confirm Minni 22 as a bonafide old and metal-poor GC. We estimate a cluster reddening E(J-Ks)=0.6mag and determine its heliocentric distance D=7.4+/-0.3kpc. The optical and near-IR color-magnitude diagrams reveal well-defined red giant branches in all cases, including a red giant branch bump at Ks=13.30+/-0.05mag. The comparison with theoretical isochrones yields a mean metallicity of [Fe/H]=-1.3+/-0.3dex, and age of t~11.2Gyr. This is a good example of a new low-luminosity (M_V_=-6.2mag) GC found in the central bulge of the Milky Way. After discussing the different ways to confirm the existence of bulge GC candidates, we find that one of the best methods is to use the CMDs from the combination of the DECaPS+VVV photometries.
4637. VVV high proper motion stars. I. Ks<=13.5 stars
ID:
ivo://CDS.VizieR/J/MNRAS/464/1247
Title:
VVV high proper motion stars. I. Ks<=13.5 stars
Short Name:
J/MNRAS/464/1247
Date:
21 Oct 2021
Publisher:
CDS
Description:
Knowledge of the stellar content near the Sun is important for a broad range of topics ranging from the search for planets to the study of Milky Way (MW) structure. The most powerful method for identifying potentially nearby stars is proper motion (PM) surveys. All old optical surveys avoid, or are at least substantially incomplete, near the Galactic plane. The depth and breadth of the 'VISTA Variables in Via Lactea' (VVV) near-IR survey significantly improves this situation. Taking advantage of the VVV survey data base, we have measured PMs in the densest regions of the MW bulge and southern plane in order to complete the census of nearby objects. We have developed a custom PM pipeline based on VVV catalogues from the Cambridge Astronomy Survey Unit, by comparing the first epoch of JHKs with the multi-epoch Ks bands acquired later. Taking advantage of the large time baseline between the Two Micron All Sky Survey (2MASS) and the VVV observations, we also obtained 2MASS-VVV PMs. We present a near-IR PM catalogue for the whole area of the VVV survey, which includes 3003 moving stellar sources. All of these have been visually inspected and are real PM objects. Our catalogue is in very good agreement with the PM data supplied in IR catalogues outside the densest zone of the MW. The majority of the PM objects in our catalogue are nearby M-dwarfs, as expected. This new data base allows us to identify 57 common PM binary candidates, among which are two new systems within 30 pcof the Sun.
4638. VV Vir BVRI differential photometry
ID:
ivo://CDS.VizieR/J/AJ/136/1667
Title:
VV Vir BVRI differential photometry
Short Name:
J/AJ/136/1667
Date:
21 Oct 2021
Publisher:
CDS
Description:
VV Vir is a near-contact but detached mid-G-type eclipsing binary with an asymmetrical light curve due to a weak but regular mass exchange. The binary is apparently approaching contact and has a stream impact spot on the secondary component that is responsible for a quadratically [dP/P=(-7.8+/-0.2)x10^-11^] decreasing period. Our period study included more than 140 minima observed over the past 60 years. We explore other possible near-contact configurations for this binary.
4639. VY Scl reduced spectra & radial velocities
ID:
ivo://CDS.VizieR/J/A+A/617/A16
Title:
VY Scl reduced spectra & radial velocities
Short Name:
J/A+A/617/A16
Date:
21 Oct 2021
Publisher:
CDS
Description:
In the context of a large campaign to determine the system parameters of high mass transfer cataclysmic variables, we found VY Scl in a low state in 2008. Making use of this low state, we study the stellar components of the binary with little influence of the normally dominating accretion disc. Time-resolved spectroscopy and photometry of VY Scl taken during the low state are presented. We analysed the light-curve and radial velocity curve and use time-resolved spectroscopy to calculate Doppler maps of the dominant emission lines. The spectra show narrow emission lines of Halpha, Hbeta, HeI, NaI D, and FeII, as well as faint TiO absorption bands that trace the motion of the irradiated secondary star, and Halpha and HeI emission line wings that trace the motion of the white dwarf. From these radial velocities, we find an orbital period of 3.84h, and put constraints on binary parameters such as the mass ratio M2/M1 of 0.43 and the inclination of 15. With a secondary mass between 0.3 and 0.35M_{sun}_, we derive the mass for the white dwarf as M1=0.6-1.1M_{sun}_.
4640. Walraven photometry in Sco-Cen association
ID:
ivo://CDS.VizieR/J/A+A/216/44
Title:
Walraven photometry in Sco-Cen association
Short Name:
J/A+A/216/44
Date:
21 Oct 2021
Publisher:
CDS
Description:
Walraven photometry is presented of established and probable members of the Scorpio-Centaurus OB association. For each star, effective temperature and surface gravity are derived using Kurucz atmosphere models (1979ApJS...40....1K). From the Straizys and Kuriliene (1981Ap&SS..80..353S) tables, absolute magnitudes are calculated. Distance moduli and visual extinctions are determined for all stars. From a comparison of the HR-diagrams of the stars in each subgroup with theoretical isochrones, the ages of the three subgroups are derived. The distances to the three subgroups are shown to be different; there is a general trend (also within each subgroup) for the distances to be larger at higher galactic longitudes. The visual extinction in the youngest subgroup Upper-Scorpius, is well correlated with the IRAS 100-micron map. The distance toward the Ophiuchus dark clouds is found to be 125 pc, based on the photometric distances to the stars. Most of the early-type stars in Upper-Scorpius are located at the far side of the dark clouds.