- ID:
- ivo://CDS.VizieR/J/AJ/150/141
- Title:
- UrHip Proper Motion Catalog
- Short Name:
- J/AJ/150/141
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Proper motions are computed and collected in a catalog using the Hipparcos positions (epoch 1991.25) and URAT1 positions (epoch 2012.3 to 2014.6). The goal is to obtain a significant improvement on the proper motion accuracy of single stars in the northern hemisphere, and to identify new astrometric binaries perturbed by orbital motion. For binaries and multiple systems, the longer baseline of Tycho2 (~100yr) makes it more reliable despite its larger formal uncertainties. The resulting proper motions obtained for 67340 stars have a consequent gain in accuracy by a factor of ~3 compared to Hipparcos. Comparison between UrHip and Hipparcos shows that they are reasonably close, but also reveals stars with large discrepant proper motions, a fraction of which are potential binary candidates.
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Search Results
- ID:
- ivo://CDS.VizieR/J/A+A/416/811
- Title:
- V and R CCD photometry of visual binaries
- Short Name:
- J/A+A/416/811
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- 429 CCD measurements of relative positions and magnitude differences in V and R photometric bands for 165 visual double and multiple stars are given. CCD frames were taken at the 1.52m Spanish telescope of the Spanish-German Center of Astronomy at Calar Alto (Almeria, Spain). During the reduction process a "Tepui" function was used as the PSF function.
- ID:
- ivo://CDS.VizieR/J/ApJS/211/9
- Title:
- Variability in UV line emission of F-M stars
- Short Name:
- J/ApJS/211/9
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Variations in stellar flux can potentially overwhelm the photometric signal of a transiting planet. Such variability has not previously been well-characterized in the ultraviolet lines used to probe the inflated atmospheres surrounding hot Jupiters. Therefore, we surveyed 38 F-M stars for intensity variations in four narrow spectroscopic bands: two enclosing strong lines from species known to inhabit hot Jupiter atmospheres, C.II {lambda}{lambda}1334, 1335 and SiIII{lambda}1206; one enclosing SiIV {lambda}{lambda}1393, 1402; and 36.5{AA} of interspersed continuum. For each star/band combination, we generated 60s cadence lightcurves from archival Hubble Space Telescope Cosmic Origins Spectrograph and Space Telescope Imaging Spectrograph time-tagged photon data. Within these lightcurves, we characterized flares and stochastic fluctuations as separate forms of variability. Flares: we used a cross-correlation approach to detect 116 flares. These events occur in the time-series an average of once per 2.5hr, over 50% last 4 minutes or less, and most produce the strongest response in SiIV. If the flare occurred during a transit measurement integrated for 60 minutes, 90/116 would destroy the signal of an Earth, 27/116 Neptune, and 7/116 Jupiter, with the upward bias in flux ranging from 1% to 109% of quiescent levels. Fluctuations: photon noise and underlying stellar fluctuations produce scatter in the quiescent data. We model the stellar fluctuations as Gaussian white noise with standard deviation {sigma}_x_. Maximum likelihood values of {sigma}_x_ range from 1% to 41% for 60s measurements. These values suggest that many cool stars will only permit a transit detection to high confidence in ultraviolet resonance lines if the radius of the occulting disk is >~1R_J_. However, for some M dwarfs this limit can be as low as several R_{oplus}_.
- ID:
- ivo://CDS.VizieR/J/AJ/135/649
- Title:
- Variable stars in a Lupus field
- Short Name:
- J/AJ/135/649
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have conducted a wide-field photometric survey in a single 52'x52' field towards the Lupus Galactic Plane in an effort to detect transiting Hot Jupiter planets. The data set also led to the detection of 494 field variables, all of which are new discoveries. This paper presents an overview of the project, along with the total catalog of variables, which comprises 190 eclipsing binaries (of contact, semi-contact, and detached configurations), 51 miscellaneous pulsators of various types, 237 long-period variables (P>=2d), 11 {delta} Scuti stars, 4 field RR Lyrae (3 disk and 1 halo) and 1 irregular variable. Our survey provides a complete catalog of W UMa eclipsing binaries in the field to V=18.8, which display a Gaussian period distribution of 0.277+/-0.036d.
- ID:
- ivo://CDS.VizieR/J/MNRAS/437/1216
- Title:
- VAST Survey. A-type stars multiplicity
- Short Name:
- J/MNRAS/437/1216
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- With a combination of adaptive optics imaging and a multi-epoch common proper motion search, we have conducted a large volume-limited (D<=75pc) multiplicity survey of A-type stars, sensitive to companions beyond 30AU. The sample for the Volume-limited A-STar (VAST) survey consists of 435 A-type stars: 363 stars were observed with adaptive optics, 228 stars were searched for wide common proper motion companions and 156 stars were measured with both techniques. The projected separation coverage of the VAST survey extends from 30 to 45000AU. A total of 137 stellar companions were resolved, including 64 new detections from the VAST survey, and the companion star fraction, projected separation distribution and mass ratio distribution were measured. The separation distribution forms a log-normal distribution similar to the solar-type binary distribution, but with a peak shifted to a significantly wider value of 387^+132^_-98_AU. Integrating the fit to the distribution over the 30 to 10000AU observed range, the companion star fraction for A-type stars is estimated as 33.8+/-2.6%. The mass ratio distribution of closer (<125AU) binaries is distinct from that of wider systems, with a flat distribution for close systems and a distribution that tends towards smaller mass ratios for wider binaries. Combining this result with previous spectroscopic surveys of A-type stars gives an estimate of the total companion star fraction of 68.9+/-7.0%. The most complete assessment of higher order multiples was estimated from the 156 star subset of the VAST sample with both adaptive optics and common proper motion measurements, combined with a thorough literature search for companions, yielding a lower limit on the frequency of single, binary, triple, quadruple and quintuple A-type star systems of 56.4_-4.0_^+3.8^, 32.1_-3.5_^+3.9^, 9.0_-1.8_^+2.8^, 1.9_-0.6_^+1.8^ and 0.6_-0.2_^+1.4^ percent, respectively.
- ID:
- ivo://CDS.VizieR/J/MNRAS/426/739
- Title:
- Velocities for seven transiting hot Jupiters
- Short Name:
- J/MNRAS/426/739
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present seven new transiting hot Jupiters from the WASP-South survey. The planets are all typical hot Jupiters orbiting stars from F4 to K0 with magnitudes of V=10.3-12.5. The orbital periods are all in the range of 3.9-4.6d, the planetary masses range from 0.4 to 2.3-M_Jup_ and the radii from 1.1 to 1.4R_Jup_. In line with known hot Jupiters, the planetary densities range from Jupiter-like to inflated ({rho}=0.13-1.07{rho}_Jup_). We use the increasing numbers of known hot Jupiters to investigate the distribution of their orbital periods and the 3-4d 'pile-up'.
- ID:
- ivo://CDS.VizieR/J/ApJS/213/34
- Title:
- Velocities of Cygnus OB2 massive binaries
- Short Name:
- J/ApJS/213/34
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We analyze orbital solutions for 48 massive multiple-star systems in the Cygnus OB2 association, 23 of which are newly presented here, to find that the observed distribution of orbital periods is approximately uniform in log P for P<45days, but it is not scale-free. Inflections in the cumulative distribution near 6days, 14days, and 45days suggest key physical scales of =~0.2, =~0.4, and =~1A.U. where yet-to-be-identified phenomena create distinct features. No single power law provides a statistically compelling prescription, but if features are ignored, a power law with exponent {beta}=~-0.22 provides a crude approximation over P=1.4-2000days, as does a piece-wise linear function with a break near 45days. The cumulative period distribution flattens at P>45days, even after correction for completeness, indicating either a lower binary fraction or a shift toward low-mass companions. A high degree of similarity (91% likelihood) between the Cyg OB2 period distribution and that of other surveys suggests that the binary properties at P<~25days are determined by local physics of disk/clump fragmentation and are relatively insensitive to environmental and evolutionary factors. Fully 30% of the unbiased parent sample is a binary with period P<45days. Completeness corrections imply a binary fraction near 55% for P<5000days. The observed distribution of mass ratios 0.2<q<1 is consistent with uniform, while the observed distribution of eccentricities 0.1<e<0.6 is consistent with uniform plus an excess of e=~0 systems. We identify six stars, all supergiants, that exhibit aperiodic velocity variations of ~30km/s attributed to atmospheric fluctuations.
- ID:
- ivo://CDS.VizieR/J/AN/323/139
- Title:
- Velocities of Popother/.II binray stars
- Short Name:
- J/AN/323/139
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Radial velocities for 114 Hipparcos stars, mostly high transverse velocity binaries without previous radial velocity measurement, are published. Measurements are made with the CORAVEL-type radial velocity spectrometer. The accuracy of measurements is better than 1km/s. Two stars, BD+30 2129A and HD 117466AB are found to be radial velocity variables, and three more stars, HD 119515A, HD 131597AB, and HD 153344, are possible radial velocity variables.
- ID:
- ivo://CDS.VizieR/J/A+A/619/A2
- Title:
- Velocity curves of 3 open cluster stars
- Short Name:
- J/A+A/619/A2
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The aim of this work is to search for planets around intermediate-mass stars in open clusters by using data from an extensive survey with more than 15 years of observations. We obtain high-precision radial velocities (RV) with the HARPS spectrograph for a sample of 142 giant stars in 17 open clusters. We fit Keplerian orbits when a significant periodic signal is detected. We also study the variation of stellar activity indicators and line-profile variations to discard stellar-induced signals. We present the discovery of a periodic RV signal compatible with the presence of a planet candidate in the 1.15Gyr open cluster IC4651 orbiting the 2.06M_{sun}_ star No. 9122. If confirmed, the planet candidate would have a minimum mass of 7.2M_J_ and a period of 747 days. However, we also find that the FWHM of the CCF varies with a period close to the RV, casting doubts on the planetary nature of the signal. We also provide refined parameters for the previously discovered planet around NGC2423 No. 3 but show evidence that the BIS of the CCF is correlated with the RV during some of the observing periods. This fact advises us that this might not be a real planet and that the RV variations could be caused by stellar activity and/or pulsations. Finally, we show that the previously reported signal by a brown dwarf around NGC4349 No. 127 is presumably produced by stellar activity modulation. The long-term monitoring of several red giants in open clusters has allowed us to find periodic RV variations in several stars. However, we also show that the follow-up of this kind of stars should last more than one orbital period to detect long-term signals of stellar origin. This work warns that although it is possible to detect planets around red giants, large-amplitude, long-period RV modulations do exist in such stars that can mimic the presence of an orbiting planetary body. Therefore, we need to better understand how such RV modulations behave as stars evolve along the Red Giant Branch and perform a detailed study of all the possible stellar-induced signals (e.g. spots, pulsations, granulation) to comprehend the origin of RV variations.
- ID:
- ivo://CDS.VizieR/J/ApJ/889/176
- Title:
- Very low-mass binaries with Gaia DR2 data
- Short Name:
- J/ApJ/889/176
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report the discovery of WISE 2150-7520AB (W2150AB): a widely separated (~341au) very low-mass L1+T8 co-moving system. The system consists of the previously known L1 primary 2MASS J21501592-7520367 and a newly discovered T8 secondary found at position 21:50:18.99-75:20:54.6 (MJD=57947) using Wide-field Infrared Survey Explorer data via the Backyard Worlds: Planet 9 citizen science project. We present Spitzer ch1 and ch2 photometry (ch1-ch2=1.41+/-0.04mag) of the secondary and Folded-port InfraRed Echellette prism spectra of both components. The sources show no peculiar spectral or photometric signatures, indicating that each component is likely field age. Using all observed data and the Gaia DR2 parallax of 41.3593+/-0.2799mas for W2150A we deduce fundamental parameters of log(L_bol_/L_{sun}_)=-3.69+/-0.01, Teff=2118+/-62K, and an estimated mass=72+/-12M_Jup_ for the L1 and log(L_bol_/L_{sun}_)=-5.64+/-0.02, Teff=719+/-61K, and an estimated mass=34+/-22M_Jup_ for the T8. At a physical separation of ~341au this system has E_bin_=10^41^erg, making it the lowest binding energy system of any pair with M_tot_<0.1M_{sun}_ not associated with a young cluster. It is equivalent in estimated mass ratio, E_bin_, and physical separation to the ~2Myr M7.25+M8.25 binary brown dwarf 2MASS J11011926-7732383AB (2M1101AB) found in the Chameleon star-forming region. W2150AB is the widest companion system yet observed in the field where the primary is an L dwarf or later.