- ID:
- ivo://CDS.VizieR/J/ApJ/799/4
- Title:
- Robo-AO observations of binary stars
- Short Name:
- J/ApJ/799/4
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We conducted a survey of nearby binary systems composed of main sequence stars of spectral types F and G in order to improve our understanding of the hierarchical nature of multiple star systems. Using Robo-AO, the first robotic adaptive optics instrument, we collected high angular resolution images with deep and well-defined detection limits in the Sloan Digital Sky Survey i' band. A total of 695 components belonging to 595 systems were observed. We prioritized observations of faint secondary components with separations over 10" to quantify the still poorly constrained frequency of their subsystems. Of the 214 secondaries observed, 39 contain such subsystems; 19 of those were discovered with Robo-AO. The selection-corrected frequency of secondary subsystems with periods from 10^3.5^ to 10^5^ days is 0.12+/-0.03, the same as the frequency of such companions to the primary. Half of the secondary pairs belong to quadruple systems where the primary is also a close pair, showing that the presence of subsystems in both components of the outer binary is correlated. The relatively large abundance of 2+2 quadruple systems is a new finding, and will require more exploration of the formation mechanism of multiple star systems. We also targeted close binaries with periods less than 100 yr, searching for their distant tertiary components, and discovered 17 certain and 2 potential new triples. In a subsample of 241 close binaries, 71 have additional outer companions. The overall frequency of tertiary components is not enhanced, compared to all (non-binary) targets, but in the range of outer periods from 10^6^ to 10^7.5^ days (separations on the order of 500AU), the frequency of tertiary components is 0.16+/-0.03, exceeding the frequency of similar systems among all targets (0.09) by almost a factor of two. Measurements of binary stars with Robo-AO allowed us to compute first orbits for 9 pairs and to improve orbits of another 11 pairs.
Number of results to display per page
Search Results
- ID:
- ivo://CDS.VizieR/J/A+A/591/A96
- Title:
- Robust detection of CID double stars in SDSS
- Short Name:
- J/A+A/591/A96
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Sloan Digital Sky Survey (SDSS) offers a unique possibility of not only detecting colour induced displacement (CID) double stars but also confirming these detections. Successive cuts are applied to the SDSS data release (DR) 12 database to reduce the size of the sample under consideration. The resulting dataset is then screened with a criterion based on the distance and orientation of the photocentres in different photometric bands. About 3200 distinct objects are classified as CID double stars, 40 of which are confirmed with at least a second detection. A consistency check further validates these detections.
- ID:
- ivo://CDS.VizieR/J/ApJS/247/53
- Title:
- ROGUE. I. SDSS galaxies with FIRST
- Short Name:
- J/ApJS/247/53
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the catalog of Radio sources associated with Optical Galaxies and having Unresolved or Extended morphologies I (ROGUE I), consisting of 32616 spectroscopically selected galaxies. It is the largest handmade catalog of this kind, obtained by cross-matching galaxies from the Sloan Digital Sky Survey (SDSS) Data Release 7 and radio sources from both the First Images of Radio Sky at Twenty Centimetre (FIRST) survey and the NRAO Very Large Array Sky Survey, without imposing a limit on the radio flux densities. The catalog provides a visual classification of radio and optical morphologies of galaxies presenting a FIRST core within 3" of the optical position. The radio morphological classification is performed by examining the radio-optical overlays of linear sizes equal to 1Mpc at the source distance, while the 120" image snapshots from the SDSS database are used for optical classification. The results of our search are as follows: (i) single-component unresolved and elongated radio sources constitute the major group in the ROGUE I catalog (~90%), and ~8% exhibit extended morphologies; (ii) samples of 269, 730, and 115 Fanaroff-Riley (FR) type I, II, and hybrid galaxies, respectively, are presented; (iii) we report 55 newly discovered giant/possible giant, 16 double-double, 9 X-shaped, and 25 Z-shaped radio sources; (iv) on the optical front, most galaxies have elliptical morphologies (~62%) while spirals form the second major category (~17%) followed by distorted (~12%) and lenticular (~7%) morphologies; and (v) division between the FR I and the FR II sources in the radio-optical luminosity plane is blurred, in tune with recent studies.
- ID:
- ivo://CDS.VizieR/J/A+A/328/349
- Title:
- Role of Convection in A, F, and G stars
- Short Name:
- J/A+A/328/349
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We discuss the effects of convection on the theoretical uvby colours of A, F, and G stars. The standard mixing-length theory atlas9 models of Kurucz (1993, ATLAS9, SAO, Cambridge, USA), with and without approximate overshooting, are compared to models using the turbulent convection theory proposed by Canuto & Mazzitelli (1991ApJ...370..295C, 1992ApJ...389..724C) and implemented by Kupka (1996, ASPConf. Proc. 108, 73). Comparison with fundamental Teff and log g stars reveals that the Canuto & Mazzitelli models give results that are generally superior to standard mixing-length theory (MLT) without convective overshooting. MLT models with overshooting are found to be clearly discrepant. This is supported by comparisons of non-fundamental stars, with Teff obtained from the Infrared Flux Method and log g from stellar evolutionary models for open cluster stars. The Canuto & Mazzitelli theory gives values of (b-y)0 and c0 that are in best overall agreement with observations. Investigations of the m0 index reveal that all of the treatments of convection presented here give values that are significantly discrepant for models with Teff<6000K. It is unclear as to whether this is due to problems with the treatment of convection, missing opacity, or some other reason. None of the models give totally satisfactory m0 indices for hotter stars, but the Canuto & Mazzitelli models are in closest overall agreement above 7000K. Grids of uvby colours, based on the CM treatment of convection, are presented. These grids represent an improvement over the colours obtained from models using the mixing-length theory. The agreement with fundamental stars enables the colours to be used directly without the need for semi-empirical adjustments that were necessary with the earlier colour grids. For a description of the uvby photometric system, see e.g. <GCPD/04>
- ID:
- ivo://CDS.VizieR/J/A+A/378/30
- Title:
- ROSAT-BSC galaxy identifications
- Short Name:
- J/A+A/378/30
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In a correlation study of the ROSAT All-Sky Survey Bright Source Catalogue (RASS-BSC, Cat. <XI/10>) with the Catalogue of Principal Galaxies (PGC, Cat. <VII/119>) 904 X-ray sources were found that possess possible extragalactic counterparts within a search radius of 100". File table1 contains 1124 optical galaxy entries and 904 relevant X-ray candidates/counterparts from the ROSAT All-Sky Survey. Besides a compilation of X-ray and optical parameters for each source, also the results of an identification screening are given. 547 optical/X-ray correlations have been quoted as reliable identifications. The 904 optical images with X-ray overlay contours (xID_nnn.ps.gz) used in the screening process are added for each user's own judgement.
- ID:
- ivo://CDS.VizieR/J/A+A/346/586
- Title:
- Rotating models of A and F stars
- Short Name:
- J/A+A/346/586
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Magnitude differences between rotating and non-rotating copartners for a grid of models with solar metallicity are tabulated here. The results are expressed in terms of the dimensionless angular velocity w-bar- defined in Eq.(1) of the paper, the angle of inclination i and the atmospheric parameters T_e_ and g_e_ defined in Eqs.(22) and (21), respectively. To obtain the absolute magnitudes for a given rotating model, the magnitudes of a non-rotating model with T_eff_=T_e_, g=g_e_ and the same intrinsic luminosity must be added. Results are given for the filters in the Geneva, Johnson and Stroemgren systems. Eq (1): w-bar = {Omega}/{Omega}_c_, where {Omega} is the angular velocity of the star, and {Omega}_c_^2^=8GM/(27R^3^_p_), where M is the mass and R_p_ the polar radius.
- ID:
- ivo://CDS.VizieR/J/A+A/331/581
- Title:
- Rotation and activity in field M dwarfs
- Short Name:
- J/A+A/331/581
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have obtained high resolution spectra for a volume-limited sample of 118 field M dwarfs. From these observations we derive projected rotational velocities and fluxes in the H{alpha} and H{beta} lines. 8 stars are double-lined spectroscopic binaries with measured or probable periods short enough for rotation to be tidally synchronized with the orbit, and another 11 are visual binaries where we cannot yet separate the lines of the two stars. Of the remaining 99 stars, 24 have rotational velocities above our detection limit of ~2km/s, and some are quite fast rotators, including two with vsini>30km/s and one with vsini~50km/s. Given the small radii of M dwarfs, these moderate rotational velocities correspond to rather short maximum rotational periods, of only 7-8 hours.
- ID:
- ivo://CDS.VizieR/J/PAZh/27/250
- Title:
- Rotation curves for 135 edge-on galaxies
- Short Name:
- J/PAZh/27/250
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The table contains parameters for 135 edge-on galaxies. The observations were carried out with the 6-m Special Astrophysical Observatory telescope.
- ID:
- ivo://CDS.VizieR/J/ApJ/879/49
- Title:
- Rotation periods for 171 Gaia members of NGC 6811
- Short Name:
- J/ApJ/879/49
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Stellar rotation was proposed as a potential age diagnostic that is precise, simple, and applicable to a broad range of low-mass stars (<=1M_{sun}_). Unfortunately, rotation period (P_rot_) measurements of low-mass members of open clusters have undermined the idea that stars spin down with a common age dependence (i.e., P_rot{propto}age^0.5^): K dwarfs appear to spin down more slowly than F and G dwarfs. Agueros+ (2018, J/ApJ/862/33) interpreted data for the ~1.4Gyr-old cluster NGC 752 differently, proposing that after having converged onto a slow-rotating sequence in their first 600-700Myr (by the age of Praesepe), K dwarf P_rot_ stall on that sequence for an extended period of time. We use data from Gaia DR2 to identify likely single-star members of the ~1Gyr-old cluster NGC 6811 with Kepler light curves. We measure P_rot_ for 171 members, more than doubling the sample relative to the existing catalog and extending the mass limit from ~0.8 to ~0.6M_{sun}_. We then apply a gyrochronology formula calibrated with Praesepe and the Sun to 27 single G dwarfs in NGC 6811 to derive a precise gyrochronological age for the cluster of 1.04+/-0.07Gyr. However, when our new low-mass rotators are included, NGC 6811's color-P_rot_ sequence deviates away from the naive 1Gyr projection down to T_eff_~4295K (K5V, 0.7M_{sun}), where it clearly overlaps with Praesepe's. Combining these data with P_rot_ for other clusters, we conclude that the assumption that mass and age are separable dependencies is invalid. Furthermore, the cluster data show definitively that stars experience a temporary epoch of reduced braking efficiency where P_rot_ stall, and that the duration of this epoch lasts longer for lower-mass stars.
- ID:
- ivo://CDS.VizieR/J/ApJS/227/20
- Title:
- Rotation periods of asteroids using iPTF
- Short Name:
- J/ApJS/227/20
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In order to look for large super-fast rotators, in late 2014 and early 2015, five dedicated surveys covering ~188deg^2^ in the ecliptic plane have been carried out in the R-band, with ~10min cadence using the intermediate Palomar Transient Factory. Among 1029 reliable rotation periods obtained from the surveys, we discovered 1 new large super-fast rotator, (40511) 1999 RE88, and 18 other candidates. (40511) 1999 RE88 is an S-type inner main-belt asteroid with a diameter of D=1.9+/-0.3km, a rotation period of P=1.96+/-0.01hr, and a light curve amplitude of {Delta}m~1.0mag. To maintain such fast rotation, an internal cohesive strength of ~780Pa is required. Combining all known large super-fast rotators, their cohesive strengths all fall in the range of 100-1000Pa of lunar regolith. However, the number of large super-fast rotators seems to be far less than the whole asteroid population. This might indicate a peculiar asteroid group for them. Although the detection efficiency for a long rotation period is greatly reduced due to our two-day observation time span, the spin-rate distributions of this work show consistent results with Chang+ (2015, J/ApJS/219/27), after considering the possible observational bias in our surveys. It shows a number decrease with an increase of spin rate for asteroids with a diameter of 3<=D<=15km, and a number drop at a spin rate of f=5rev/day for asteroids with D<=3km.
