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- ID:
- ivo://CDS.VizieR/J/A+A/417/479
- Title:
- RI photometry of NGC 185 carbon stars
- Short Name:
- J/A+A/417/479
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We used the CFH12K wide field camera to survey the carbon star population of NGC 185 using the CN-TiO technique. 145 C stars are identified with a mean <I>=19.99+/-0.05, corresponding to <M_I_>=-4.41+/-0.05, a mean luminosity similar to what was recently found for the C star population of NGC 147. The stellar surface density profile of NGC 185 follows a power law with an exponential scale length of 2.53+/-0.07'. The surface density of C stars follows also a power law but with a smaller scale length, 1.56+/-0.06, demonstrating that the intermediate-age population of NGC 185 is more concentrated than its old population. A tidal radius, r_t_=22.5+/-2.2' is determined from red giant star counts. The C/M ratio of NGC 185 is 0.17+/-0.02 with no apparent sign of a radial gradient. We compare the carbon star populations of NGC 185 and NGC 147 to conclude that it is unlikely that they form a close pair.
- ID:
- ivo://CDS.VizieR/J/AJ/125/3037
- Title:
- RI photometry of NGC 205 carbon stars
- Short Name:
- J/AJ/125/3037
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a CFH12K survey of the carbon stars in NGC 205 and its surrounding field. We find that the number of C stars in NGC 205 is low (~500) for its luminosity and that very few C stars are seen outside of the 10 isophote, suggesting tidal stripping by M31. Their <M_I_>=-4.54, a magnitude nearly identical to what has been found in other galaxies with numerous C stars. Stars with accurate (R-I) photometry, to I~22.5, are used to determine the outer profile of NGC 205.
- ID:
- ivo://CDS.VizieR/J/ApJS/202/19
- Title:
- riz photometry in Cyg OB2
- Short Name:
- J/ApJS/202/19
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In order to fully understand the gravitational collapse of molecular clouds, the star formation process, and the evolution of circumstellar disks, these phenomena must be studied in different Galactic environments with a range of stellar contents and positions in the Galaxy. The young massive association Cygnus OB2, in the Cygnus-X region, is a unique target to study how star formation and the evolution of circumstellar disks proceed in the presence of a large number of massive stars. We present a catalog obtained with recent optical observations in the r, i, z filters with OSIRIS, mounted on the 10.4m Gran Telescopio CANARIAS telescope, which is the deepest optical catalog of CygOB2 to date. The catalog consists of 64,157 sources down to M=0.15M_{sun}_ at the adopted distance and age of Cyg OB2. A total of 38,300 sources have good photometry in all three bands. We combined the optical catalog with existing X-ray data of this region, in order to define the cluster locus in the optical diagrams. The cluster locus in the r-i versus i-z diagram is compatible with an extinction of the optically selected cluster members in the 2.64m<A_V_<5.57m range. We derive an extinction map of the region, finding a median value of A_V_=4.33m in the center of the association, decreasing toward the northwest. In the color-magnitude diagrams, the shape of the distribution of main-sequence stars is compatible with the presence of an obscuring cloud in the foreground ~850+/-25pc from the Sun.
- ID:
- ivo://CDS.VizieR/J/AJ/155/51
- Title:
- Robo-AO binary star systems in 3 open clusters
- Short Name:
- J/AJ/155/51
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We identify and roughly characterize 66 candidate binary star systems in the Pleiades, Praesepe, and NGC 2264 star clusters, based on robotic adaptive optics imaging data obtained using Robo-AO at the Palomar 60" telescope. Only ~10% of our imaged pairs were previously known. We detect companions at red optical wavelengths, with physical separations ranging from a few tens to a few thousands of au. A three-sigma contrast curve generated for each final image provides upper limits to the brightness ratios for any undetected putative companions. The observations are sensitive to companions with a maximum contrast of ~6^m^ at larger separations. At smaller separations, the mean (best) raw contrast at 2" is 3.8^m^ (6^m^), at 1" is 3.0^m^ (4.5^m^), and at 0.5" is 1.9^m^ (3^m^). Point-spread function subtraction can recover nearly the full contrast in the closer separations. For detected candidate binary pairs, we report separations, position angles, and relative magnitudes. Theoretical isochrones appropriate to the Pleiades and Praesepe clusters are then used to determine the corresponding binary mass ratios, which range from 0.2 to 0.9 in q=m_2_/m_1_. For our sample of roughly solar-mass (FGK type) stars in NGC 2264 and sub-solar-mass (K and early M-type) primaries in the Pleiades and Praesepe, the overall binary frequency is measured at ~15.5%+/-2%. However, this value should be considered a lower limit to the true binary fraction within the specified separation and mass ratio ranges in these clusters, given that complex and uncertain corrections for sensitivity and completeness have not been applied.
- 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.
- 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/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/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.
