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6081. Southern ultracool dwarfs in young moving groups
ID:
ivo://CDS.VizieR/J/MNRAS/402/575
Title:
Southern ultracool dwarfs in young moving groups
Short Name:
J/MNRAS/402/575
Date:
21 Oct 2021
Publisher:
CDS
Description:
We associate 132 low-mass ultracool dwarfs in the southern hemisphere as candidate members of five moving groups (MGs) using photometric and astrometric selection techniques. Of these objects, we present high-resolution spectroscopy for seven candidates and combine these with previous measurements from the literature to determine spectral types and radial velocities. We thus constrain distance and space motion spectroscopically, allowing the kinematic membership of the MGs to be assessed. Possible membership of MGs has allowed ages and metallicities to be constrained for these objects and evolutionary models have been used to estimate their mass. We estimate that up to ~75 of our candidate MG members should be genuine, and discuss future work that will confirm and exploit this major new sample.
6082. South Galactic cap MCT blue objects
ID:
ivo://CDS.VizieR/J/AJ/119/241
Title:
South Galactic cap MCT blue objects
Short Name:
J/AJ/119/241
Date:
21 Oct 2021
Publisher:
CDS
Description:
Results for the south Galactic cap region of the Montreal-Cambridge-Tololo survey of blue subluminous stars are presented. This region overlaps the 840 deg^2^ region studied almost three decades ago by Slettebak & Brundage (1971AJ.....76..338S). We present a list of equatorial coordinates, photographic photometry, and spectroscopic identifications, as well as finding charts, for 188 blue objects [(U-B)_pg_<=-0.6] brighter than B_pg_=16.5 in this area. Completeness of the survey and comparisons with other similar efforts are discussed.
6083. Space telescope RM project. III. NGC 5548 LCs
ID:
ivo://CDS.VizieR/J/ApJ/821/56
Title:
Space telescope RM project. III. NGC 5548 LCs
Short Name:
J/ApJ/821/56
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present ground-based optical photometric monitoring data for NGC5548, part of an extended multiwavelength reverberation mapping campaign. The light curves have nearly daily cadence from 2014 January to July in nine filters (BVRI and ugriz). Combined with ultraviolet data from the Hubble Space Telescope and Swift, we confirm significant time delays between the continuum bands as a function of wavelength, extending the wavelength coverage from 1158{AA} to the z band (~9160{AA}). We find that the lags at wavelengths longer than the V band are equal to or greater than the lags of high-ionization-state emission lines (such as HeII{lambda}1640 and {lambda}4686), suggesting that the continuum-emitting source is of a physical size comparable to the inner broad-line region (BLR). The trend of lag with wavelength is broadly consistent with the prediction for continuum reprocessing by an accretion disk with {tau}{propto}{lambda}^4/3^. However, the lags also imply a disk radius that is 3 times larger than the prediction from standard thin-disk theory, assuming that the bolometric luminosity is 10% of the Eddington luminosity (L=0.1L_Edd_). Using optical spectra from the Large Binocular Telescope, we estimate the bias of the interband continuum lags due to BLR emission observed in the filters. We find that the bias for filters with high levels of BLR contamination (~20%) can be important for the shortest continuum lags and likely has a significant impact on the u and U bands owing to Balmer continuum emission.
6084. Space telescope RM project. II. Swift data
ID:
ivo://CDS.VizieR/J/ApJ/806/129
Title:
Space telescope RM project. II. Swift data
Short Name:
J/ApJ/806/129
Date:
21 Oct 2021
Publisher:
CDS
Description:
Recent intensive Swift monitoring of the Seyfert 1 galaxy NGC 5548 yielded 282 usable epochs over 125 days across six UV/optical bands and the X-rays. This is the densest extended active galactic nucleus (AGN) UV/optical continuum sampling ever obtained, with a mean sampling rate <0.5 day. Approximately daily Hubble Space Telescope UV sampling was also obtained. The UV/optical light curves show strong correlations (r_max_=0.57-0.90) and the clearest measurement to date of interband lags. These lags are well-fit by a {tau}{propto}{lambda}^4/3^ wavelength dependence, with a normalization that indicates an unexpectedly large disk radius of ~0.35+/-0.05lt-day at 1367{AA}, assuming a simple face-on model. The U band shows a marginally larger lag than expected from the fit and surrounding bands, which could be due to Balmer continuum emission from the broad-line region as suggested by Korista and Goad. The UV/X-ray correlation is weaker (r_max_<0.45) and less consistent over time. This indicates that while Swift is beginning to measure UV/optical lags in general agreement with accretion disk theory (although the derived size is larger than predicted), the relationship with X-ray variability is less well understood. Combining this accretion disk size estimate with those from quasar microlensing studies suggests that AGN disk sizes scale approximately linearly with central black hole mass over a wide range of masses.
6085. Spaghetti Survey
ID:
ivo://CDS.VizieR/J/AJ/120/2496
Title:
Spaghetti Survey
Short Name:
J/AJ/120/2496
Date:
21 Oct 2021
Publisher:
CDS
Description:
The Spaghetti project is a pencil-beam photometric and spectroscopic survey designed to identify structure in the Galactic halo. Four-color stellar photometry in the modified Washington filter set is used to identify halo stars for spectroscopic observations. The filters include C, M, T2 and DDO51. The fields in the survey are chosen from high Galactic-latitude positions with low reddening and no stars as bright as SAO stars. Thus far we have imaged 134 fields covering a total area of 52deg^2^. These fields are listed in table1.dat. Due to weather, the only fully calibrated photometry was measured from images taken with the BTC ccd mosaic camera on the CTIO 4m telescope in April 1999. Table4.dat lists these stars from the 53 BTC fields, which covers a total area of 13 square degrees. These data include only those stars whose measurement errors are less than 0.04 in all four filters (32655 total stars). Photometric measurements of stars in the other fields will be published as soon as they can be fully calibrated. See <GCPD/48> for a short description of the Washington Photometric system.
6086. S-PASS & NVSS bright extragalactic radio sources
ID:
ivo://CDS.VizieR/J/ApJ/829/5
Title:
S-PASS & NVSS bright extragalactic radio sources
Short Name:
J/ApJ/829/5
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present a polarization catalog of 533 extragalactic radio sources that have a 2.3GHz total intensity above 420mJy from the S-band Polarization All Sky Survey, S-PASS, with corresponding 1.4GHz polarization information from the NRAO VLA Sky Survey, NVSS. We studied the selection effects and found that fractional polarization, {pi}, of radio objects at both wavelengths depends on the spectral index, the source magnetic field disorder, the source size, and depolarization. The relationship between depolarization, spectrum, and size shows that depolarization occurs primarily in the source vicinity. The median {pi}_2.3_ of resolved objects in NVSS is approximately two times larger than that of unresolved sources. Sources with little depolarization are ~2 times more polarized than both highly depolarized and re-polarized sources. This indicates that intrinsic magnetic field disorder is the dominant mechanism responsible for the observed low fractional polarization of radio sources at high frequencies. We predict that number counts from polarization surveys will be similar at 1.4GHz and at 2.3GHz, for fixed sensitivity, although ~10% of all sources may currently be missing because of strong depolarization. Objects with {pi}_1.4_~{pi}_2.3_>=4% typically have simple Faraday structures, so they are most useful for background samples. Almost half of flat-spectrum ({alpha}>=-0.5) and ~25% of steep-spectrum objects are re-polarized. Steep-spectrum, depolarized sources show a weak negative correlation of depolarization with redshift in the range 0<z<2.3. Previous non-detections of redshift evolution are likely due the inclusion of re-polarized sources as well.
6087. Spatial distribution of brown dwarfs in Taurus
ID:
ivo://CDS.VizieR/J/ApJ/645/676
Title:
Spatial distribution of brown dwarfs in Taurus
Short Name:
J/ApJ/645/676
Date:
21 Oct 2021
Publisher:
CDS
Description:
By combining photometry from the 2MASS Point Source Catalog and the USNO-B1.0 catalog with optical and infrared spectroscopy, I have performed a search for young brown dwarfs in an area of 225deg^2^ encompassing all of the Taurus star-forming region (tau~1Myr). From this work, I have discovered 22 new members of Taurus, 5 of which were independently found by Guieu and coworkers (2006, Cat. <J/A+A/446/485>). Sixteen of these new members have spectral types later than M6 and thus are likely to be brown dwarfs according to the theoretical evolutionary models of Chabrier and Baraffe (2000ApJ...542..464C). After adding these new members to the previously known members of Taurus, I have compared the spatial distributions of stars and brown dwarfs across the entire region. I find no statistically significant difference between these two distributions. Taurus does not contain the large, extended population of brown dwarfs that has been predicted by some embryo ejection models for the formation of brown dwarfs. However, these results are consistent with other ejection models, as well as models in which stars and brown dwarfs share a common formation mechanism.
6088. Spatial distribution of magnetic CP stars
ID:
ivo://CDS.VizieR/J/other/Ap/46.234
Title:
Spatial distribution of magnetic CP stars
Short Name:
J/other/Ap/46.23
Date:
21 Oct 2021
Publisher:
CDS
Description:
On the basis of analysis of original publications and our own measurements a Cataloque of magnetic chemically peculiar (CP) upper-main sequence stars has been established. The sample includes 211 magnetic CP stars with magnetic fields ranging from hundreds of gauss to dozens of kilogauss, for 49 of them the surface magnetic field (B_e_) has been measured from the Zeeman splitting. The CP stars may be divided into 3 groups: reversing stars (table3, longitudinal field B_e_ changes its sign), non-reversing (table4, B_e_ keeps the same sign), and poorly studied stars.
6089. Speckle holography of binary systems with OAN-SPM
ID:
ivo://CDS.VizieR/J/AJ/160/9
Title:
Speckle holography of binary systems with OAN-SPM
Short Name:
J/AJ/160/9
Date:
08 Dec 2021
Publisher:
CDS
Description:
We present our first results of multiband Speckle Holography of components of visual double stars. The observations were performed during 2019-April at the 2.1m telescope at the Observatorio Astronomico Nacional at Sierra de San Pedro Martir (Mexico). We have observed 190 double stars with separation between 3" and 5". The position angle, separation and magnitude difference in three broadband optical filters (VRI) for these systems are provided. For 15 systems we found different interesting features, we have identified a close component for 9 of those systems; 5 of them are newly discovered. In the remaining 6 systems, although unresolved, we found elongations that we have been able to derive astrometric parameters if proven to be a (newly discovered) close component. This corresponds to about 8% of the sample presenting a certain feature in one of the components and about 5% of the sample having a confirmed close component.
6090. Speckle interferometry at SOAR in 2018
ID:
ivo://CDS.VizieR/J/AJ/158/48
Title:
Speckle interferometry at SOAR in 2018
Short Name:
J/AJ/158/48
Date:
21 Oct 2021
Publisher:
CDS
Description:
The results of speckle interferometric observations at the 4.1 m Southern Astrophysical Research Telescope (SOAR) in 2018 are given, totaling 3097 measurements of 2427 resolved pairs with separations from 11 mas to 5.9" (median 0.15", magnitude difference up to 7 mag) and nonresolutions of 624 targets. This work continues our long-term speckle program. Its main goal is to monitor orbital motion of close binaries, including members of high-order hierarchies and Hipparcos pairs in the solar neighborhood. Also, pre-main-sequence stars in the Orion OB1 association were surveyed, resolving 26 out of 118 targets. In addition, we report the discovery of 35 new companions among field visual multiples (some of which are likely optical) and first-time resolutions of another 31 pairs. By combining the measurements given here with the published ones, we computed 76 orbits for the first time and updated orbital elements of 34 visual binaries. Their periods range from 0.65 to 1100 yr, and their quality varies from first tentative solutions of grade 5 to accurate elements of grades 1 and 2. Finally, a list of 53 spurious pairs discovered by various techniques and unresolved at SOAR is given.