- ID:
- ivo://CDS.VizieR/J/A+A/641/A156
- Title:
- IC 4665 multi-band photometry
- Short Name:
- J/A+A/641/A156
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Debris discs orbiting young stars are key to understand dust evolution and the planetary formation process.We take advantage of a recent membership analysis of the 30Myr nearby open cluster IC 4665 based on the Gaia and DANCe surveys to revisit the disc population of this cluster. We aim to study the disc population of IC 4665 using Spitzer (MIPS and IRAC) and WISE photometry. We use several colour-colour diagrams with empirical photospheric sequences to detect the sources with an infrared excess. Independently, we also fit the spectral energy distribution (SED) of our debris disc candidates with the Virtual Observatory SED analyser (VOSA) which is capable of automatically detecting infrared excesses and provides effective temperature estimates. We find six candidates debris disc host-stars (five with MIPS and one with WISE) and two of them are new candidates. We estimate a disc fraction of 24+/-10% for the B-A stars, where our sample is expected to be complete. This is similar to what has been reported in other clusters of similar ages (Upper Centaurus Lupus, Lower Centaurus Crux, the $\beta$ Pictoris moving group, and the Pleiades). For solar type stars we find a disk fraction of 9+/-9%, lower than that observed in regions with comparable ages. Our candidates debris disc host-stars are excellent targets to be studied with ALMA or the future James Webb Space Telescope (JWST).
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Search Results
1682. Ic photometry of IC 348
- ID:
- ivo://CDS.VizieR/J/MNRAS/358/341
- Title:
- Ic photometry of IC 348
- Short Name:
- J/MNRAS/358/341
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a photometric study of I-band variability in the young cluster IC 348. The main purpose of the study was to identify periodic stars. In all, we find 50 periodic stars, of which 32 were previously unknown. For the first time in IC 348, we discover periods in significant numbers of lower-mass stars (M<0.25M_{sun}_) and classical T Tauri stars.
- ID:
- ivo://CDS.VizieR/J/ApJ/873/132
- Title:
- ICRF3 radio-loud quasars with Gaia DR2 data
- Short Name:
- J/ApJ/873/132
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We investigate a sample of 3413 International Celestial Reference Frame (ICRF3) extragalactic radio-loud sources with accurate positions determined by very long baseline interferometry in the S/X band, mostly active galactic nuclei and quasars, which are cross-matched with optical sources in the second Gaia data release (Gaia DR2). The main goal of this study is to determine a core sample of astrometric objects that define the mutual orientation of the two fundamental reference frames, the Gaia (optical) and the ICRF3 (radio) frames. The distribution of normalized offsets between the VLBI sources and their optical counterparts is non-Rayleigh, with a deficit around the modal value and a tail extending beyond the 3{sigma} confidence level. A few filters are applied to the sample in order to discard double cross-matches, confusion sources, and Gaia astrometric solutions of doubtful quality. Panoramic Survey Telescope and Rapid Response System and Dark Energy Survey stacked multicolor images are used to further deselect objects that are less suitable for precision astrometry, such as extended galaxies, double and multiple sources, and obvious misidentifications. After this cleaning, 2643 quasars remain, of which 20% still have normalized offset magnitudes exceeding 3, or a 99% confidence level. We publish a list of 2119 radio-loud quasars of prime astrometric quality. The observed dependence of binned median offset on redshift shows the expected decline at small redshifts, but also an unexpected rise at z~1.6, which may be attributed to the emergence of the CIV emission line in the Gaia's G band. The Gaia DR2 parallax zero-point is found to be color-dependent, suggesting an uncorrected instrumental calibration effect.
1684. IC 2714 UBV photometry
- ID:
- ivo://CDS.VizieR/J/A+AS/107/39
- Title:
- IC 2714 UBV photometry
- Short Name:
- J/A+AS/107/39
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- UBV photoelectric photometry for 204 stars in the field of the southern open cluster IC 2714 supplemented by DDO and Washington photometry and Coravel radial velocities of 14 probable red giants, are presented. The analysis of the photometric and kinematical data yielded 132 probable members and 13 possible members. IC 2714 contains one variable star and 11 red giant members, one of them being a spectroscopic binary. Two red giants are either binaries or non-members. The reddening across the cluster is slightly variable, the mean value is E(B-V)=0.36. The cluster distance-modulus is 11.68, corresponding to a distance of 1320(+/-120)pc and the mean radial velocity is -14.1+/-0.3km/s. The age, determined by fitting isochrones with core overshooting turned out to be log(t)=8.5, corresponding to 3.2 10^8 yr. A metal abundance [Fe/H]=-0.12+/-0.09 relative to the Sun and other fundamental parameters are determined. The luminosity function of the bright members of IC 2714 in good agreement with that determined by Taff (1974AJ.....79.1280T). For a description of the UBV, DDO and Washington photometric system, see e.g. <GCPD/01>, <GCPD/12> and <GCPD/45>
1685. IC 4651 uvby photometry
- ID:
- ivo://CDS.VizieR/J/A+A/361/929
- Title:
- IC 4651 uvby photometry
- Short Name:
- J/A+A/361/929
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- New accurate CCD photometry in the u, v, b and y bands of the Stroemgren system filters has been obtained for 17640 stars to approximately. V=20mag in a approximately 21' x 21' field centered on the intermediate-age open cluster IC 4651. The observations was obtained with the Danish 1.5-m telescope at the European Southern Observatory, La Silla, Chile. Table 1 contains information about the Date, Night, Filter, Exposure time, Airmass, CCD rotation angle, and RA- , DE-offsets for all 89 frames. Table 2 gives cross-references between the MEI-system (this paper) and the Lindoff (1972A&AS....7..231L, IC 4651 NNN), Eggen (1971ApJ...166...87E, Cl* IC 4651 Egg NN), Anthony-Twarog & Twarog (1987AJ.....94.1222A, Cl* IC 4651 AT 1-NNN, Cl* IC 4651 AT 2-NN), and Anthony-Twarog et al. (1988AJ.....95.1453A, Cl* IC 4651 AMC I-NNN, Cl* IC 4651 AMC NNNN) identification numbers. Table 3 is the final catalogue of the new Stroemgren uvby photometry, ordered by MEI identification number. For each star, it gives the MEI number, Global CCD x- and y-coordinates, J2000 coordinates , the new y, b, v, and u magnitudes on the standard system, number of detections of the individual stars, and their mean errors.
1686. IC 2602 VRI photometry
- ID:
- ivo://CDS.VizieR/J/A+AS/126/81
- Title:
- IC 2602 VRI photometry
- Short Name:
- J/A+AS/126/81
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results of VRI photometry of the young open cluster IC 2602. Two 15x15arcmin^2^ fields were observed in February and May 1991 using the 1-m Swope telescope at Las Campanas. Using theoretical isochrones obtained from D'Antona & Mazzitelli (1994ApJS...90..467D), and allowing for observational and other uncertainties, we identify 78 primary candidate members with 12<V<18.5 from their positions on colour-magnitude diagrams. We compare the cluster field with an offset field of similar galactic latitude and estimate the contamination due to background stars to be large, >=50%, as might be expected given its low galactic latitude. We also compare our photometry with that given for the X-ray detected stars of Randich et al. (1995A&A...300..134R) present complimentary narrow band H{alpha} photometry for a subset of the stars.
- ID:
- ivo://CDS.VizieR/J/AJ/158/16
- Title:
- Identification of RR Lyrae stars from the DES
- Short Name:
- J/AJ/158/16
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Many studies have shown that RR Lyrae variable stars (RRL) are powerful stellar tracers of Galactic halo structure and satellite galaxies. The Dark Energy Survey (DES), with its deep and wide coverage (g~23.5 mag in a single exposure; over 5000 deg^2^) provides a rich opportunity to search for substructures out to the edge of the Milky Way halo. However, the sparse and unevenly sampled multiband light curves from the DES wide-field survey (a median of four observations in each of grizY over the first three years) pose a challenge for traditional techniques used to detect RRL. We present an empirically motivated and computationally efficient template-fitting method to identify these variable stars using three years of DES data. When tested on DES light curves of previously classified objects in SDSS stripe 82, our algorithm recovers 89% of RRL periods to within 1% of their true value with 85% purity and 76% completeness. Using this method, we identify 5783 RRL candidates, ~28% of which are previously undiscovered. This method will be useful for identifying RRL in other sparse multiband data sets.
- ID:
- ivo://CDS.VizieR/J/ApJS/254/26
- Title:
- Identifying 3FHL. V. CTIO-COSMOS spectra
- Short Name:
- J/ApJS/254/26
- Date:
- 19 Jan 2022 00:35:09
- Publisher:
- CDS
- Description:
- As a follow-up to the optical spectroscopic campaign aimed at achieving completeness in the Third Catalog of Hard Fermi-LAT Sources (3FHL), we present here the results of a sample of 28 blazars of an uncertain type observed using the 4m telescope at Cerro Tololo Inter-American Observatory in Chile. Out of these 28 sources, we find that 25 are BL Lacertae objects (BL Lacs) and 3 are flat-spectrum radio quasars (FSRQs). We measure redshifts or lower limits for 16 of these blazars, and it is observed that the 12 remaining blazars have featureless optical spectra. These results are part of a more extended optical spectroscopy follow-up campaign for 3FHL blazars, where, until now, 51 blazars of an uncertain type have been classified into BL Lac and FSRQ categories. Furthermore, this campaign has resulted in redshift measurements and lower limits for 15 of these sources. Our results contribute toward attaining a complete sample of blazars above 10 GeV, which then will be crucial in extending our knowledge on blazar emission mechanisms and the extragalactic background light.
- ID:
- ivo://CDS.VizieR/J/AJ/152/108
- Title:
- i filter photometry for HATS-25 through HATS-30
- Short Name:
- J/AJ/152/108
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report six new inflated hot Jupiters (HATS-25b through HATS-30b) discovered using the HATSouth global network of automated telescopes. The planets orbit stars with V magnitudes in the range of ~12-14 and have masses in the largely populated 0.5M_J_--0.7M_J_ region of parameter space but span a wide variety of radii, from 1.17R_J_ to 1.75R_J_. HATS-25b, HATS-28b, HATS-29b, and HATS-30b are typical inflated hot Jupiters (R_p_=1.17--1.26R_J_) orbiting G-type stars in short period (P=3.2-4.6 days) orbits. However, HATS-26b (R_p_=1.75R_J_, P=3.3024days) and HATS-27b (R_p_=1.50R_J_, P=4.6370days) stand out as highly inflated planets orbiting slightly evolved F stars just after and in the turn-off points, respectively, which are among the least dense hot Jupiters, with densities of 0.153g/cm^3^ and 0.180g/cm^3^, respectively. All the presented exoplanets but HATS-27b are good targets for future atmospheric characterization studies, while HATS-27b is a prime target for Rossiter-McLaughlin monitoring in order to determine its spin-orbit alignment given the brightness (V=12.8) and stellar rotational velocity (vsini~9.3km/s) of the host star. These discoveries significantly increase the number of inflated hot Jupiters known, contributing to our understanding of the mechanism(s) responsible for hot Jupiter inflation.
- ID:
- ivo://CDS.VizieR/J/A+A/581/A65
- Title:
- IFU observations of NGC 4191
- Short Name:
- J/A+A/581/A65
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We here distinguish two counter-rotating stellar components in NGC 4191 and characterize their physical properties such as kinematics, size, morphology, age, metallicity. We obtained integral field spectroscopic observations with VIRUS-W and used a spectroscopic decomposition technique to separate the contribution of two stellar components to the observed galaxy spectrum. We also performed a photometric decomposition, modeling the galaxy with a Sersic bulge and two exponential disks of different scale length, with the aim of associating these structural components with the kinematic components. We then measured the equivalent width of the absorption line indices on the best-fit models that represent the kinematic components and compared our measurements to the predictions of stellar population models that also account for the variable abundance ratio of {alpha} elements.
