- ID:
- ivo://CDS.VizieR/J/ApJ/785/159
- Title:
- SONYC census of substellar objects in Lupus 3
- Short Name:
- J/ApJ/785/159
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- SONYC -Substellar Objects in Nearby Young Clusters- is a survey program to investigate the frequency and properties of substellar objects in nearby star-forming regions. We present a new imaging and spectroscopic survey conducted in the young (~1 Myr), nearby (~200 pc) star-forming region Lupus 3. Deep optical and near-infrared images were obtained with MOSAIC-II and NEWFIRM at the CTIO 4 m telescope, covering ~1.4 deg^2^ on the sky. The i-band completeness limit of 20.3 mag is equivalent to 0.009-0.02 M_{sun}_, for A_V_<=5. Photometry and 11-12 yr baseline proper motions were used to select candidate low-mass members of Lupus 3. We performed a spectroscopic follow-up of 123 candidates, using VIMOS at the Very Large Telescope, and we identify 7 probable members, among which 4 have spectral type later than M6.0 and T_eff_<=3000 K, i.e., are probably substellar in nature. Two of the new probable members of Lupus 3 appear underluminous for their spectral class and exhibit emission line spectrum with strong H_{alpha}_ or forbidden lines associated with active accretion. We derive a relation between the spectral type and effective temperature: T_eff_=(4120+/-175)-(172+/-26)xSpT, where SpT refers to the M spectral subtype between 1 and 9. Combining our results with the previous works on Lupus 3, we show that the spectral type distribution is consistent with that in other star-forming regions, as well as the derived star-to-brown dwarf ratio of 2.0-3.3. We compile a census of all spectroscopically confirmed low-mass members with spectral type M0 or later.
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- ID:
- ivo://CDS.VizieR/J/MNRAS/439/354
- Title:
- Sources around Tycho's Supernova 1572
- Short Name:
- J/MNRAS/439/354
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- With archival and new Hubble Space Telescope observations, we have refined the space-velocity measurements of the stars in the central region of the remnant of Tycho's supernova (SN) 1572, one of the historical Galactic Type Ia supernova remnants (SNRs). We derived a proper motion for Tycho-G of (pmRAcosDE;pmDE) J2000.0 =(-2.63;,-3.98)+/-(0.06;,0.04)[formal errors] +/-(0.18;0.10)[expected errors]mas/yr. If the star were at the distance of the SNR (taken here to be 2.83kpc), its velocity would be V_b_=-51+/-1.5km/s. We also reconstruct the binary orbit that Tycho-G should have followed if it were the surviving companion of SN 1572. We redetermine the Ni abundance of this star and compare it with new abundance data from stars of the Galactic disc, finding that [Ni/Fe] is about 1.7{sigma} above the Galactic trend. From the high velocity of Tycho-G perpendicular to the Galactic plane (-90+/-3km/s<=V_b_<=-45+/-1km/s, for the allowed range of distances to the star), its metallicity and its Ni excess, we find the probability of it being a chance interloper to be P<~0.00037 at most. The projected rotational velocity of the star should be below current observational limits. The projected position of Tycho-G is, within the uncertainties, consistent with the centroid of the X-ray emission of Tycho's SNR; moreover, its brightness is generally consistent with the post-explosion evolution of the luminosity of an SN companion. Among the other 23 stars having V<22mag and located within 42-arcsec from the X-ray centroid, only 4 are at distances compatible with that of the SNR, and none of them shows any peculiarity. Therefore, if even Tycho-G is not the surviving companion of SN 1572, the absence of other viable candidates does favour the merging of two white dwarfs as the producer of the SN.
- ID:
- ivo://CDS.VizieR/J/A+AS/124/437
- Title:
- Southern high proper motion stars positions
- Short Name:
- J/A+AS/124/437
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Several stars with large proper motions, cited by W.J. Luyten, were included in the preliminary programme for the HIPPARCOS mission. When performing preparatory measurements of plates, difficulties were encountered in identifying certain of these stars when relying only on published coordinates. We have taken advantage of this work which relates to the southern sky in order to determine the astrometric position of the greatest possible number of these objects, even for those which were not included in the programme.
- ID:
- ivo://CDS.VizieR/J/A+A/435/363
- Title:
- Southern Infrared Proper Motion Survey
- Short Name:
- J/A+A/435/363
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the first results from the Southern Infrared Proper Motion Survey. Using 2 Micron All Sky Survey (<II/246>) data along with that of the SuperCOSMOS sky survey (Hambly et al., 2001MNRAS.326.1279H) we have been able to produce the first widefield infrared proper motion survey. Having targeted the survey to identify nearby M, L and T dwarfs we have discovered 70 such new objects with proper motions greater than 0.5"/yr with 10 of these having proper motions in excess of 1"/yr.
- ID:
- ivo://CDS.VizieR/J/A+A/440/1061
- Title:
- Southern red high proper motion objects
- Short Name:
- J/A+A/440/1061
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results of spectroscopic follow-up observations for a sample of 71 red objects with high proper motions in the range 0.08-1.14 arcsec/yr as detected using APM and SuperCOSMOS Sky Surveys (SSS) measurements of multi-epoch photographic Schmidt plates. Red objects were selected by combining the photographic BjRI magnitudes with 2MASS near-infrared JHKs magnitudes. Some 50 of the 71 spectroscopically classified objects turn out to be late-type (>M6) dwarfs and in more detail, the sample includes 35 ultracool dwarfs with spectral types between M8 and L2, some previously reported, as well as five M-type subdwarfs, including a cool esdM6 object, SSSPM J0500-5406. Distance estimates based on the spectral types and 2MASS J magnitudes place almost all of the late-type (>M6) dwarfs within 50pc, with 25 objects located inside the 25pc limit of the catalogue of nearby stars. Most of the early-type M dwarfs are located at larger distances of 100-200pc, suggesting halo kinematics for some of them. All objects with Halpha equivalent widths larger than 10 Angstroms have relatively small tangential velocities (<50km/s). Finally, some late-type but blue objects are candidate binaries.
- ID:
- ivo://CDS.VizieR/I/138
- Title:
- Southern Reference Star Catalogue
- Short Name:
- I/138
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The positions are the combined results of observations of all participants in the Southern Reference Star (SRS) observing campaign from 1961 tO 1973. Preliminary catalogs were compiled at both the U.S. Naval Observatory (Washington) and the Pulkovo Observatory (Leningrad). The two compilations were compared, reconciled and combined to give the catalog described here. The proper motions have been culled from a number of different sources and should not be regarded as part of the SRS observed catalog. The proper motions are given principally as a means to take into account the small differences in epoch of observation between the SRS and the 2nd Cape Photographic Catalog plate material, which is at most about two years. Because of the inhomogeneous nature of the proper-motion sources and the likely presence of magnitude related systematic errors in the proper motions, they may not safely be used to extend the SRS system of positions very far from the mean epoch of observation which is about 1968. A discussion by T. Corbin of all the SRS observations including those made before and after the 1961 to 1973 campaign and their reduction to the FK4 system is at an advanced stage of preparation and will yield the desired high quality proper motions required for transferring the system to more distant epochs. Two sets of positions and proper motions are given. One set is referred to the equator and equinox of B1950.0 and the other to the equator and equinox of J2000.0. The positions are referred to the mean epoch of observation in both cases. The B1950.0 positions were linked directly to the system of FK4 by observational techniques. The J2000.0 data are based on a transformation of the B1950.0 data. The transformation was accomplished in two steps. First, FK5-FK4 differences referred to the B1950.0/FK4 system were added to the SRS positions and proper motions. The FK5-FK4 differences are those given by the analytical coefficients of H. Schwan (Astronomisches Rechen-Institut, Heidelberg). Second, the reduction from B1950.0 to J2000.0 was accomplished by using the conversion procedure described in the 1988 edition of THE ASTRONOMICAL ALMANAC (pg. B42). The (FK5-FK4) differences are given along with the average FK4 magnitude used as the input argument to Schwan's subroutines. An average FK4 magnitude was estimated for each SRS position from the average magnitude of all FK4 stars in an area on the celestial sphere bounded by a four-hour interval in right ascension and a 20-degree interval in declination centered on the SRS. All SRS less than 10 deg from the pole were treated as if they had been at -80 deg declination for the calculation of the average FK4 magnitude only. This transformation procedure gives a first order reduction from the FK4 to the FK5 system. A more precise reduction of many of the SRS catalogs observed from 1961 to 1973 is possible from a re-discussion of the FK4 star observations made concurrently with the SRS observations on a nightly basis. A program to reduce first the SRS and then the AGK3R to the FK5 system as directly as possible, going back to the nightly observations of FK4/FK5 when they are available, is now in progress at the observatory in Washington.
- 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.
- ID:
- ivo://CDS.VizieR/J/A+A/433/151
- Title:
- Spectrocopic results on ROSAT late-type stars
- Short Name:
- J/A+A/433/151
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present results of an investigation of the X-ray properties, age distribution, and kinematical characteristics of a high-galactic latitude sample of late-type field stars selected from the ROSAT All-Sky Survey (RASS). The sample comprises 254 RASS sources with optical counterparts of spectral types F to M distributed over six study areas located at |b|>~20{deg}, and Dec>=-9{deg}. A detailed study was carried out for the subsample of ~200 G, K, and M stars. Lithium abundances were determined for 179 G-M stars. Radial velocities were measured for most of the 141 G and K type stars of the sample. Combined with proper motions these data were used to study the age distribution and the kinematical properties of the sample. Based on the lithium abundances half of the G-K stars were found to be younger than the Hyades (660Myr). About 25% are comparable in age to the Pleiades (100Myr). A small subsample of 10 stars is younger than the Pleiades. They are therefore most likely pre-main sequence stars. Kinematically the PMS and Pleiades-type stars appear to form a group with space velocities close to the Castor moving group but clearly distinct from the Local Association.
- ID:
- ivo://CDS.VizieR/J/A+A/622/A110
- Title:
- Spectroscopic membership for NGC 3532
- Short Name:
- J/A+A/622/A110
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- NGC 3532 is an extremely rich open cluster embedded in the Galactic disc, hitherto lacking a comprehensive, documented membership list. We provide membership probabilities from new radial velocity observations of solar-type and low-mass stars in NGC 3532, in part as a prelude to a subsequent study of stellar rotation in the cluster. Using extant optical and infra-red photometry we constructed a preliminary photometric membership catalogue, consisting of 2230 dwarf and turn-off stars. We selected 1060 of these for observation with the AAOmega spectrograph at the 3.9m Anglo-Australian Telescope and 391 stars for observations with the Hydra-South spectrograph at the 4m Victor Blanco Telescope, obtaining spectroscopic observations over a decade for 145 stars. We measured radial velocities for our targets through cross-correlation with model spectra and standard stars, and supplemented them with radial velocities for 433 additional stars from the literature. We also measured logg, Teff, and [Fe/H] from the AAOmega spectra. The radial velocity distribution emerging from the observations is centred at 5.43+/-0.04km/s and has a width (standard deviation) of 1.46km/s. Together with proper motions from Gaia DR2 we find 660 exclusive members, of which five are likely binary members. The members are distributed across the whole cluster sequence, from giant stars to M dwarfs, making NGC~3532 one of the richest Galactic open clusters known to date, on par with the Pleiades. From further spectroscopic analysis of 153 dwarf members we find the metallicity to be marginally sub-solar, with [Fe/H]=-0.07+/-0.10. We confirm the extremely low reddening of the cluster, E_B-V_=0.034+/-0.012mag, despite its location near the Galactic plane. Exploiting trigonometric parallax measurements from Gaia DR2 we find a distance of 484^+35^_-30_pc [(m-M)_0_=8.42+/-0.14mag]. Based on the membership we provide an empirical cluster sequence in multiple photometric passbands. A comparison of the photometry of the measured cluster members with several recent model isochrones enables us to confirm the 300Myr cluster age. However, all of the models evince departures from the cluster sequence in particular regions, especially in the lower mass range.
- ID:
- ivo://CDS.VizieR/J/A+A/420/183
- Title:
- Spectroscopic survey in solar neighborhood
- Short Name:
- J/A+A/420/183
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report the results of a high-resolution spectroscopic survey of all the stars more luminous than M_V_=6.5mag within 14.5pc from the Sun. The Hipparcos catalog's completeness limits guarantee that our survey is comprehensive and free from some of the selection effects in other samples of nearby stars. The resulting spectroscopic database, which we have made publicly available, includes spectra for 118 stars obtained with a resolving power of R~50000, continuous spectral coverage between ~362-921nm, and typical signal-to-noise ratios in the range 150-600. We derive stellar parameters and perform a preliminary abundance and kinematic analysis of the F-G-K stars in the sample. The inferred metallicity ([Fe/H]) distribution is centered at about -0.1dex, and shows a standard deviation of 0.2dex.
