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- ID:
- ivo://CDS.VizieR/J/A+A/578/A3
- Title:
- New survey of supergiants in the MCs
- Short Name:
- J/A+A/578/A3
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In this study, we conduct a pilot program aimed at the red supergiant population of the Magellanic Clouds. We intend to extend the current known sample to the unexplored low end of the brightness distribution of these stars, building a more representative dataset with which to extrapolate their behaviour to other Galactic and extra-galactic environments. We select candidates using only near infrared photometry, and with medium resolution multi-object spectroscopy, we perform spectral classification and derive their line-of-sight velocities, confirming the nature of the candidates and their membership to the clouds. Around two hundred new RSGs have been detected, hinting at a yet to be observed large population. Using near and mid infrared photometry we study the brightness distribution of these stars, the onset of mass-loss and the effect of dust in their atmospheres. Based on this sample, new a priori classification criteria are investigated, combining mid and near infrared photometry to improve the observational efficiency of similar programs as this.
- ID:
- ivo://CDS.VizieR/J/AJ/158/54
- Title:
- New Taurus members from stellar to planetary masses
- Short Name:
- J/AJ/158/54
- Date:
- 06 Dec 2021 11:31:43
- Publisher:
- CDS
- Description:
- We present a large sample of new members of the Taurus star-forming region that extend from stellar to planetary masses. To identify candidate members at substellar masses, we have used color-magnitude diagrams and proper motions measured with several wide-field optical and infrared (IR) surveys. At stellar masses, we have considered the candidate members that were found in a recent analysis of high-precision astrometry from the Gaia mission. Using new and archival spectra, we have measured spectral types and assessed membership for these 161 candidates, 79 of which are classified as new members. Our updated census of Taurus now contains 519 known members. According to Gaia data, this census should be nearly complete for spectral types earlier than M6-M7 at A_J_<1. For a large field encompassing ~72% of the known members, the census should be complete for K<15.7 at A_J_<1.5, which corresponds to ~5-13 M_Jup_ for ages of 1-10 Myr based on theoretical evolutionary models. Our survey has doubled the number of known members at >=M9 and has uncovered the faintest known member in M_K_, which should have a mass of ~3-10 M_Jup_ for ages of 1-10 Myr. We have used mid-IR photometry from the Spitzer Space Telescope and the Wide-field Infrared Survey Explorer to determine whether the new members exhibit excess emission that would indicate the presence of circumstellar disks. The updated disk fraction for Taurus is ~0.7 at =<M3.5 and ~0.4 at >M3.5.
1774. New ultracool subdwarfs
- ID:
- ivo://CDS.VizieR/J/A+A/598/A92
- Title:
- New ultracool subdwarfs
- Short Name:
- J/A+A/598/A92
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We developed an efficient method to search for late-type subdwarfs. We carried out a search cross-matching SDSS, 2MASS, and UKIDSS with VO tools. We considered different photometric and proper motion criteria for our selection. We identified 100 late-type subdwarf candidates. We obtained our own low-resolution optical spectra for 71 of our candidates and retrieved Sloan spectra for 30 of them (9 in common to the 71). We classified 92 candidates based on optical spectra. Our new discoveries include 49 subdwarfs, 25 extreme subdwarfs, six ultrasubdwarfs, one subdwarf/extreme subdwarf, and two dwarfs/subdwarfs. In addition, we discovered three early-L subdwarfs. We double the numbers of cool subdwarfs and derived a surface density of late-type subdwarfs.
- ID:
- ivo://CDS.VizieR/J/ApJ/725/842
- Title:
- New X-ray-selected SNRs detection with Chandra
- Short Name:
- J/ApJ/725/842
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present results from a study of the supernova remnant (SNR) population in a sample of six nearby galaxies (NGC 2403, NGC 3077, NGC 4214, NGC 4449, NGC 4395, and NGC 5204) based on Chandra archival data. We have detected 244 discrete X-ray sources down to a limiting flux of 10^-15^ erg/s/cm^2^. We identify 37 X-ray-selected thermal SNRs based on their X-ray colors or spectra, 30 of which are new discoveries. In many cases, the X-ray classification is confirmed based on counterparts with SNRs identified in other wavelengths. Three of the galaxies in our sample (NGC 4214, NGC 4395, and NGC 5204) are studied for the first time, resulting in the discovery of 13 thermal SNRs. We discuss the properties (luminosity, temperature, and density) of the X-ray-detected SNRs in the galaxies of our sample in order to address their dependence on their environment. We find that X-ray-selected SNRs in irregular galaxies appear to be more luminous than those in spirals. We attribute this to the lower metallicities and therefore more massive progenitor stars of irregular galaxies or the higher local densities of the interstellar medium. We also discuss the X-ray-selected SNR populations in the context of the star formation rate of their host galaxies. A comparison of the numbers of observed luminous X-ray-selected SNRs with those expected based on the luminosity functions of X-ray SNRs in the Magellanic Clouds and M33 suggest different luminosity distributions between the SNRs in spiral and irregular galaxies with the latter tending to have flatter distributions.
- ID:
- ivo://CDS.VizieR/J/AJ/156/76
- Title:
- New young stars and brown dwarfs in Upper Sco
- Short Name:
- J/AJ/156/76
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- To improve the census of the Upper Sco association (~11 Myr, ~145 pc), we have identified candidate members using parallaxes, proper motions, and color-magnitude diagrams from several wide-field imaging surveys and have obtained optical and infrared spectra of several hundred candidates to measure their spectral types and assess their membership. We also have performed spectroscopy on a smaller sample of previously known or suspected members to refine their spectral types and evidence of membership. We have classified 530 targets as members of Upper Sco, 377 of which lack previous spectroscopy. Our new compilation of all known members of the association contains 1631 objects. Although the census of Upper Sco has expanded significantly over the last decade, there remain hundreds of candidates that lack spectroscopy. The precise parallaxes and proper motions from the second data release of Gaia should extend down to substellar masses in Upper Sco, which will greatly facilitate the identification of the undiscovered members.
- ID:
- ivo://CDS.VizieR/J/A+A/537/A108
- Title:
- NGC 6822 AGB spectroscopic catalogue
- Short Name:
- J/A+A/537/A108
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We calibrate spectroscopically the C- versus (vs.) M-type asymptotic giant branch (AGB) star selection made using near-IR photometry, and investigate the spatial distribution of the C/M ratio in NGC 6822, based on low resolution spectroscopy and near-IR photometry.
- ID:
- ivo://CDS.VizieR/J/A+A/621/A83
- Title:
- NGC 1566 ALMA and Gemini-GMOS/IFU datacubes
- Short Name:
- J/A+A/621/A83
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Tracing nuclear inflows and outflows in AGNs, determining the mass of gas involved in them, and their impact on the host galaxy and nuclear black hole requires 3-D imaging studies of both the ionized and molecular gas. We map the distribution and kinematics of molecular and ionized gas in a sample of active galaxies to quantify the nuclear inflows and outflows. Here, we analyze the nuclear kinematics of NGC 1566 via ALMA observations of the CO J:2-1 emission at 24pc spatial and ~2.6km/s spectral resolution, and Gemini-GMOS/IFU observations of ionized gas emission lines and stellar absorption lines at similar spatial resolution, and 123km/s of intrinsic spectral resolution. The morphology and kinematics of stellar, molecular (CO), and ionized ([NII]) emission lines are compared to the expectations from rotation, outflows, and streaming inflows. While both ionized and molecular gas show rotation signatures, there are significant non-circular motions in the innermost 200pc and along spiral arms in the central kpc (CO). The nucleus shows a double-peaked CO profile (full width at zero intensity of 200km/s), and prominent (~80km/s) blue- and redshifted lobes are found along the minor axis in the inner arcseconds. Perturbations by the large-scale bar can qualitatively explain all features in the observed velocity field. We thus favor the presence of a molecular outflow in the disk with true velocities of ~180km/s in the nucleus and decelerating to 0 by ~72pc. The implied molecular outflow rate is 5.6M_{Sun}_/yr, with this gas accumulating in the nuclear 2" arms. The ionized gas kinematics support an interpretation of a similar but more spherical outflow in the inner 100pc, with no signs of deceleration. There is some evidence of streaming inflows of ~50km/s along specific spiral arms, and the estimated molecular mass inflow rate, ~0.1M_{Sun}_/yr, is significantly higher than the SMBH accretion rate (dM/dt=4.8x10^-5^M_{Sun}_/yr).
- ID:
- ivo://CDS.VizieR/J/A+A/582/A91
- Title:
- NGC 4418 ALMA mm-wave spectral scan
- Short Name:
- J/A+A/582/A91
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Extragalactic observations allow the study of molecular chemistry and excitation under physical conditions which may differ greatly from what found in the Milky Way. The compact, obscured nuclei (CON) of luminous infrared galaxies (LIRG) combine large molecular columns with intense infrared (IR), ultra-violet (UV) and X- radiation and represent ideal laboratories to study the chemistry of the interstellar medium (ISM) under extreme conditions. To obtain for the first time a multi-band spectral scan of a LIRG, in order to derive the molecular abundances and excitation, to be compared to other Galactic and extragalactic environments. We obtained an ALMA Cycle 0 spectral scan of the dusty LIRG NGC 4418, spanning a total of 70.7GHz in bands 3, 6, and 7. We use a combined local thermal equilibrium (LTE) and non-LTE (NLTE) fit of the spectrum in order to identify the molecular species and derive column densities and excitation temperatures. We derive molecular abundances and compare them with other Galactic and extragalactic sources by means of a principal component analysis.
- ID:
- ivo://CDS.VizieR/J/A+A/599/A9
- Title:
- NGC 4214 [CII] line profile
- Short Name:
- J/A+A/599/A9
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We used SOFIA/GREAT [CII] 158um observations as well as HI data from THINGS and CO(2-1) data from HERACLES to decompose the spectrally resolved [CII] line profiles in NGC4124 into components associated with neutral atomic and molecular gas. We infer gas masses traced by [CII] under different ISM conditions. We find that the molecular gas mass is dominated by CO-dark gas and that we can only assign 9 percent of [CII] intensity to the cold neutral medium.
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