- ID:
- ivo://CDS.VizieR/J/AJ/157/231
- Title:
- MLSDSS-GaiaDR2 sample of M and L dwarfs
- Short Name:
- J/AJ/157/231
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a sample of 74216 M and L dwarfs constructed from two existing catalogs of cool dwarfs spectroscopically identified in the Sloan Digital Sky Survey (SDSS). We cross-matched the SDSS catalog with Gaia DR2 (Cat. I/345) to obtain parallaxes and proper motions and modified the quality cuts suggested by the Gaia Collaboration to make them suitable for late-M and L dwarfs. We also provide relations between Gaia colors and absolute magnitudes with spectral type and conclude that (G-G_RP_) has the tightest relation to spectral type for M and L dwarfs. In addition, we study magnetic activity as a function of position on the color-magnitude diagram, finding that H{alpha} magnetically active stars have, on average, redder colors and/or brighter magnitudes than inactive stars. This effect cannot be explained by youth alone and might indicate that active stars are magnetically inflated, binaries, and/or high metallicity. Moreover, we find that vertical velocity and vertical action dispersion are correlated with H{alpha} emission, confirming that these two parameters are age indicators. We also find that stars below the main sequence have high tangential velocity, which is consistent with a low metallicity and old population of stars that belong to the halo or thick disk.
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- ID:
- ivo://CDS.VizieR/J/A+A/453/635
- Title:
- Modelling the Galactic Interstellar Extinction
- Short Name:
- J/A+A/453/635
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Two Micron All Sky Survey (Cat. <II/246>), along with the Stellar Population Synthesis Model of the Galaxy, developed in Besancon, is used to calculate the extinction distribution along different lines of sight. The Galaxy model is used to provide the intrinsic colour of stars and their probable distances, so that the near infrared colour excess, and hence the extinction, may be calculated and its distance evaluated.
- ID:
- ivo://CDS.VizieR/J/ApJ/754/101
- Title:
- Monoceros Overdensity deep imaging with Subaru
- Short Name:
- J/ApJ/754/101
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We derive distance, density, and metallicity distribution of the stellar Monoceros Overdensity (MO) in the outer Milky Way, based on deep imaging with the Subaru Telescope. We applied color-magnitude diagram fitting techniques in three stripes at galactic longitudes, l~130{deg}, 150{deg}, 170{deg}, and galactic latitudes, +15{deg}<=b<=+25{deg}. The MO appears as a wall of stars at a heliocentric distance of ~10.1+/-0.5kpc across the observed longitude range with no distance change. The MO stars are more metal-rich ([Fe/H]~-1.0) than the nearby stars at the same latitude. These data are used to test three different models for the origin of the MO: a perturbed disk model, which predicts a significant drop in density adjacent to the MO that is not seen; a basic flared disk model, which can give a good match to the density profile but the MO metallicity implies the disk is too metal-rich to source the MO stars; and a tidal stream model, which, from the literature, brackets the distances and densities we derive for the MO, suggesting that a model can be found that would fully fit the MO data. Further data and modeling will be required to confirm or rule out the MO feature as a stream or as a flaring of the disk.
- ID:
- ivo://CDS.VizieR/J/A+A/453/923
- Title:
- Morphologies in the Cepheus Flare region
- Short Name:
- J/A+A/453/923
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- These tables contain the data of the cloud sample on which the study of the relationships between cloud morphology, optical and IR properties, and star formation is based. The sample was defined using the extinction map of the Cepheus Flare region covering ~256 square degrees created from the B band star counts of the USNO-A2.0 catalogue (Cat. <I/252>) with a typical resolution of 3 arcminutes on a 1.5 arcminute grid. Cloud definition and description was carried out using automatized methods. The main table lists the positions, peak extinctions, sizes, morphological parameters and classes, distances, mass estimations, parent cloud complexes, and the number of YSO candidates associated. An additional table with the names of the previously catalogued associated clouds and their references is also available.
- ID:
- ivo://CDS.VizieR/J/ApJ/886/40
- Title:
- Most luminous SPIRITS IR transients follow-up obs.
- Short Name:
- J/ApJ/886/40
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a systematic study of the most luminous (MIR [Vega magnitudes] brighter than -14) infrared (IR) transients discovered by the SPitzer InfraRed Intensive Transients Survey (SPIRITS) between 2014 and 2018 in nearby galaxies (D<35Mpc). The sample consists of nine events that span peak IR luminosities of M_[4.5],peak_ between -14 and -18.2, show IR colors between 0.2<([3.6]-[4.5])<3.0, and fade on timescales between 55d<t_fade_<480d. The two reddest events (A_V_>12) show multiple, luminous IR outbursts over several years and have directly detected, massive progenitors in archival imaging. With analyses of extensive, multiwavelength follow-up, we suggest the following possible classifications: five obscured core-collapse supernovae (CCSNe), two erupting massive stars, one luminous red nova, and one intermediate-luminosity red transient. We define a control sample of all optically discovered transients recovered in SPIRITS galaxies and satisfying the same selection criteria. The control sample consists of eight CCSNe and one Type Iax SN. We find that 7 of the 13 CCSNe in the SPIRITS sample have lower bounds on their extinction of 2<A_V_<8. We estimate a nominal fraction of CCSNe in nearby galaxies that are missed by optical surveys as high as 38.5_-21.9_^+26.0^% (90% confidence). This study suggests that a significant fraction of CCSNe may be heavily obscured by dust and therefore undercounted in the census of nearby CCSNe from optical searches.
- ID:
- ivo://CDS.VizieR/J/ApJ/786/117
- Title:
- M31 PHAT star clusters ages and masses
- Short Name:
- J/ApJ/786/117
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present ages and masses for 601 star clusters in M31 from the analysis of the six filter integrated light measurements from near-ultraviolet to near-infrared wavelengths, made as part of the Panchromatic Hubble Andromeda Treasury (PHAT). We derive the ages and masses using a probabilistic technique, which accounts for the effects of stochastic sampling of the stellar initial mass function. Tests on synthetic data show that this method, in conjunction with the exquisite sensitivity of the PHAT observations and their broad wavelength baseline, provides robust age and mass recovery for clusters ranging from ~10^2^ to 2x10^6^ M_{sun}_. We find that the cluster age distribution is consistent with being uniform over the past 100 Myr, which suggests a weak effect of cluster disruption within M31. The age distribution of older (>100 Myr) clusters falls toward old ages, consistent with a power-law decline of index -1, likely from a combination of fading and disruption of the clusters. We find that the mass distribution of the whole sample can be well described by a single power law with a spectral index of -1.9+/-0.1 over the range of 10^3^-3x10^5^ M_{sun}_. However, if we subdivide the sample by galactocentric radius, we find that the age distributions remain unchanged. However, the mass spectral index varies significantly, showing best-fit values between -2.2 and -1.8, with the shallower slope in the highest star formation intensity regions. We explore the robustness of our study to potential systematics and conclude that the cluster mass function may vary with respect to environment.
- ID:
- ivo://CDS.VizieR/J/ApJ/833/85
- Title:
- Multi-wavelength analysis of the MIR bubble N37
- Short Name:
- J/ApJ/833/85
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have performed a multi-wavelength analysis of a mid-infrared (MIR) bubble N37 and its surrounding environment. The selected 15'x15' area around the bubble contains two molecular clouds (N37 cloud; V_lsr_~37-43km/s, and C25.29+0.31; V_lsr_~43-48km/s) along the line of sight. A total of seven OB stars are identified toward the bubble N37 using photometric criteria, and two of them are spectroscopically confirmed as O9V and B0V stars. The spectro-photometric distances of these two sources confirm their physical association with the bubble. The O9V star appears to be the primary ionizing source of the region, which is also in agreement with the desired Lyman continuum flux analysis estimated from the 20cm data. The presence of the expanding HII region is revealed in the N37 cloud, which could be responsible for the MIR bubble. Using the ^13^CO line data and photometric data, several cold molecular condensations as well as clusters of young stellar objects (YSOs) are identified in the N37 cloud, revealing ongoing star formation (SF) activities. However, the analysis of ages of YSOs and the dynamical age of the HII region do not support the origin of SF due to the influence of OB stars. The position-velocity analysis of ^13^CO data reveals that two molecular clouds are interconnected by a bridge-like structure, favoring the onset of a cloud-cloud collision process. The SF activities (i.e., the formation of YSO clusters and OB stars) in the N37 cloud are possibly influenced by the cloud-cloud collision.
- ID:
- ivo://CDS.VizieR/J/AJ/144/101
- Title:
- Multiwavelength data of IRAS 20050+2720 young SFR
- Short Name:
- J/AJ/144/101
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- IRAS 20050+2720 is young star-forming region at a distance of 700pc without apparent high-mass stars. We present results of our multi-wavelength study of IRAS 20050+2720 which includes observations by Chandra and Spitzer, and Two Micron All Sky Survey and UBVRI photometry. In total, about 300 young stellar objects (YSOs) in different evolutionary stages are found. We characterize the distribution of YSOs in this region using a minimum spanning tree analysis. We newly identify a second cluster core, which consists mostly of class II objects, about 10' from the center of the cloud. YSOs of earlier evolutionary stages are more clustered than more evolved objects. The X-ray luminosity function (XLF) of IRAS 20050+2720 is roughly lognormal, but steeper than the XLF of the more massive Orion Nebula complex. IRAS 20050+2720 shows a lower N_H_/A_K_ ratio compared with the diffuse interstellar medium.
- ID:
- ivo://CDS.VizieR/J/ApJ/789/81
- Title:
- Multiwavelength survey of HII regions in NGC 300
- Short Name:
- J/ApJ/789/81
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results of a galaxy-wide study of molecular gas and star formation in a sample of 76 H II regions in the nearby spiral galaxy NGC 300. We have measured the molecular gas at 250pc scales using pointed CO(J=2-1) observations with the Atacama Pathfinder Experiment telescope. We detect CO in 42 of our targets, deriving molecular gas masses ranging from our sensitivity limit of ~10^5^M_{sun}_ to 7x10^5^M_{sun}_. We find a clear decline in the CO detection rate with galactocentric distance, which we attribute primarily to the decreasing radial metallicity gradient in NGC 300. We combine Galaxy Evolution Explorer far-ultraviolet, Spitzer 24{mu}m, and H{alpha} narrowband imaging to measure the star formation activity in our sample. We have developed a new direct modeling approach for computing star formation rates (SFRs) that utilizes these data and population synthesis models to derive the masses and ages of the young stellar clusters associated with each of our H II region targets. We find a characteristic gas depletion time of 230Myr at 250pc scales in NGC 300, more similar to the results obtained for Milky Way giant molecular clouds than the longer (>2Gyr) global depletion times derived for entire galaxies and kiloparsec-sized regions within them. This difference is partially due to the fact that our study accounts for only the gas and stars within the youngest star-forming regions. We also note a large scatter in the NGC 300 SFR-molecular gas mass scaling relation that is furthermore consistent with the Milky Way cloud results. This scatter likely represents real differences in giant molecular cloud physical properties such as the dense gas fraction.
- ID:
- ivo://CDS.VizieR/J/AJ/153/218
- Title:
- New IR photometric study of Ap and Am stars
- Short Name:
- J/AJ/153/218
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In this paper, 426 well known confirmed Ap and Am stars are photometrically studied in the infrared. The 2MASS, Wide-field Infrared Survey Explorer (WISE), and IRAS data are employed to make analyses. The results in this paper have shown that in the 1-3 {mu}m region over 90% Ap and Am stars have no or little infrared excesses, and infrared radiations in the near-infrared from these stars are probably dominated by the free-free emissions. It is also shown that in the 3-12 {mu}m region, the majority of Ap stars and Am stars have very similar behavior, i.e., in the W1-W2 (3.4-4.6 {mu}m) region, over half of Ap and Am stars have clear infrared excesses, which are possibly due to the binarity, the multiplicity, and/or the debris disk, but in the W2-W3 (4.6-12 {mu}m) region they have no or little infrared excess. In addition, in the 12-22 {mu}m region, some of Ap stars and Am stars show the infrared excesses and infrared radiations for these Ap and Am stars are probably due to the free-free emissions. In addition, it is seen that the probability of being the binarity, the multiplicity and/or the debris disk for Am stars is much higher than that for Ap stars. Furthermore, it can be seen that, in general, no relations can be found between infrared colors and spectral types either for Ap stars or for Am stars.
