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3811. Maser and infrared studies of oxygen-rich AGB stars
ID:
ivo://CDS.VizieR/J/ApJ/794/81
Title:
Maser and infrared studies of oxygen-rich AGB stars
Short Name:
J/ApJ/794/81
Date:
21 Oct 2021
Publisher:
CDS
Description:
We explored an efficient method to identify evolved stars with oxygen-rich envelopes in the late asymptotic giant branch (AGB) or post-AGB phase of stellar evolution, which include a rare class of objects - the "water fountains (WF)." Our method considers the OH and H_2_O maser spectra, the near-infrared Q-parameters (these are color indices accounting for the effect of extinction), and far-infrared AKARI colors. Here we first present the results of a new survey on OH and H_2_O masers. There were 108 color-selected objects: 53 of them were observed in the three OH maser lines (1612, 1665, and 1667 MHz), with 24 detections (16 new for 1612 MHz); and 106 of them were observed in the H_2_O maser line (22 GHz), with 24 detections (12 new). We identify a new potential WF source, IRAS 19356+0754, with large velocity coverages of both OH and H_2_O maser emission. In addition, several objects with high-velocity OH maser emission are reported for the first time. The Q-parameters as well as the infrared [09]-[18] and [18]-[65] AKARI colors of the surveyed objects are then calculated. We suggest that these infrared properties are effective in isolating aspherical from spherical objects, but the morphology may not necessarily be related to the evolutionary status. Nonetheless, by considering altogether the maser and infrared properties, the efficiency of identifying oxygen-rich late/post-AGB stars could be improved.
3812. MASH Catalogues of Planetary Nebulae
ID:
ivo://CDS.VizieR/V/127A
Title:
MASH Catalogues of Planetary Nebulae
Short Name:
V/127A
Date:
21 Oct 2021
Publisher:
CDS
Description:
The Macquarie/AAO/Strasbourg H{alpha} Planetary Nebula Catalogue (MASH) contains 903 new true, likely and possible Galactic Planetary Nebulae (PNe) discovered from the AAO/UKST H{alpha} survey of the southern Galactic plane. The combination of depth, resolution, uniformity, and areal coverage of the H {alpha}survey has opened up an hitherto unexplored region of parameter space permitting the detection of this significant new PN sample. This catalogue includes also the spectra of the PNe as FITS files (in the "sp" subdirectory), and a gallery of images created as a combination of the H{alpha} and short red images of the survey. The second part, MASH-II (table mash2.dat) consists of over 300 true, likely and possible new Galactic PNe found after re-examination of the entire AAO/UKST H{alpha} survey of the Southern Galactic Plane in digital form. Over 240 of these new candidates were confirmed as bona fide PNe on the basis of spectroscopic observations. The spectra of this supplement will be available in the future.
3813. MASIV survey III. Optical identifications
ID:
ivo://CDS.VizieR/J/ApJ/767/14
Title:
MASIV survey III. Optical identifications
Short Name:
J/ApJ/767/14
Date:
21 Oct 2021
Publisher:
CDS
Description:
Intraday variability (IDV) of the radio emission from active galactic nuclei is now known to be predominantly due to interstellar scintillation (ISS). The MASIV (The Micro-Arcsecond Scintillation-Induced Variability) survey of 443 flat spectrum sources revealed that the IDV is related to the radio flux density and redshift. A study of the physical properties of these sources has been severely handicapped by the absence of reliable redshift measurements for many of these objects. This paper presents 79 new redshifts and a critical evaluation of 233 redshifts obtained from the literature. We classify spectroscopic identifications based on emission line properties, finding that 78% of the sources have broad emission lines and are mainly FSRQs. About 16% are weak lined objects, chiefly BL Lacs, and the remaining 6% are narrow line objects. The gross properties (redshift, spectroscopic class) of the MASIV sample are similar to those of other blazar surveys. However, the extreme compactness implied by ISS favors FSRQs and BL Lacs in the MASIV sample as these are the most compact object classes. We confirm that the level of IDV depends on the 5GHz flux density for all optical spectral types. We find that BL Lac objects tend to be more variable than broad line quasars. The level of ISS decreases substantially above a redshift of about two. The decrease is found to be generally consistent with ISS expected for beamed emission from a jet that is limited to a fixed maximum brightness temperature in the source rest frame.
3814. Mass accretion rates from HST in the ONC
ID:
ivo://CDS.VizieR/J/ApJ/755/154
Title:
Mass accretion rates from HST in the ONC
Short Name:
J/ApJ/755/154
Date:
21 Oct 2021
Publisher:
CDS
Description:
The present observational understanding of the evolution of the mass accretion rates (dM/dt_acc_) in pre-main-sequence stars is limited by the lack of accurate measurements of dM/dt_acc_ over homogeneous and large statistical samples of young stars. Such observational effort is needed to properly constrain the theory of star formation and disk evolution. Based on Hubble Space Telescope/WFPC2 observations, we present a study of dM/dt_acc_ for a sample of ~700 sources in the Orion Nebula Cluster, ranging from the hydrogen-burning limit to M*~2M_{sun}_. We derive dM/dt_acc_ from both the U-band excess and the H{alpha} luminosity (L_H{alpha}_), after determining empirically both the shape of the typical accretion spectrum across the Balmer jump and the relation between the accretion luminosity (L_acc_) and L_H{alpha}_, which is L_acc_/L_{sun}_=(1.31+/-0.03).L_H{alpha}/L_{sun}_+(2.63+/-0.13). Given our large statistical sample, we are able to accurately investigate relations between dM/dt_acc_ and the parameters of the central star such as mass and age.
3815. Mass accretion rates of PMS stars. VI. LH95 in LMC
ID:
ivo://CDS.VizieR/J/ApJ/875/51
Title:
Mass accretion rates of PMS stars. VI. LH95 in LMC
Short Name:
J/ApJ/875/51
Date:
21 Oct 2021
Publisher:
CDS
Description:
We report on the accretion properties of low-mass stars in the LH 95 association within the Large Magellanic Cloud. Using noncontemporaneous wideband optical and narrowband H{alpha} photometry obtained with the Hubble Space Telescope, we identify 245 low-mass pre-main-sequence (PMS) candidates showing H{alpha} excess emission above the 4{sigma} level. We derive their physical parameters, including effective temperatures, luminosities, masses (M_*_), ages, accretion luminosities, and mass accretion rates (dM/dt_acc_). We identify two different stellar populations: younger than ~8Myr with median dM/dt_acc_~5.4x10^-8^M_{sun}_/yr (and M_*_~0.15-1.8M_{sun}_) and older than ~8Myr with median dM/dt_acc_~4.8x10^-9^M_{sun}_/yr (and M_*_~0.6-1.2M_{sun}_). We find that the younger PMS candidates are assembled in groups around Be stars, while older PMS candidates are uniformly distributed within the region without evidence of clustering. We find that dM/dt_acc_ in LH 95 decreases with time more slowly than what is observed in Galactic star-forming regions (SFRs). This agrees with the recent interpretation, according to which higher metallicity limits the accretion process in both rate and duration due to higher radiation pressure. The dM/dt_acc_-M_*_ relationship shows different behavior at different ages, becoming progressively steeper at older ages, indicating that the effects of mass and age on dM/dt_acc_ cannot be treated independently. With the aim to identify reliable correlations between mass, age, and dM/dt_acc_, we used a multivariate linear regression fit between these parameters for our PMS candidates. The comparison between our results and those obtained in other SFRs of our Galaxy and the Magellanic Clouds confirms the importance of the metallicity for the study of the dM/dt_acc_ evolution in clusters with different environmental conditions.
3816. 2MASS All-Sky Catalog of Point Sources
ID:
ivo://CDS.VizieR/II/246
Title:
2MASS All-Sky Catalog of Point Sources
Short Name:
II/246
Date:
21 Oct 2021
Publisher:
CDS
Description:
The Two Micron All Sky Survey (2MASS) project is designed to close the gap between our current technical capability and our knowledge of the near-infrared sky. In addition to providing a context for the interpretation of results obtained at infrared and other wavelengths, 2MASS will provide direct answers to immediate questions on the large-scale structure of the Milky Way and the Local Universe. To achieve these goals, 2MASS is uniformly scanning the entire sky in three near-infrared bands to detect and characterize point sources brighter than about 1 mJy in each band, with signal-to-noise ratio (SNR) greater than 10, using a pixel size of 2.0". This will achieve an 80,000-fold improvement in sensitivity relative to earlier surveys. 2MASS uses two new, highly-automated 1.3-m telescopes, one at Mt. Hopkins, AZ, and one at CTIO, Chile. Each telescope is equipped with a three-channel camera, each channel consisting of a 256x256 array of HgCdTe detectors, capable of observing the sky simultaneously at J (1.25 {mu}m), H (1.65 {mu}m), and Ks (2.17 {mu}m), to a 3{sigma} limiting sensitivity of 17.1, 16.4 and 15.3mag in the three bands. The 2MASS arrays image the sky while the telescopes scan smoothly in declination at a rate of ~1' per second. The 2MASS data "tiles" are 6 deg. long in the declination direction and one camera frame (8.5') wide. The camera field-of-view shifts by ~1/6 of a frame in declination from frame-to-frame. The camera images each point on the sky six times for a total integration time of 7.8 s, with sub-pixel "dithering", which improves the ultimate spatial resolution of the final Atlas Images. The University of Massachusetts (UMass) is responsible for the overall management of the project, and for developing the infrared cameras and on-site computing systems at both facilities. The Infrared Processing and Analysis Center (IPAC) is responsible for all data processing through the Production Pipeline, and construction and distribution of the data products. The 2MASS project involves the participation of members of the Science Team from several different institutions. The 2MASS project is funding by the National Aeronautics and Space Administration (NASA) and the National Science Foundation (NSF).
3817. 2MASS Catalog Incremental Data Release
ID:
ivo://CDS.VizieR/II/241
Title:
2MASS Catalog Incremental Data Release
Short Name:
II/241
Date:
21 Oct 2021
Publisher:
CDS
Description:
The Two Micron All Sky Survey (2MASS) project is designed to close the gap between our current technical capability and our knowledge of the near-infrared sky. In addition to providing a context for the interpretation of results obtained at infrared and other wavelengths, 2MASS will provide direct answers to immediate questions on the large-scale structure of the Milky Way and the Local Universe. To achieve these goals, 2MASS is uniformly scanning the entire sky in three near-infrared bands to detect and characterize point sources brighter than about 1 mJy in each band, with signal-to-noise ratio (SNR) greater than 10, using a pixel size of 2.0". This will achieve an 80,000-fold improvement in sensitivity relative to earlier surveys. 2MASS uses two new, highly-automated 1.3-m telescopes, one at Mt. Hopkins, AZ, and one at CTIO, Chile. Each telescope is equipped with a three-channel camera, each channel consisting of a 256x256 array of HgCdTe detectors, capable of observing the sky simultaneously at J (1.25 {mu}m), H (1.65 {mu}m), and Ks (2.17 {mu}m), to a 3{sigma} limiting sensivity of 17.1, 16.4 and 1.3mag in thge three bands. The 2MASS arrays image the sky while the telescopes scan smoothly in declination at a rate of ~1' per second. The 2MASS data "tiles" are 6{deg} long in the declination direction and one camera frame (8.5') wide. The camera field-of-view shifts by ~1/6 of a frame in declination from frame-to-frame. The camera images each point on the sky six times for a total integration time of 7.8 s, with sub-pixel "dithering", which improves the ultimate spatial resolution of the final Atlas Images. The University of Massachusetts (UMass) is responsible for the overall management of the project, and for developing the infrared cameras and on-site computing systems at both facilities. The Infrared Processing and Analysis Center (IPAC) is responsible for all data processing through the Production Pipeline, and construction and distribution of the data products. The 2MASS project involves the participation of members of the Science Team from several different institutions. The 2MASS project is funding by the National Aeronautics and Space Administration (NASA) and the National Science Foundation (NSF).
3818. 2MASS colours of Magellanic cloud star clusters
ID:
ivo://CDS.VizieR/J/AJ/132/781
Title:
2MASS colours of Magellanic cloud star clusters
Short Name:
J/AJ/132/781
Date:
21 Oct 2021
Publisher:
CDS
Description:
The (rest-frame) near-IR domain contains important stellar population diagnostics and is often used to estimate masses of galaxies at low, as well as high, redshifts. However, many stellar population models are still relatively poorly calibrated in this part of the spectrum. To allow an improvement of this calibration we present a new database of integrated nearIR JHKs magnitudes for 75 star clusters in the Magellanic Clouds, using the Two Micron All Sky Survey (2MASS). The majority of the clusters in our sample have robust age and metallicity estimates from color-magnitude diagrams available in the literature, and populate a range of ages from 10Myr to 15Gyr and a range in [Fe/H] from -2.17 to +0.01dex. A comparison with matched star clusters in the 2MASS Extended Source Catalog (XSC) reveals that the XSC only provides a good fit to the unresolved component of the cluster stellar population. We also compare our results with the often-cited single-channel JHK photometry of Persson and coworkers (1983ApJ...266..105P).
3819. 2MASS counterparts for OH/IR stars
ID:
ivo://CDS.VizieR/J/AJ/127/501
Title:
2MASS counterparts for OH/IR stars
Short Name:
J/AJ/127/501
Date:
21 Oct 2021
Publisher:
CDS
Description:
The positions of the IRAS counterparts to the 420 OH/IR stars in the Arecibo sky (0{deg}<{delta}<+38{deg}) are usually accurate to better than 10". But every star has recently been observed by the Two Micron All Sky Survey (2MASS, <II/246>), which provides 0.2" quality positions, while those with |b|<=4.5{deg} have also been observed by the Midcourse Space Experiment (MSX, <V/114>), which provides ~2" quality positions. We use the MSX and/or IRAS coordinates to guide us to 2MASS counterparts for the 134 Arecibo OH/IR stars with images in the second release of the 2MASS Point Source Catalog. An unexpected by-product of having the J-H versus H-K_s_ plot generated from the 2MASS fluxes is the realization that most (~85%) of the redder OH/IR stars have detached circumstellar shells. We identify five objects that probably, by contrast, have "normal" shells, and we confirm the status of AU Vul as a protoplanetary nebula.
3820. Masses and photometry of 304 M31 old star clusters
ID:
ivo://CDS.VizieR/J/AJ/149/56
Title:
Masses and photometry of 304 M31 old star clusters
Short Name:
J/AJ/149/56
Date:
21 Oct 2021
Publisher:
CDS
Description:
This paper presents CCD multicolor photometry for 304 old star clusters in the nearby spiral galaxy M31, from which the photometry of 55 star clusters is first obtained. The observations were carried out as a part of the Beijing-Arizona-Taiwan-Connecticut Multicolor Sky Survey from 1995 February to 2008 March, using 15 intermediate-band filters covering 3000-10000{AA}. Detailed comparisons show that our photometry is in agreement with previous measurements. Based on the ages and metallicities from Caldwell et al. and the photometric measurements here, we estimated the clusters' masses by comparing their multicolor photometry with stellar population synthesis models. The results show that the sample clusters have masses between ~3x10^4^M_{sun}_ and ~10^7^M_{sun}_ with a peak of ~4x10^5^_M{sun}_. The masses here are in good agreement with those in previous studies. Combined with the masses of young star clusters of M31 from Wang et al., we find that the peak mass of the old clusters is 10 times that of young clusters.