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51. A catalog of post-starburst QSOs from SDSS-DR7Q
ID:
ivo://CDS.VizieR/J/ApJ/857/27
Title:
A catalog of post-starburst QSOs from SDSS-DR7Q
Short Name:
J/ApJ/857/27
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present a catalog of nearby (z<=0.5) quasars with significant features of post-starburst stellar populations in their optical spectra: so-called post-starburst quasars, or PSQs. After carefully decomposing spectra from the Sloan Digital Sky Survey (SDSS) Data Release 7 (DR7) Quasar Catalog into quasar and host-galaxy components, we derive a sample of 208 PSQs. Their host-galaxy components have strong H{delta} absorption (EW>=6{AA}) indicating a significant contribution of an intermediate-aged stellar population formed in a burst of star formation within the past 1Gyr, which makes them potentially useful for studying the co-evolution of supermassive black holes and their host galaxies.
52. A catalogue of faint UV-excess objects
ID:
ivo://CDS.VizieR/J/MNRAS/243/1
Title:
A catalogue of faint UV-excess objects
Short Name:
J/MNRAS/243/1
Date:
21 Oct 2021
Publisher:
CDS
Description:
Spectra, positions, magnitudes and colours are presented for 1400 faint (B<~21mag) stellar objects identified in a complete, ultraviolet-excess (UVX) survey. The objects were selected from COSMOS machine measurements of UK Schmidt U and J plates and observed with the Fibre Optic Coupled Aperture Plate (FOCAP) system at the Anglo-Australian Telescope (AAT). In total, 420 QSOs were identified, of which nine belong to the broad absorption line (BAL) class of QSOs. A further 57 galaxies with narrow emission lines were found. Halo subdwarfs from the vast majority (~90 per cent) of the 824 galactic stars identified in this survey; the remaining galactic stars are comprised principally of hot white dwarfs (42 objects) and horizontal branch stars (nine objects). Updated versions of the QSO number-magnitude relation and luminosity function derived from this survey are also presented in this paper.
53. ACCESS. II. Shapley galaxies FUV-FIR photometry
ID:
ivo://CDS.VizieR/J/MNRAS/412/127
Title:
ACCESS. II. Shapley galaxies FUV-FIR photometry
Short Name:
J/MNRAS/412/127
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present panoramic Spitzer/MIPS mid- and far-infrared (MIR/FIR) and GALEX ultraviolet imaging of the most massive and dynamically active system in the local Universe, the Shapley supercluster at z=0.048, covering the five clusters that make up the supercluster core. We combine these data with existing spectroscopic data from 814 confirmed supercluster members to produce the first study of a local rich cluster including both ultraviolet and infrared luminosity functions (LFs).
54. Accretion history of massive stars
ID:
ivo://CDS.VizieR/J/MNRAS/496/3482
Title:
Accretion history of massive stars
Short Name:
J/MNRAS/496/3482
Date:
21 Oct 2021
Publisher:
CDS
Description:
The mass growth of protostars is a central element to the determination of fundamental stellar population properties such as the initial mass function. Constraining the accretion history of individual protostars is therefore an important aspect of star formation research. The goal of the study presented here is to determine whether high-mass (proto)stars gain their mass from a compact (<0.1pc) fixed-mass reservoir of gas, often referred to as dense cores, in which they are embedded, or whether the mass growth of high-mass stars is governed by the dynamical evolution of the parsec-scale clump that typically surrounds them. To achieve this goal, we performed a 350micron continuum mapping of 11 infrared dark clouds, along side some of their neighbouring clumps, with the ArTeMiS camera on APEX. By identifying about 200 compact ArTeMiS sources, and matching them with Herschel Hi-GAL 70micron sources, we have been able to produce mass vs. temperature diagrams. We compare the nature (i.e. starless or protostellar) and location of the ArTeMiS sources in these diagrams with modelled evolutionary tracks of both core-fed and clump-fed accretion scenarios. We argue that the latter provide a better agreement with the observed distribution of high-mass star-forming cores. However, a robust and definitive conclusion on the question of the accretion history of high-mass stars requires larger number statistics.
55. Accretion in disks in Cep OB2
ID:
ivo://CDS.VizieR/J/ApJ/710/597
Title:
Accretion in disks in Cep OB2
Short Name:
J/ApJ/710/597
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present accretion rates for a large number of solar-type stars in the Cep OB2 region, based on U-band observations. Our study comprises 95 members of the ~4Myr old cluster Tr 37 (including 20 "transition" objects (TOs)), as well as the only classical T Tauri star (CTTS) in the ~12Myr old cluster NGC 7160. The stars show different disk morphologies, with the majority of them having evolved and flattened disks. The typical accretion rates are about 1 order of magnitude lower than in regions aged 1-2Myr, and we find no strong correlation between disk morphology and accretion rates. Although half of the TOs are not accreting, the median accretion rates of normal CTTS and accreting "transition" disks are similar (~3x10^-9^ and 2x10^-9^M_{sun}_/yr, respectively). Comparison with other regions suggests that the TOs observed at different ages do not necessarily represent the same type of objects, which is consistent with the fact that the different processes that can lead to reduced IR excess/inner disk clearing (e.g., binarity, dust coagulation/settling, photoevaporation, giant planet formation) do not operate on the same timescales.
56. Accretion luminosities of young stars from Pf{beta}
ID:
ivo://CDS.VizieR/J/ApJ/769/21
Title:
Accretion luminosities of young stars from Pf{beta}
Short Name:
J/ApJ/769/21
Date:
21 Oct 2021
Publisher:
CDS
Description:
In this work, we introduce the use of HI Pfund {beta} (Pf{beta}; 4.6538{mu}m) as a tracer of mass accretion from protoplanetary disks onto young stars. Pf{beta} was serendipitously observed in NIRSPEC and CRIRES surveys of CO fundamental emission, amounting to a sample size of 120 young stars with detected Pf{beta} emission. Using a subsample of disks with previously measured accretion luminosities, we show that Pf{beta} line luminosity is well correlated with accretion luminosity over a range of at least three orders of magnitude. We use this correlation to derive accretion luminosities for all 120 targets, 65 of which are previously unreported in the literature. The conversion from accretion luminosity to accretion rate is limited by the availability of stellar mass and radius measurements; nevertheless, we also report accretion rates for 67 targets, 16 previously unmeasured. Our large sample size and our ability to probe high extinction values allow for relatively unbiased comparisons between different types of disks.
57. Accretion-rotation connection in NGC 2264
ID:
ivo://CDS.VizieR/J/A+A/599/A23
Title:
Accretion-rotation connection in NGC 2264
Short Name:
J/A+A/599/A23
Date:
21 Oct 2021
Publisher:
CDS
Description:
The low spin rates measured for solar-type stars at an age of a few Myr (~10% of the break-up velocity) indicate that some mechanism of angular momentum regulation must be at play in the early pre-main sequence. This may be associated with magnetospheric accretion and star-disk interaction, as suggested by observations that disk-bearing objects (CTTS) are slower rotators than diskless sources (WTTS) in young star clusters. We characterize the rotation properties for members of the star-forming region NGC 2264 (~3Myr) as a function of mass, and investigate the accretion-rotation connection at an age where about 50% of the stars have already lost their disks. We examined a sample of 500 cluster members (40% with disks, 60% without disks), distributed in mass between ~0.15 and 2M_{sun}_, whose photometric variations were monitored in the optical for 38 consecutive days with the CoRoT space observatory. Light curves were analyzed for periodicity using three different techniques: the Lomb-Scargle periodogram, the autocorrelation function and the string-length method. Periods were searched in the range between 0.17-days (i.e., 4h, twice the data sampling adopted) and 19-days (half the total time span). Period detections were confirmed using a variety of statistical tools (false alarm probability, Q-statistics), as well as visual inspection of the direct and phase-folded light curves.
58. AC114 galaxy cluster dynamical analysis
ID:
ivo://CDS.VizieR/J/MNRAS/452/3304
Title:
AC114 galaxy cluster dynamical analysis
Short Name:
J/MNRAS/452/3304
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present a dynamical analysis of the galaxy cluster AC114 based on a catalogue of 524 velocities. Of these, 169 (32 percent) are newly obtained at European Southern Observatory (Chile) with the Very Large Telescope and the VIsible MultiObject spectrograph. Data on individual galaxies are presented and the accuracy of the measured velocities is discussed. Dynamical properties of the cluster are derived. We obtain an improved mean redshift value z=0.31665+/-0.0008 and velocity dispersion {sigma}=1893^+73^_-82_km/s. A large velocity dispersion within the core radius and the shape of the infall pattern suggests that this part of the cluster is in a radial phase of relaxation with a very elongated radial filament spanning 12000km/s. A radial foreground structure is detected within the central 0.5h^-1^Mpc radius, recognizable as a redshift group at the same central redshift value. We analyse the colour distribution for this archetype Butcher-Oemler galaxy cluster and identify the separate red and blue galaxy sequences. The latter subset contains 44 percent of confirmed members of the cluster, reaching magnitudes as faint as R_f_=21.1 (1.0mag fainter than previous studies). We derive a mass M_200_=(4.3+/-0.7)x10^15^M_{sun}_h^-1^. In a subsequent paper, we will utilize the spectral data presented here to explore the mass-metallicity relation for this intermediate redshift cluster.
59. A Chandra X-ray observation of L1251B
ID:
ivo://CDS.VizieR/J/ApJ/694/425
Title:
A Chandra X-ray observation of L1251B
Short Name:
J/ApJ/694/425
Date:
21 Oct 2021
Publisher:
CDS
Description:
I report the results of a 60ks X-ray observation of the L1251 dark cloud in Cepheus, which was acquired with the ACIS-I camera on board the Chandra X-Ray Observatory. Forty-three compact X-ray sources were detected. The field of view was centered on the position of IRAS 22376+7455, an embedded Class 0/I protostar that is closely associated with the bright CO emission core, L1251B-Core E. A very intense impulsive X-ray flare was observed from a location within the formal error ellipse of the IRAS source and in close proximity (within <~1") to a thermal continuum radio source, VLA 3. Given their small spatial offsets, the radio, far-infrared, and X-ray objects appear to be identical and consequently the likely origin and driving source of high-velocity gas flows that are observed in L1251B.
60. ACIS-I observations of NGC 2264
ID:
ivo://CDS.VizieR/J/A+A/455/903
Title:
ACIS-I observations of NGC 2264
Short Name:
J/A+A/455/903
Date:
21 Oct 2021
Publisher:
CDS
Description:
This paper's goal is to improve the member census of the NGC 2264 star-forming region and study the origin of X-ray activity in young PMS stars. We analyze a deep, 100ks long, Chandra ACIS observation covering a 17'x17' field in NGC 2264. The preferential detection in X-rays of low-mass PMS stars gives strong indications of their membership. We study X-ray activity as a function of stellar and circumstellar characteristics by correlating the X-ray luminosities, temperatures, and absorptions with optical and near-infrared data from the literature.