Search

Start Over Content Level Research
551. AFGL 2591-VLA 3 IRAM/NOEMA datacubes
ID:
ivo://CDS.VizieR/J/A+A/655/A84
Title:
AFGL 2591-VLA 3 IRAM/NOEMA datacubes
Short Name:
J/A+A/655/A84
Date:
10 Mar 2022 07:32:39
Publisher:
CDS
Description:
Increasing evidence suggests that, similar to their low-mass counterparts, high-mass stars form through a disk-mediated accretion process. At the same time, formation of high-mass stars still necessitates high accretion rates, and hence, high gas densities, which in turn can cause disks to become unstable against gravitational fragmentation. We study the kinematics and fragmentation of the disk around the high-mass star forming region AFGL 2591-VLA 3 which was hypothesized to be fragmenting based on the observations that show multiple outflow directions. We use a new set of high-resolution (0.19-arcsec) IRAM/NOEMA observations at 843 micron towards VLA 3 which allow us to resolve its disk, characterize the fragmentation, and study its kinematics. In addition to the 843 micron continuum emission, our spectral setup targets warm dense gas and outflow tracers such as HCN, HC_3_N and SO_2_, as well as vibrationally excited HCN lines. The high resolution continuum and line emission maps reveal multiple fragments with subsolar masses within the inner 1000AU of VLA 3. Furthermore, the velocity field of the inner disk observed at 843 micron shows a similar behavior to that of the larger scale velocity field studied in the CORE project at 1.37mm. We present the first observational evidence for disk fragmentation towards AFGL 2591-VLA 3, a source that was thought to be a single high-mass core. While the fragments themselves are low-mass, the rotation of the disk is dominated by the protostar with a mass of 10.3+/-1.8M_{sun}_. These data also show that NOEMA Band 4 can obtain the highest currently achievable spatial resolution at (sub-)mm wavelengths in observations of strong northern sources.
552. A final non-redundant catalogue for 7C 151-MHz survey
ID:
ivo://CDS.VizieR/VIII/84
Title:
A final non-redundant catalogue for 7C 151-MHz survey
Short Name:
VIII/84
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present a final unified catalogue for the 7C survey at 151 MHz with resolution 70x70cosec(dec) arcsec^2^. This has been constructed by amalgamating the existing catalogues derived from individual fields imaged at this resolution and eliminating redundancy in regions of mutual overlap. This is a non-trivial procedure because the flux in multiple-component sources may be fitted differently on alternative images, owing, for example, to differences in local noise and beam distortion. The final catalogue thus produced contains 43683 sources. Separate final catalogues have been published for the 7C Galactic Plane survey (7CG, see Cat. J/MNRAS/294/607) and the lower-resolution survey of the low-declination strip 9h<RA<16h, 20deg<Dec<35deg (Cat. J/MNRAS/282/779). The individual catalogues for about 40 of the regions contributing to the total have already been published, together with full details of the methodology, in MNRAS or A&AS: Lacy et al. 1995, MNRAS, 276, 614 (=1995MNRAS.276..614L) (#92 below) Visser et al. 1995, A&AS, 110, 419 (=1995A&AS..110..419V) (#93 below) Pooley et al. 1998, MNRAS, 298, 637 (=1998MNRAS.298..637P) (#94-96 below) Riley et al. 1999, MNRAS, 306, 31 (=1999MNRAS.306...31R) (# 1-33 below) and these data are also available via the MRAO website at http://www.mrao.cam.ac.uk/surveys/7C/ Individual catalogues for the remaining 58 regions by Riley et al. (#34-91 below) were released electronically via the MRAO website in November 2001. These include a re-analysis of data originally published in rather a different parametrization by McGilchrist et al. 1990, MNRAS, 246, 110 (=1990MNRAS.246..110M) The regions re-analyzed are those numbered #41,44,59,60,62 and 63 below and they supersede McGilchrist's 1990 publication. The RAxDec coverage, average rms noise, flux density of the faintest source listed and completeness limit for each of the individual regions contributing to the final catalogue are given in the table "regions.dat". 1-sigma errors on the listed source positions may be approximated by: RA..error(arcsec) = SQRT(1.0**2 + (32/SNR)**2) Dec.error(arcsec) = Kcosec(dec) x (RA error) where (approx) K= 1.0 around dec 70, increasing to 1.3 below dec 50, and 1-sigma errors on the listed flux densities may be approximated by: Error on S beam-fitted(Jy) = SQRT(0.03**2 + SNR**-2) x S(Jy) Error on SINT(Jy) = 1.5 x SQRT(0.03**2 + SNR**-2) x SINT(Jy) where SNR, S and SINT correspond to the columns denoted by those names in the byte-by-byte description below. For multi-component sources the SNR for the brightest component is used to estimate the SINT error. For further details of the surveys and data analysis procedures please refer to the published papers referenced at the head of this file and references therein.
553. A Finding List of Faint UV-Bright Stars
ID:
ivo://CDS.VizieR/II/212A
Title:
A Finding List of Faint UV-Bright Stars
Short Name:
II/212A
Date:
21 Oct 2021
Publisher:
CDS
Description:
195 UV-bright stars have been found on two-color 48-inch Schmidt plates centered on the galactic plane, and on one high-latitude plate. This catalog contains sources with (U-B) in the range U-B=0 to U-B=-1.5.
554. A Finding List of Faint UV-Bright Stars
ID:
ivo://CDS.VizieR/II/257A
Title:
A Finding List of Faint UV-Bright Stars
Short Name:
II/257A
Date:
21 Oct 2021
Publisher:
CDS
Description:
The survey lists the very blue objects found on the plates taken for the Sandage Two-Color Survey of the Galactic Plane obtained using the Palomar 48 inch Oschin Schmidt telescope. The sources range in U-B color from U-B~-0.1 to U-B~-1.0 and in magnitude from m_B_~10 to ~20.
555. A Finding List of Faint UV-Bright Stars
ID:
ivo://CDS.VizieR/II/231
Title:
A Finding List of Faint UV-Bright Stars
Short Name:
II/231
Date:
21 Oct 2021
Publisher:
CDS
Description:
The survey lists the very blue objects found on the plates taken for the Sandage Two-Color Survey of the Galactic Plane obtained using the Palomar 48 inch Oschin Schmidt telescope. The sources range in U-B color from U-B~-0.1 to U-B~-1.0 and in magnitude from m_B_~10 to ~20.
556. A first catalog of variable stars measured by ATLAS
ID:
ivo://CDS.VizieR/J/AJ/156/241
Title:
A first catalog of variable stars measured by ATLAS
Short Name:
J/AJ/156/241
Date:
21 Oct 2021
Publisher:
CDS
Description:
The Asteroid Terrestrial-impact Last Alert System (ATLAS) carries out its primary planetary defense mission by surveying about 13000 deg^2^ at least four times per night. The resulting data set is useful for the discovery of variable stars to a magnitude limit fainter than r~18, with amplitudes down to 0.02 mag for bright objects. Here, we present a Data Release One catalog of variable stars based on analyzing the light curves of 142 million stars that were measured at least 100 times in the first two years of ATLAS operations. Using a Lomb-Scargle periodogram and other variability metrics, we identify 4.7 million candidate variables. Through the Space Telescope Science Institute, we publicly release light curves for all of them, together with a vector of 169 classification features for each star. We do this at the level of unconfirmed candidate variables in order to provide the community with a large set of homogeneously analyzed photometry and to avoid pre-judging which types of objects others may find most interesting. We use machine learning to classify the candidates into 15 different broad categories based on light-curve morphology. About 10% (427000 stars) pass extensive tests designed to screen out spurious variability detections: we label these as "probable" variables. Of these, 214000 receive specific classifications as eclipsing binaries, pulsating, Mira-type, or sinusoidal variables: these are the "classified" variables. New discoveries among the probable variables number 315000, while 141000 of the classified variables are new, including about 10400 pulsating variables, 2060 Mira stars, and 74700 eclipsing binaries.
557. A framework for empirical galaxy phenomenology
ID:
ivo://CDS.VizieR/J/MNRAS/448/1430
Title:
A framework for empirical galaxy phenomenology
Short Name:
J/MNRAS/448/1430
Date:
21 Oct 2021
Publisher:
CDS
Description:
We develop a theoretical framework that extracts a deeper understanding of galaxy formation from empirically derived relations among galaxy properties by extending the main-sequence integration method for computing galaxy star formation histories. We properly account for scatter in the stellar mass-star formation rate relation and the evolving fraction of passive systems and find that the latter effect is almost solely responsible for the age distributions among z~0 galaxies with stellar masses above ~10^10^ M_{sun}_. However, while we qualitatively agree with the observed median stellar metallicity as a function of stellar mass, we attribute our inability to reproduce the distribution in detail largely to a combination of imperfect gas-phase metallicity and {alpha}/Fe ratio calibrations. Our formalism will benefit from new observational constraints and, in turn, improve interpretations of future data by providing self-consistent star formation histories for population synthesis modelling.
558. A frequency Comb calibrated solar atlas
ID:
ivo://CDS.VizieR/J/A+A/560/A61
Title:
A frequency Comb calibrated solar atlas
Short Name:
J/A+A/560/A61
Date:
21 Oct 2021
Publisher:
CDS
Description:
The solar spectrum is a primary reference for the study of physical processes in stars and their variation during activity cycles. High resolution spectra of the Sun are easily obtained from spatially selected regions of the solar disk, while those taken over the integrated disk are more problematic. However, a proxy can be obtained by using solar light reflected by small bodies of the solar system. We first apply the LFC solar spectrum to characterize the CCDs of the HARPS spectrograph. The comparison of the LFC and Th-Ar calibrated spectra reveals S-type distortions on each order along the whole spectral range with an amplitude of 40m/s. This confirms the pattern found by Wilken et al. (2010MNRAS.405L..16W) on a single order and extends the detection of the distortions to the whole analyzed region revealing that the precise shape varies with wavelength. A new data reduction is implemented to deal with CCD pixel inequalities to obtain a wavelength corrected solar spectrum. By using this spectrum we provide a new LFC calibrated solar atlas with 400 line positions in the range of 476-530, and 175 lines in the 534-585nm range corresponding to the LFC bandwidth. The new LFC atlas is consistent on average with that based on FTS solar spectra, but it improves the accuracy of individual lines by a significant factor reaching a mean value of 10m/s. The LFC-based solar line wavelengths are essentially free of major instrumental effects and provide a reference for absolute solar line positions at the date of Nov 2010, i.e. an epoch of low solar activity. We suggest that future LFC observations could be used to trace small radial velocity changes of the whole solar photospheric spectrum in connection with the solar cycle and for direct comparison with the predicted line positions of 3D radiative hydrodynamical models of the solar photosphere. The LFC calibrated solar atlas can be also used to verify the accuracy of ground or space spectrographs by means of the solar spectrum.
559. Afterglow light curve of GRB 090926A
ID:
ivo://CDS.VizieR/J/ApJ/720/862
Title:
Afterglow light curve of GRB 090926A
Short Name:
J/ApJ/720/862
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present VLT/FORS2 spectroscopy and Gamma-ray Optical/Near-Infrared Detector optical/near-IR photometry of the afterglow of the bright Fermi/LAT GRB 090926A. The spectrum shows prominent Lyman-{alpha} absorption with N_HI_=10^21.73+/-0.07^cm^-2^ and a multitude of metal lines at a common redshift of z=2.1062+/-0.0004, which we associate with the redshift of the gamma-ray burst (GRB). The metallicity derived from SII is log(Z/Z_{sun}_)~-1.9, one of the lowest values ever found in a GRB Damped Lyman-{alpha} (DLA) system. This confirms that the spread of metallicity in GRB-DLAs at z~2 is at least two orders of magnitude. We argue that this spread in metallicity does not require a similar range in abundances of the GRB progenitors, since the neutral interstellar medium probed by the DLA is expected to be at a significant distance from the explosion site. The hydrogen column density derived from the Swift/XRT afterglow spectrum (assuming log(Z/Z_{sun}_)~-1.9) is ~100 times higher than the N_HI_ obtained from the Lyman-{alpha} absorptions. This suggests either a large column density of ionized gas or a higher metallicity of the circum-burst medium compared to the gas traced by the DLA. We also discuss the afterglow light curve evolution and energetics. The absence of a clear jet-break like steeping until at least 21 days post-burst suggests a beaming-corrected energy release of E_{gamma}_>3.5x10^52^erg, indicating that GRB 090926A may have been one of the most energetic bursts ever detected.
560. Afterglows of short and long-duration GRBs
ID:
ivo://CDS.VizieR/J/ApJ/701/824
Title:
Afterglows of short and long-duration GRBs
Short Name:
J/ApJ/701/824
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present a comparative study of the observed properties of the optical and X-ray afterglows of short- and long-duration {gamma}-ray bursts (GRBs). Using a large sample of 37 short and 421 long GRBs, we find a strong correlation between the afterglow brightness measured after 11hr and the observed fluence of the prompt emission. Both the optical (R band) and X-ray flux densities (F_R_ and F_X_) scale with the {gamma}-ray fluence, F_{gamma}_. For bursts with a known redshift, a tight correlation exists between the afterglow flux densities at 11hr (rest frame) and the total isotropic {gamma}-ray energy, E_{gamma},ISO_: F_R,X_{prop.to}E_{gamma},ISO_^{alpha}^, with {alpha}~1.

Limit your search

more »

more »

more »

more »

more »

more »

more »