GPM1 is the first version of the General Compiled Catalogue of Absolute Proper Motions for a sample of HIPPARCOS stars, derived with respect to galaxies within the plan called Catalogue of Faint Stars (KSZ, Deutch A.N., 1952IAUT....8..789D). The programme was proposed for several observatories of the former Soviet Union, China, Rumania and Spain. There are some resulting individual catalogues of absolute proper motions of stars compiled at five observatories (Kiev, Pulkovo, Moscow, Tashkent and Shanghai). The principal aim of the GPM1 construction was to provide absolute proper motions of stars to determine the rotation of the HIPPARCOS system. The GPM1 catalogue comprises absolute proper motions for 977 stars in 180 areas north of -25 degrees of declination. The mean square error is 8mas/yr on average. The standard errors differ from one star to another one depending on the number and quality of individual catalogues. They have been computed and presented for each star. For a single GPM1 field the absolute zero-point error of linking proper motions to the galaxies is 3mas/yr on average. The error of such a kind depends on the number and compactness of the galaxies available in each field. In addition to absolute proper motions and their mean errors, the catalogue gives the following data for each star: right ascension, declination, epoch for position, V-magnitude and number, copied from HIC. The stars were also identified with the objects of the Smithsonian Astrophysical Observatory Star Catalogue (SAO) list. Positions are given for equator and equinox J2000.0 on the system of FK5. They were presented to identify the GPM1 stars with those from other catalogues. The data file is sorted by J2000.0 right ascensions.
Current theories and models attempt to explain star formation globally, from core scales to giant molecular cloud scales. A multi-scale observational characterisation of an entire molecular complex is necessary to constrain them. We investigate star formation in G202.3+2.5, a ~10x3pc sub-region of the Monoceros OB1 cloud with a complex morphology harbouring interconnected filamentary structures. We aim to connect the evolution of cores and filaments in G202.3+2.5 with the global evolution of the cloud and to identify the engines of the cloud dynamics. In this first paper, the star formation activity is evaluated by surveying the distributions of dense cores and protostars, and their evolutionary state, as characterised using both infrared observations from the Herschel and WISE telescopes and molecular line observations with the IRAM 30-m telescope. We find ongoing star formation in the whole cloud, with a local peak in star formation activity around the centre of G202.3+2.5 where a chain of massive cores (10-50M_{sun}_) forms a massive ridge (>150M_{sun}_). All evolutionary stages from starless cores to Class II protostars are found in G202.3+2.5, including a possibly starless, large column density (8x10^22^cm^-2^), and massive (52M_{sun}_) core. All the core-scale observables examined in this paper point to an enhanced star formation activity centred on the junction between the three main branches of the ramified structure of G202.3+2.5. This suggests that the increased star-formation activity results from the convergence of these branches. To further investigate the origin of this enhancement, it is now necessary to extend the analysis to larger scales, in order to examine the relationship between cores, filaments and their environment. We address these points through the analysis of the dynamics of G202.3+2.5 in a joint paper.
Gigahertz peaked spectrum (GPS) radio sources are a class of extragalactic radio sources characterized by a spectral peak in the gigahertz domain. They are a mixed class of quasars and galaxies. A large proportion of the sources studied in the literature have only few data points in the radio domain, and the determination of variability and shape of the simultaneous spectra is inadequate. Sources currently included in the GPS source lists are very heterogeneous. We present the observational results from 12 observing campaigns (carried out between 2006 and 2010) at the RATAN-600 radio telescope to obtain the simultaneous radio spectra, which is valuable and necessary to derive genuine GPS sources from flat-spectrum radio sources caught in a flaring state when their spectra are temporarily inverted. The sample contains both quasar- and galaxy-type GPS (122 sources) identified in the literature.
Synthetic spectra and photometry for the GRAMS carbon-star set of radiative transfer models is provided in FITS form. Also included are various stellar and dust shell parameters related to the models. For each model, a 130-wavelength spectrum for the bare photosphere and one for the star+dust spectrum are available. The fluxes are in F_nu (Jansky) and are computed at the LMC distance (distance modulus = 18.5mag). Synthetic photometry is computed for 34 narrow- and broad-band filters which, in order, are: U, B, V, I, J, H, Ks, IRAC3_6, IRAC4_5, IRAC5_8, IRAC8_0, MIPS24, MIPS70, MIPS160, AKARIN2, AKARIN3, AKARIN4, AKARIS7, AKARIS9W, AKARIS11, AKARIL15, AKARIL18W, AKARIL24, WISEW1, WISEW2, WISEW3 and WISEW4 (see the footnotes in the article for more about these filters). Please read the FITS header for more information on the data.
Phebus instrument, a part of scientific equipment on board the Granat astrophysical Observatory, has the purpose to study cosmic gamma-ray bursts and solar flares in the range from 100keV to 100MeV. This is the final catalog of cosmic gamma-ray bursts (GRBs) observed in the PHEBUS experiment Granat orbiting astrophysical observatory. This catalogue contains information on 66 events recorded from December 1989 to May 199, 52 events recorded from June 1991 to December 199, 60 events recorded from January 1993 until September 1994, and 32 events recorded from October 1994 until December 1996. We provide the GRB light curves in the range 100keV - 1.6MeV, energy spectra and data on the total energy fluxes and energy fluxes at GRB luminosity peaks at energies above 100keV.
The PHEBUS database table is the Terekhov et al. (1994, 1995) and Tkachenko et al. (1998, 2002) Catalog of Cosmic Gamma-Ray Bursts Registered by the Phebus (or Phoebus) instrument on-board the GRANAT Observatory which operated from December 1989 to December 1996. One of the purposes of Phebus was to study cosmic gamma-ray bursts (GRBs) in the 100 keV to 100 MeV region of the spectrum. This catalog contains information on GRBs registered during the entire seven years of the mission, such as the energy fluxes observed at the GRB luminosity maxima and the time-integrated energy fluences in the energy range above 100 keV. The details of the Phebus detectors and other operational information, such as the criteria for burst detection, can be found in the Terekhov et al. and Tkachenko et al. papers which are listed in the References Section. The original version of this database table was created by the HEASARC in the late 1990s. Later updates were made in February 2002 and March 2003, based on the HEASARC's transcription of Tables 1 and 2 of Terekhov et al. (1994), Terekhov et al. (1995) and Tkachenko, A.Yu. et al. (1998), and of Table 1 of Tkachenko, A.Yu. et al. (2002). This is a service provided by NASA HEASARC .
We present the catalogue of gamma-ray bursts (GRB) observed with the WATCH all-sky monitor on board the GRANAT satellite during the period December 1989 to September 1994. The cosmic origin of 95 bursts comprising the catalogue is confirmed either by their localisation with WATCH or by their detection with other GRB experiments. For each burst its time history and information on its intensity in the two energy ranges 8-20keV and 20-60keV are presented. Most events show hardening of the energy spectrum near the burst peak. In part of the bursts an X-ray precursor or a tail is seen at 8-20keV. We have determined the celestial positions of the sources of 47 bursts. Their localisation regions (at 3-sigma confidence level) are equivalent in area to circles with radii ranging from 0.2 to 1.6deg. The burst sources appear isotropically distributed on the sky on large angular scales.
A large fraction of cool, low-mass stars exhibit brightness fluctuations that arise from a combination of convective granulation, acoustic oscillations, magnetic activity, and stellar rotation. Much of the short-timescale variability takes the form of stochastic noise, whose presence may limit the progress of extrasolar planet detection and characterization. In order to lay the groundwork for extracting useful information from these quasi-random signals, we focus on the origin of the granulation-driven component of the variability. We apply existing theoretical scaling relations to predict the star-integrated variability amplitudes for 508 stars with photometric light curves measured by the Kepler mission. We also derive an empirical correction factor that aims to account for the suppression of convection in F-dwarf stars with magnetic activity and shallow convection zones. So that we can make predictions of specific observational quantities, we performed Monte Carlo simulations of granulation light curves using a Lorentzian power spectrum. These simulations allowed us to reproduce the so-called flicker floor (i.e., a lower bound in the relationship between the full light-curve range and power in short-timescale fluctuations) that was found in the Kepler data. The Monte Carlo model also enabled us to convert the modeled fluctuation variance into a flicker amplitude directly comparable with observations. When the magnetic suppression factor described above is applied, the model reproduces the observed correlation between stellar surface gravity and flicker amplitude. Observationally validated models like these provide new and complementary evidence for a possible impact of magnetic activity on the properties of near-surface convection.
Granulations of red supergiants from ASAS-SN & iPTF
Short Name:
J/ApJ/898/24
Date:
07 Dec 2021 14:24:02
Publisher:
CDS
Description:
The mechanisms and characteristics of the irregular variations of red supergiants (RSGs) are studied based on the RSG samples in the Small Magellanic Cloud (SMC), Large Magellanic Cloud (LMC), and M31. With the time-series data from the All-Sky Automated Survey for SuperNovae and Intermediate Palomar Transient Factory survey, we use the continuous time autoregressive moving average model to estimate the variability features of the light curves and their power spectral density (PSD). The characteristic evolution timescale and amplitude of granulations are further derived from fitting the posterior PSD with the COR function, which is a Harvey-like granulation model. The consistency of theoretical predictions and results is checked to verify the correctness of the assumption that granulations on RSGs contribute to irregular variation. The relations between granulation and stellar parameters are obtained and compared with the results of red giant branch (RGB) stars and Betelgeuse. It is found that the relations are in agreement with predictions from basic physical process of granulation and fall close to the extrapolated relations of RGB stars. The granulations in most of the RSGs evolve at a timescale of several days to a year with a characteristic amplitude of 10-1000mmag. The results imply that the irregular variations of RSGs can be attributed to the evolution of granulations. When comparing the results from the SMC, LMC, and M31, the timescale and amplitude of granulation seem to increase with metallicity. The analytical relations of the granulation parameters with stellar parameters are derived for the RSG sample of each galaxy.
Gravitational arc candidates in the CFHTLS-Archive-Research Survey
CARS
Short Name:
carsarcs scs
Date:
15 Aug 2024 15:16:59
Publisher:
The GAVO DC team
Description:
Candidate gravitational arcs in the 37 deg^2 of
CFHTLS-Archive-Research Survey (CARS). The data include their
post-stamp images, astrometry, photometry (u*,g',r',i'), geometric
properties (length, length-to-width ratio, profile curvature, area),
and photometric redshifts. The arc candidates were selected booth with
an automatic arcfinder, based on a tailored image segmentation and a
color selection, and by visually inspecting the survey.