- ID:
- ivo://CDS.VizieR/VIII/57
- Title:
- Fluxes of Faint Radio Sources at 2.7/4.75 GHz
- Short Name:
- VIII/57
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This table is a compilation of revised 4.75 GHz and 2.695 GHz flux densities and corresponding spectral indices at epoch 1986.2 of a catalog of 239 sources, which has previously been published by Forkert and Altschuler, (1987A&AS...70...77F). It comprises 209 sources (marked 'A'), forming a complete, flux density limited sample above 50 mJy at 4.76 GHz in 1981.9 (Altschuler, 1986A&AS...65..267A), and 30 sources (marked 'a') below this limit, but with 5.0 GHz flux densities from 1971.0 (Davis, 1971AJ.....76..980D). The catalogue covers a narrow strip of the sky around declination of 33 degrees. The flux densities were calibrated with 3C286 on the scale of Kellermann, Pauliny-Toth and Williams (1969ApJ...157....1K). After publication of the catalog a statistical analysis for flux density variability in the data has been performed (Forkert, 1990), using 6cm flux density measurements of Davis (1971AJ.....76..980D) and Altschuler (1986A&AS...65..267A) and the 2.695 GHz flux densities of Pauliny-Toth et al. (1974A&A....35..421P), the details and results of which are going to be published elsewhere (Altschuler & Forkert, in preparation). For the purposes of this analysis it has become necessary to obtain more individual error estimates of the 1986.2 data, not dominated by the effect of overall scale errors. This revision for some of the sources also led to slightly different flux densities from those previously published. The variability study proved the flux density errors to represent the individual 1-sigma uncertainties, WITHOUT the effect of overall scale errors. From the aforementioned comparison with other measurements scale errors of ~1% at 2.695 GHz and ~3% at 4.75 GHz seem likely.
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Search Results
- ID:
- ivo://CDS.VizieR/J/ApJ/812/39
- Title:
- Fluxes of NGG7793 & NGC4945 with GMOS-S
- Short Name:
- J/ApJ/812/39
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Gas-phase abundances in HII regions of two spiral galaxies, NGC7793 and NGC4945, have been studied to determine their radial metallicity gradients. We used the strong-line method to derive oxygen abundances from spectra acquired with GMOS-S, the multi-object spectrograph on the 8m Gemini South telescope. We found that NGC7793 has a well-defined gas-phase radial oxygen gradient of -0.321+/-0.112dexR_25_^-1^ (or -0.054+/-0.019dex/kpc) in the galactocentric range 0.17<R_G_/R_25_<0.82, not dissimilar from gradients calculated with direct abundance methods in galaxies of similar mass and morphology. We also determined a shallow radial oxygen gradient in NGC 4945, -0.253+/-0.149dexR_25_^-1^ (or -0.019+/-0.011dex/kpc) for 0.04<R_G_/R_25_<0.51, where the larger relative uncertainty derives mostly from the larger inclination of this galaxy. NGC 7793 and NGC 4945 have been selected for this study because they are similar, in mass and morphology, to M33 and the Milky Way, respectively. Since at zeroth order we expect the radial metallicity gradients to depend on mass and galaxy type, we compared our galaxies in the framework of radial metallicity models best suited for M33 and the Galaxy. We found a good agreement between M33 and NGC7793, pointing toward similar evolution for the two galaxies. We notice instead differences between NGC 4945 and the radial metallicity gradient model that best fits the Milky Way. We found that these differences are likely related to the presence of an active galactic nucleus combined with a bar in the central regions of NGC 4945, and to its interacting environment.
- ID:
- ivo://CDS.VizieR/J/ApJ/864/71
- Title:
- Fluxes & physical param. of blended YSOs
- Short Name:
- J/ApJ/864/71
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Despite significant evidence suggesting that intermediate- and high-mass stars form in clustered environments, how stars form when the available resources are shared is still not well understood. A related question is whether the initial mass function (IMF) is in fact universal across galactic environments, or whether it is an average of IMFs that differ, for example, in massive versus low-mass molecular clouds. One of the long-standing problems in resolving these questions and in the study of young clusters is observational: how to accurately combine multiwavelength data sets obtained using telescopes with different spatial resolutions. The resulting confusion hinders our ability to fully characterize clustered star formation. Here we present a new method that uses Bayesian inference to fit the blended spectral energy distributions and images of individual young stellar objects (YSOs) in confused clusters. We apply this method to the infrared photometry of a sample comprising 70 Spitzer-selected, low-mass (M_cl_<100M_{sun}_) young clusters in the galactic plane, and we use the derived physical parameters to investigate how the distribution of YSO masses within each cluster relates to the total mass of the cluster. We find that for low-mass clusters this distribution is indistinguishable from a randomly sampled Kroupa IMF for this range of cluster masses. Therefore, any effects of self-regulated star formation that affect the IMF sampling are likely to play a role only at larger cluster masses. Our results are also compatible with smoothed particle hydrodynamics models that predict a dynamical termination of the accretion in protostars, with massive stars undergoing this stopping at later times in their evolution.
- ID:
- ivo://CDS.VizieR/J/ApJ/708/1760
- Title:
- Flux estimations of faint X-ray sources
- Short Name:
- J/ApJ/708/1760
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- X-ray sources with very few counts can be identified with low-noise X-ray detectors such as the Advanced CCD Imaging Spectrometer on board the Chandra X-ray Observatory. These sources are often too faint for parametric spectral modeling using well-established methods such as fitting with XSPEC. We discuss the estimation of apparent and intrinsic broadband X-ray fluxes and soft X-ray absorption from gas along the line of sight to these sources, using nonparametric methods. Apparent flux is estimated from the ratio of the source count rate to the instrumental effective area averaged over the chosen band. Absorption, intrinsic flux, and errors on these quantities are estimated from comparison of source photometric quantities with those of high signal-to-noise spectra that were simulated using spectral models characteristic of the class of astrophysical sources under study. The concept of this method is similar to the long-standing use of color-magnitude diagrams in optical and infrared astronomy, with X-ray median energy replacing color index and X-ray source counts replacing magnitude. Our nonparametric method is tested against the apparent spectra of ~2000 faint sources in the Chandra observation of the rich young stellar cluster in the M 17 HII region. We show that the intrinsic X-ray properties can be determined with little bias and reasonable accuracy using these observable photometric quantities without employing often uncertain and time-consuming methods of nonlinear parametric spectral modeling. Our method is calibrated for thermal spectra characteristic of stars in young stellar clusters, but recalibration should be possible for some other classes of faint X-ray sources such as extragalactic active galactic nuclei.
- ID:
- ivo://CDS.VizieR/J/A+A/642/A141
- Title:
- Flux-limited sample of HBL blazars, OUSXG
- Short Name:
- J/A+A/642/A141
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have analysed all the X-ray images centred on Gamma Ray Bursts generated by Swift over the last 15 years using automatic tools that do not require any expertise in X-ray astronomy, producing results in excellent agreement with previous findings. This work, besides presenting the largest medium-deep survey of the X-ray sky and a complete sample of blazars, wishes to be a step in the direction of achieving the ultimate goal of the Open Universe Initiative, that is to enable non expert people to fully benet of space science data, possibly extending the potential for scientific discovery, currently conned within a small number of highly specialised teams, to a much larger population. We have used the Swift deepsky Docker container encapsulated pipeline to build the largest existing flux-limited and unbiased sample of serendipitous X-ray sources. Swift deepsky runs on any laptop or desktop computer with a modern operating system. The tool automatically downloads the data and the calibration files from the archives, runs the official Swift analysis software and produces a number of results including images, the list of detected sources, X-ray fluxes, SED data, and spectral slope estimations. We used our source list to build the LogN-LogS of extra-galactic sources, which perfectly matches that estimated by other satellites. Combining our survey with multi-frequency data we selected a complete radio flux-density limited sample of High Energy Peaked (HBL) blazars. The LogN-LogS built with this data-set confirms that previous samples are incomplete below ~20mJy.
- ID:
- ivo://CDS.VizieR/J/AJ/159/100
- Title:
- Flux & RVs of the dwarf G9-40 with K2 & HPF
- Short Name:
- J/AJ/159/100
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We validate the discovery of a 2-Earth-radii sub-Neptune-sized planet around the nearby high-proper-motion M2.5 dwarf G9-40 (EPIC212048748), using high-precision, near-infrared (NIR) radial velocity (RV) observations with the Habitable-zone Planet Finder (HPF), precision diffuser-assisted ground-based photometry with a custom narrowband photometric filter, and adaptive optics imaging. At a distance of d=27.9pc, G9-40b is the second-closest transiting planet discovered by K2 to date. The planet's large transit depth (~3500ppm), combined with the proximity and brightness of the host star at NIR wavelengths (J=10, K=9.2), makes G9-40b one of the most favorable sub-Neptune-sized planets orbiting an M dwarf for transmission spectroscopy with James Webb Space Telescope, ARIEL, and the upcoming Extremely Large Telescopes. The star is relatively inactive with a rotation period of ~29days determined from the K2 photometry. To estimate spectroscopic stellar parameters, we describe our implementation of an empirical spectral-matching algorithm using the high-resolution NIR HPF spectra. Using this algorithm, we obtain an effective temperature of Teff=3404{+/-}73K and metallicity of [Fe/H]=-0.08{+/-}0.13. Our RVs, when coupled with the orbital parameters derived from the transit photometry, exclude planet masses above 11.7M{Earth} with 99.7% confidence assuming a circular orbit. From its radius, we predict a mass of M=5.0_-1.9_^+3.8^M_{Earth}_ and an RV semiamplitude of K=4.1_-1.6_^+3.1^m/s, making its mass measurable with current RV facilities. We urge further RV follow-up observations to precisely measure its mass, to enable precise transmission spectroscopic measurements in the future.
- ID:
- ivo://CDS.VizieR/J/ApJS/220/12
- Title:
- FMOS-COSMOS survey III. 0.7<z<2.5 galaxies
- Short Name:
- J/ApJS/220/12
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a spectroscopic survey of galaxies in the COSMOS field using the Fiber Multi-object Spectrograph (FMOS), a near-infrared instrument on the Subaru Telescope. Our survey is specifically designed to detect the H{alpha} emission line that falls within the H-band (1.6-1.8{mu}m) spectroscopic window from star-forming galaxies with 1.4<z<1.7 and M_stellar_>~10^10^M_{sun}_. With the high multiplex capability of FMOS, it is now feasible to construct samples of over 1000 galaxies having spectroscopic redshifts at epochs that were previously challenging. The high-resolution mode (R~2600) effectively separates H{alpha} and [NII]{lambda}6585, thus enabling studies of the gas-phase metallicity and photoionization state of the interstellar medium. The primary aim of our program is to establish how star formation depends on stellar mass and environment, both recognized as drivers of galaxy evolution at lower redshifts. In addition to the main galaxy sample, our target selection places priority on those detected in the far-infrared by Herschel/PACS to assess the level of obscured star formation and investigate, in detail, outliers from the star formation rate (SFR)--stellar mass relation. Galaxies with H{alpha} detections are followed up with FMOS observations at shorter wavelengths using the J-long (1.11-1.35{mu}m) grating to detect H{beta} and [OIII]{lambda}5008 which provides an assessment of the extinction required to measure SFRs not hampered by dust, and an indication of embedded active galactic nuclei. With 460 redshifts measured from 1153 spectra, we assess the performance of the instrument with respect to achieving our goals, discuss inherent biases in the sample, and detail the emission-line properties. Our higher-level data products, including catalogs and spectra, are available to the community.
6398. FOCAT-S Catalogue
- ID:
- ivo://CDS.VizieR/I/195
- Title:
- FOCAT-S Catalogue
- Short Name:
- I/195
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This is a new reduction of FOCAT-S photographic catalogue of southern stars. This reduction has to replace the preceding one. The differences from previous version are as follows: 1. The new version was sorted according right ascension of stars inside 10-degree declination zone; 2. New proper motions were calculated for all almost stars. New Astrographic Catalogue plate reduction was developed for this aim. The average rms of new FOCAT-S proper motions is 0.002 - 0.003 "/year; 3. The number of the Astrographic Catalogue star positions used for the proper motion calculation is added; 4. The magnitude (mag) and spectral type (Sp) columns were revised significantly: some errors were corrected; stars identified in C.S.I. catalogue have got Mag, Sp from this catalogue as it was in previous version. Other stars have got Mag, Sp from PPM-S catalogue. 5. The list of Durchmusterung star numbers was changed. Now it contains the Cape Photographic Durchmusterung (CPD) numbers for stars in [-90, -23] declination zones; Cordoba Durchmusterung (CoD) star numbers are used only if it was impossible to identify star in BD or CPD. Format of this column was changed also. 6. PPM catalogue star numbers were added.
- ID:
- ivo://CDS.VizieR/J/ApJ/891/3
- Title:
- Follow-up LCs of 2 Spitzer microlensing events
- Short Name:
- J/ApJ/891/3
- Date:
- 17 Jan 2022 00:32:54
- Publisher:
- CDS
- Description:
- We report the mass and distance measurements of two single-lens events from the 2017 Spitzer microlensing campaign. The ground-based observations yield the detection of finite-source effects, and the microlens parallaxes are derived from the joint analysis of ground-based observations and Spitzer observations. We find that the lens of OGLE-2017-BLG-1254 is a 0.60+/-0.03M_{sun}_ star with DLS=0.53+/-0.11kpc, where DLS is the distance between the lens and the source. The second event, OGLE-2017-BLG-1161, is subject to the known satellite parallax degeneracy, and thus is either a 0.51_-0.10_^+0.12^M_{sun}_ star with DLS=0.40+/-0.12kpc or a 0.38_-0.12_^+0.13^M_{sun} star with DLS=0.53+/-0.19kpc. Both of the lenses are therefore isolated stars in the Galactic bulge. By comparing the mass and distance distributions of the eight published Spitzer finite- source events with the expectations from a Galactic model, we find that the Spitzer sample is in agreement with the probability of finite-source effects occurring in single-lens events.
- ID:
- ivo://CDS.VizieR/J/ApJ/724/866
- Title:
- Follow-up observations of HAT-P-15
- Short Name:
- J/ApJ/724/866
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report the discovery of HAT-P-15b, a transiting extrasolar planet in the "period valley," a relatively sparsely populated period regime of the known extrasolar planets. The host star, GSC 2883-01687, is a G5 dwarf with V=12.16. It has a mass of 1.01+/-0.04M_{sun}_, radius of 1.08+/-0.04R_{sun}_, effective temperature 5568+/-90K, and metallicity [Fe/H]=+0.22+/-0.08. The planetary companion orbits the star with a period P=10.863502+/-0.000027 days, transit epoch T_c_=2454638.56019+/-0.00048(BJD), and transit duration 0.2285+/-0.0015days. It has a mass of 1.946+/-0.066M_J_ and radius of 1.072+/-0.043R_J_ yielding a mean density of 1.96+/-0.22g/cm^3^. At an age of 6.8^+2.5^_-1.6_Gyr, the planet is H/He-dominated and theoretical models require about 2% (10M_{earth}_) worth of heavy elements to reproduce its measured radius. With an estimated equilibrium temperature of ~820K during transit, and ~1000K at occultation, HAT-P-15b is a potential candidate to study moderately cool planetary atmospheres by transmission and occultation spectroscopy.