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- ID:
- ivo://CDS.VizieR/J/A+A/274/555
- Title:
- Asymmetry of FeI lines in solar spectrum
- Short Name:
- J/A+A/274/555
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- 75 FeI lines were studied from wide slit FTS spectra obtained at Kitt Peak at the center of the disk, near the limb ({mu}=0.2)
- ID:
- ivo://CDS.VizieR/J/ApJ/857/119
- Title:
- Asymmetry of oscillations in 43 Kepler stars
- Short Name:
- J/ApJ/857/119
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Oscillation properties are usually measured by fitting symmetric Lorentzian profiles to the power spectra of Sun-like stars. However, the line profiles of solar oscillations have been observed to be asymmetrical for the Sun. The physical origin of this line asymmetry is not fully understood; though, it should depend on the depth dependence of the source of wave excitation (convective turbulence) and details of the observable (velocity or intensity). For oscillations of the Sun, it has been shown that neglecting the asymmetry leads to systematic errors in the frequency determination. This could subsequently affect the results of seismic inferences of the solar internal structure. Using light curves from the Kepler spacecraft, we have measured mode asymmetries in 43 stars. We confirm that neglecting the asymmetry leads to systematic errors that can exceed the 1{sigma} confidence intervals for seismic observations longer than one year. Therefore, the application of an asymmetric Lorentzian profile should be favored to improve the accuracy of the internal stellar structure and stellar fundamental parameters. We also show that the asymmetry changes sign between cool Sun-like stars and hotter stars. This provides the best constraints to date on the location of the excitation sources across the Hertzsprung-Russel diagram.
- ID:
- ivo://CDS.VizieR/J/A+A/637/A20
- Title:
- AT 2019abn: multi-wavelength observations
- Short Name:
- J/A+A/637/A20
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- AT 2019abn was discovered in the nearby M51 galaxy by the Zwicky Transient Facility at more than two magnitudes and around three weeks prior to its optical peak. We aim to conduct a detailed photometric and spectroscopic follow-up campaign for AT 2019abn, with early discovery allowing for significant pre-maximum observations of an intermediate luminosity red transient (ILRT) for the first time. This work is based on the analysis of u'BVr'i'z'H photometry and low-resolution spectroscopy using the Liverpool Telescope, medium-resolution spectroscopy with the Gran Telescopio Canarias (GTC), and near-infrared imaging with the GTC and the Nordic Optical Telescope. We present the most detailed optical light curve of an ILRT to date, with multi-band photometry starting around three weeks before peak brightness. The transient peaked at an observed absolute magnitude of M_r_=-13.1, although it is subject to significant reddening from dust in M51, implying an intrinsic M_r_~-15.2. The initial light curve showed a linear, achromatic rise in magnitude before becoming bluer at peak. After peak brightness, the transient gradually cooled. This is reflected in our spectra, which at later times show absorption from such species as FeI, NiI and LiI. A spectrum taken around peak brightness shows narrow, low-velocity absorption lines, which we interpret as likely to originate from pre-existing circumstellar material. We conclude that while there are some peculiarities, such as the radius evolution, AT 2019abn fits in well overall with the ILRT class of objects and is the most luminous member of the class seen to date.
- ID:
- ivo://nasa.heasarc/actsouth
- Title:
- Atacama Cosmology Telescope (ACT) Extragalactic Southern Sources Catalog
- Short Name:
- ACTSOUTH
- Date:
- 14 Feb 2025
- Publisher:
- NASA/GSFC HEASARC
- Description:
- The ACTSOUTH catalog is a multi-frequency, multi-epoch catalog of extragalactic sources, based on 150, 220 and 280 GHz observations carried out in 2008, 2009 and 2010 using the Millimeter Bolometric Array Camera on the Atacama Cosmology Telescope. The catalog contains 695 sources, found in a sky area of ~600 square degrees. It is obtained by cross-matching sources found in 11 sub-catalogs, one for each season and frequency band. Also include are co-added data from ~150 and ~160 square degrees using 2 and 3 years of overlapping observations. The authors divide the sources into two populations, synchrotron and dusty emitters, based on their spectral behavior in the 150 - 220 GHz frequency range. They find 374 synchrotron sources and 321 dusty source candidates. Cross-matching with catalogs from radio to X-ray results in 264 synchrotron sources (71%) and 89 dusty sources (28%) with counterparts, suggesting that 232 dusty candidates are not in existing catalogs. This table was ingested by the HEASARC in November 2023 based upon the files downloaded from the LAMBDA archive at <a href="https://lambda.gsfc.nasa.gov/product/act/act_south_cat_get.html">https://lambda.gsfc.nasa.gov/product/act/act_south_cat_get.html</a>. This is a service provided by NASA HEASARC .
- ID:
- ivo://nasa.heasarc/actszclust
- Title:
- Atacama Cosmology Telescope DR5 Sunyaev-Zeldovich Cluster Catalog
- Short Name:
- ACTSZCLUST
- Date:
- 14 Feb 2025
- Publisher:
- NASA/GSFC HEASARC
- Description:
- The catalog of 4195 optically confirmed Sunyaev-Zel'dovich (SZ) selected galaxy clusters were detected with signal-to-noise > 4 in 13,211 deg<sup>2</sup> of sky surveyed by the Atacama Cosmology Telescope (ACT). Cluster candidates were selected by applying a multi-frequency matched filter to 98- and 150-GHz maps constructed from ACT observations obtained from 2008-2018 and confirmed using deep, wide-area optical surveys. The clusters span the redshift range 0.04 < z < 1.91 (median z = 0.52). The catalog contains 222 z > 1 clusters, and a total of 868 systems are new discoveries. Assuming an SZ-signal vs. mass scaling relation calibrated from X-ray observations, the sample has a 90% completeness mass limit of M<sub>500c</sub> > 3.8 x 10<sup>14</sup>M<sub>sol</sub>, evaluated at z=0.5, for clusters detected at signal-to-noise ratio > 5 in maps filtered at an angular scale of 2.40. The survey has a large overlap with deep optical weak-lensing surveys that are being used to calibrate the SZ-signal mass-scaling relation, such as the Dark Energy Survey (4566 deg<sup>2</sup>), the Hyper Suprime-Cam Subaru Strategic Program (469 deg<sup>2</sup>), and the Kilo Degree Survey (825 deg<sup>2</sup>). This HEASARC database table was ingested in February 2021. It contains the ACT DR5 SZ cluster catalog obtained from the LAMDBA website (<a href="https://lambda.gsfc.nasa.gov/product/act/actpol_dr5_szcluster_catalog_info.cfm#catalog">https://lambda.gsfc.nasa.gov/product/act/actpol_dr5_szcluster_catalog_info.cfm#catalog</a>). This is a service provided by NASA HEASARC .
- ID:
- ivo://nasa.heasarc/actssrcat
- Title:
- Atacama Cosmology Telescope 2008 Southern Survey 148/218 GHz Source Catalog
- Short Name:
- ACTSSRCAT
- Date:
- 14 Feb 2025
- Publisher:
- NASA/GSFC HEASARC
- Description:
- This table contains a catalog of 191 extragalactic sources detected by the Atacama Cosmology Telescope (ACT) at 148 and/or 218 GHz in the 2008 Southern survey. Flux densities span 14 -1700 mJy, and the authors use source spectral indices derived using ACT-only data to divide their sources into two subpopulations: 167 radio galaxies powered by central active galactic nuclei (AGN) and 24 dusty star-forming galaxies (DSFGs). They cross-identify 97% of their sources (166 of the AGN and 19 of the DSFGs) with those in currently available catalogs. When combined with flux densities from the Australia Telescope 20-GHz survey and follow-up observations with the Australia Telescope Compact Array, the synchrotron-dominated population is seen to exhibit a steepening of the slope of the spectral energy distribution from 20 to 148 GHz, with the trend continuing to 218 GHz. The ACT dust-dominated source population has a median spectral index, alpha<sub>148-218GHz</sub>, of 3.7<sup>+0.62</sup><sub>-0.86</sub>, and includes both local galaxies and sources with redshift around 6. Dusty sources with no counterpart in existing catalogs likely belong to a recently discovered subpopulation of DSFGs lensed by foreground galaxies or galaxy groups. The ACT experiment (Swetz et al., 2011, ApJS, 194, 41) is situated on the slopes of Cerro Toco in the Atacama Desert of Chile at an elevation of 5190m. ACT's latitude gives access to both the northern and southern celestial hemispheres. Observations occurred simultaneously in three frequency bands, at 148 GHz (2.0 mm), 218 GHz (1.4 mm) and 277 GHz (1.1 mm) with angular resolutions of roughly 1.4, 1.0 and 0.9 arcminutes, respectively. The ACT-detected source list contains 169 sources selected at 148 GHz with S/N > 5, spanning two decades in flux density, from 14 to 1700 mJy. The 218 GHz map independently yielded 133 sources with S/N > 5. The combination of these two independent source lists from which the present table was constructed gives a total count of 191 sources, with 110 galaxies detected with S/N > 5 at both frequencies. This table was created by the HEASARC in May 2015 based on <a href="https://cdsarc.cds.unistra.fr/ftp/cats/J/MNRAS/439/1556/">CDS Catalog J/MNRAS/439/1556/</a> file table4.dat. This is a service provided by NASA HEASARC .
- ID:
- ivo://nasa.heasarc/actegsrcat
- Title:
- Atacama Cosmology Telescope 2008 Survey 148-GHz Extragalactic Source Catalog
- Short Name:
- ACTEGSRCAT
- Date:
- 14 Feb 2025
- Publisher:
- NASA/GSFC HEASARC
- Description:
- This table contains a list of extragalactic radio sources detected in a 455 square-degree map of the southern sky made at a frequency of 148 GHz from the Atacama Cosmology Telescope (ACT) 2008 observing season. This catalog has 157 sources with flux densities spanning two orders of magnitude from 15 to 1500 mJy. Comparison to other catalogs shows that 98% of the ACT detections correspond to sources detected at lower radio frequencies. Three of the sources appear to be associated with the brightest cluster galaxies of low redshift X-ray selected galaxy clusters. Estimates of the radio to mm-wave spectral indices and differential counts of the sources further bolster the hypothesis that they are nearly all radio sources, and that their emission is not dominated by re-emission from warm dust. In a bright (>50 mJy) 148 GHz-selected sample with complete cross-identifications from the Australia Telescope 20-GHz survey, the authors of the study observe an average steepening of the spectra between 5, 20, and 148 GHz with median spectral indices of alpha<sub>5-20</sub> = -0.07 +/- 0.06, alpha<sub>20-148</sub> = -0.39 +/- 0.04, and alpha<sub>5-148</sub> = -0.20 +/- 0.03. When the measured spectral indices are taken into account, the 148-GHz differential source counts are consistent with previous measurements at 30 GHz in the context of a source count model dominated by flat spectrum radio sources. Extrapolating with an appropriately rescaled model for the radio source counts, the Poisson contribution to the spatial power spectrum from synchrotron-dominated sources with flux density less than 20 mJy is C<sub>Sync</sub> = (2.8 +/- 0.3) x 10<sup>-6</sup> microKelvin<sup>2</sup>. This table was created by the HEASARC in January 2011 based on an electronic version of Table A1 from the paper (the Point Source Catalog) which was obtained from the LAMBDA website at <a href="http://lambda.gsfc.nasa.gov/product/suborbit/act_prod_table.cfm">http://lambda.gsfc.nasa.gov/product/suborbit/act_prod_table.cfm</a> This is a service provided by NASA HEASARC .
1409. AT 2018bwo light curves
- ID:
- ivo://CDS.VizieR/J/A+A/653/A134
- Title:
- AT 2018bwo light curves
- Short Name:
- J/A+A/653/A134
- Date:
- 22 Feb 2022
- Publisher:
- CDS
- Description:
- Luminous red novae (LRNe) are astrophysical transients associated with the partial ejection of a binary system's common envelope (CE) shortly before its merger. Here we present the results of our photometric and spectroscopic follow-up campaign of AT 2018bwo (DLT 18x), a LRN discovered in NGC 45, and investigate its progenitor system using binary stellar-evolution models. The transient reached a peak magnitude of M_r_=-10.97+/-0.11 and maintained this brightness during its optical plateau of t_p_=41+/-5d ays. During this phase, it showed a rather stable photospheric temperature of ~3300K and a luminosity of ~10^40^erg/s. Although the luminosity and duration of AT 2018bwo is comparable to the LRNe V838 Mon and M31-2015LRN, its photosphere at early times appears larger and cooler, likely due to an extended mass-loss episode before the merger. Toward the end of the plateau, optical spectra showed a reddened continuum with strong molecular absorption bands. The IR spectrum at +103 days after discovery was comparable to that of an M8.5 II type star, analogous to an extended AGB star. The reprocessed emission by the cooling dust was also detected in the mid-infrared bands ~1.5 years after the outburst. Archival Spitzer and Hubble Space Telescope data taken 10-14yrs before the transient event suggest a progenitor star with T_prog_~6500K, R_prog_~100R_{sun}_, and L_prog_=2x10^4^L_{sun}_, and an upper limit for optically thin warm (1000K) dust mass of M_d_<10^-6^M_{sun}_. Using stellar binary-evolution models, we determined the properties of binary systems consistent with the progenitor parameter space. For AT 2018bwo, we infer a primary mass of 12-16M_{sun}_, which is 9-45% larger than the ~11M_{sun}_ obtained using single-star evolution models. The system, consistent with a yellow-supergiant primary, was likely in a stable mass-transfer regime with -2.4 <= log (M_dot/Msun /yr) <= -1.2 a decade before the main instability occurred. During the dynamical merger, the system would have ejected 0.15-0.5M_{sun}_ with a velocity of ~500km/s.
- ID:
- ivo://CDS.VizieR/J/A+A/445/465
- Title:
- ATCA 18.5 and 22GHz fluxes of Kuehr 5GHz sample
- Short Name:
- J/A+A/445/465
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We discuss our ATCA 18.5 and 22GHz flux density measurements of Southern extragalactic sources in the complete 5GHz sample of Kuehr et al. (1981, Cat. <VIII/5>). The high frequency (5-18.5GHz) spectral indices of steep-spectrum sources for which we have 18.5GHz data (66% of the complete sample) are systematically steeper than the low frequency (2.7-5GHz) ones, and there is evidence of an anti-correlation of high-frequency spectral index with luminosity. The completeness of 18.5GHz data is much higher (89%) for flat-spectrum sources (mostly quasars), which also exhibit a spectral steepening. Taking advantage of the almost complete redshift information on flat-spectrum quasars, we have estimated their 5GHz luminosity function in several redshift bins. The results confirm that their radio luminosity density peaks at z_peak about 2.5 but do not provide evidence for deviations from pure luminosity evolution as hinted at by other data sets. A comparison of our 22GHz flux densities with WMAP K-band data for flat-spectrum sources suggests that WMAP flux densities may be low by a median factor of about 1.2. The extrapolations of 5GHz counts and luminosity functions of flat-spectrum radio quasars using the observed distribution of the 5-18.5GHz spectral indices match those derived directly from WMAP data, indicating that the high frequency WMAP survey does not detect any large population of FSRQs with anomalous spectra.
