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281. EUV estimates from CaII H&K activity
ID:
ivo://CDS.VizieR/J/A+A/644/A67
Title:
EUV estimates from CaII H&K activity
Short Name:
J/A+A/644/A67
Date:
21 Oct 2021
Publisher:
CDS
Description:
Atmospheric escape is an important factor shaping the exoplanet population and hence drives our understanding of planet formation. Atmospheric escape from giant planets is driven primarily by the stellar X-ray and extreme- ultraviolet (EUV) radiation. Furthermore, EUV and longer wavelength UV radiation power disequilibrium chemistry in the middle and upper atmosphere. Our understanding of atmospheric escape and chemistry, therefore, depends on our knowledge of the stellar UV fluxes. While the far-ultraviolet fluxes can be observed for some stars, most of the EUV range is unobservable due to the lack of a space telescope with EUV capabilities and, for the more distant stars, to interstellar medium absorption. Thus, it becomes essential to have indirect means for inferring EUV fluxes from features observable at other wavelengths. We present here analytic functions for predicting the EUV emission of F, G, K, and M-type stars from the log R'HK activity parameter that is commonly obtained from ground-based optical observations of the Ca II H&K lines. The scaling relations are based on a collection of about 100 nearby stars with published log R'HK and EUV flux values, where the latter are either direct measurements or inferences from high-quality far-ultraviolet (FUV) spectra. The scaling relations presented here return EUV flux values with an accuracy of about three, which is slightly lower than that of other similar methods based on FUV or X-ray measurements.
282. EVN Data Archive TAP service
ID:
ivo://jive.eu/tap
Title:
EVN Data Archive TAP service
Short Name:
EVN TAP
Date:
06 Sep 2024 07:00:06
Publisher:
Joint Institute for VLBI ERIC
Description:
The EVN Data Archive's TAP end point. The Table Access Protocol (TAP) lets you execute queries against our database tables, inspect various metadata, and upload your own data. It is thus the VO's premier way to access public data holdings. Tables exposed through this endpoint include: main from the evn schema, obscore from the ivoa schema, columns, groups, key_columns, keys, schemas, tables from the tap_schema schema.
283. Exoplanet hosts/field stars age consistency
ID:
ivo://CDS.VizieR/J/A+A/585/A5
Title:
Exoplanet hosts/field stars age consistency
Short Name:
J/A+A/585/A5
Date:
21 Oct 2021
Publisher:
CDS
Description:
Transiting planets around stars are discovered mostly through photometric surveys. Unlike radial velocity surveys, photometric surveys do not tend to target slow rotators, inactive or metal-rich stars. Nevertheless, we suspect that observational biases could also impact transiting-planet hosts. This paper aims to evaluate how selection effects reflect on the evolutionary stage of both a limited sample of transiting-planet host stars (TPH) and a wider sample of planet-hosting stars detected through radial velocity analysis. Then, thanks to uniform derivation of stellar ages, a homogeneous comparison between exoplanet hosts and field star age distributions is developed. Stellar parameters have been computed through our custom-developed isochrone placement algorithm, according to Padova evolutionary models. The notable aspects of our algorithm include the treatment of element diffusion, activity checks in terms of logR'_HK_ and vsini, and the evaluation of the stellar evolutionary speed in the Hertzsprung-Russel diagram in order to better constrain age. Working with TPH, the observational stellar mean density {rho}_*_ allows us to compute stellar luminosity even if the distance is not available, by combining {rho}_* with the spectroscopic logg. The median value of the TPH ages is ~5Gyr. Even if this sample is not very large, however the result is very similar to what we found for the sample of spectroscopic hosts, whose modal and median values are [3, 3.5)Gyr and ~4.8Gyr, respectively. Thus, these stellar samples suffer almost the same selection effects. An analysis of MS stars of the solar neighbourhood belonging to the same spectral types bring to an age distribution similar to the previous ones and centered around solar age value. Therefore, the age of our Sun is consistent with the age distribution of solar neighbourhood stars with spectral types from late F to early K, regardless of whether they harbour planets or not. We considered the possibility that our selected samples are older than the average disc population.
284. Extended stellar objects in galaxies
ID:
ivo://CDS.VizieR/J/A+A/547/A65
Title:
Extended stellar objects in galaxies
Short Name:
J/A+A/547/A65
Date:
21 Oct 2021
Publisher:
CDS
Description:
In the last decade, very extended old stellar clusters with masses in the range from a few 10^4^ to 10^8^M_{sun}_ and effective radii larger than 10pc have been found in various types of galaxies in different environments. Objects with masses comparable to normal globular clusters (GCs) are called extended clusters (ECs), while objects with masses in the dwarf galaxy regime are called ultra-compact dwarf galaxies (UCDs). The paper analyses the observational parameters total luminosity, M_V_, effective radius, r_eff_, and projected distance to the host galaxy, R_proj_, of all known ECs and UCDs and the dependence of these parameters on the type and the total luminosity of their host galaxy. We searched the available literature to compile a catalog of star clusters with effective radii larger than 10pc. As there is no clear distinction between ECs and UCDs, both types of objects will be called extended stellar objects - abbreviated "EOs" - in this paper. In total, we found 813 EOs of which 171 are associated with late-type galaxies and 642 EOs associated with early-type galaxies. EOs cover a luminosity range from about M_V_=-4 to -14mag. However, the vast majority of EOs brighter than M_V_=-10mag are associated with giant elliptical galaxies. At each magnitude extended objects are found with effective radii between 10pc and an upper size limit, which shows a clear trend: the more luminous the object the larger is the upper size limit. For EOs associated with early-and late-type galaxies, the EO luminosity functions peak at -6.40mag and -6.47mag, respectively, which is about one magnitude fainter than the peak of the GC luminosity function. EOs and GCs form a coherent structure in the r_eff_ vs. M_V_ parameter space, while there is a clear gap between EOs and early type dwarf galaxies. However, there is a small potential overlap at the high-mass end, where the most extended EOs are close to the parameters of some compact elliptical galaxies. We compare the EO sample with the numerical models of a previous paper and conclude that the parameters of the EO sample as a whole can be very well explained by a star cluster origin, where EOs are the results of merged star clusters of cluster complexes (CCs).
285. Extragalactic candidates in the VVV survey
ID:
ivo://CDS.VizieR/J/AJ/155/46
Title:
Extragalactic candidates in the VVV survey
Short Name:
J/AJ/155/46
Date:
21 Oct 2021
Publisher:
CDS
Description:
We search for extragalactic sources in the VISTA Variables in the Via Lactea survey that are hidden by the Galaxy. Herein, we describe our photometric procedure to find and characterize extragalactic objects using a combination of SExtractor and PSFEx. It was applied in two tiles of the survey: d010 and d115, without previous extragalactic IR detections, in order to obtain photometric parameters of the detected sources. The adopted criteria to define extragalactic candidates include CLASS_STAR<0.3; 1.0<R_1/2_<5.0 arcsec; 2.1<C<5; and {Phi}>0.002 and the colors: 0.5<(J-K_s_)<2.0 mag; 0.0<(J-H)<1.0 mag; 0.0<(H-K_s_)<2.0 mag and (J-H)+0.9(H-K_s_)>0.44 mag. We detected 345 and 185 extragalactic candidates in the d010 and d115 tiles, respectively. All of them were visually inspected and confirmed to be galaxies. In general, they are small and more circular objects, due to the near-IR sensitivity to select more compact objects with higher surface brightness. The procedure will be used to identify extragalactic objects in other tiles of the VVV disk, which will allow us to study the distribution of galaxies and filaments hidden by the Milky Way.
286. Extragalactic Database IV. Errors and misprints
ID:
ivo://CDS.VizieR/J/A+AS/91/371
Title:
Extragalactic Database IV. Errors and misprints
Short Name:
J/A+AS/91/371
Date:
21 Oct 2021
Publisher:
CDS
Description:
(no description available)
287. Extragalactic Radio Source Identifications
ID:
ivo://CDS.VizieR/VII/54
Title:
Extragalactic Radio Source Identifications
Short Name:
VII/54
Date:
21 Oct 2021
Publisher:
CDS
Description:
The catalog is a compilation of all published optical identifications of extragalactic radio sources. This machine-readable version is an updated and greatly expanded edition of the original published one; this version contains 14585 identifications and citations to 917 papers. The data file contains most commonly used source name, number in the 4C catalog Gower et al. (1967), and Pilkington and Scott (1965) if applicable, right ascension and declination (equinox B1950.0), magnitude estimate for the identification type of optical object, identification reference, alternate name for identified object (if known), confirmation or invalidation code and associated reference, finding chart existence (or nonexistence), redshift, and reference for the spectrum. A reference file contains the references ordered by number cited in the catalog and alphabetically by author. Completeness has been attempted for all papers published through the end of 1982. The present version contains fewer references than the 1974 version (which had 935) because certain numbers were unused in the previous edition and because certain references are no longer used in the 1983 version and were removed. The authors have prepared this final version and have discontinued future updates.
288. Extragalactic Reference Link Catalog (ERLcat)
ID:
ivo://CDS.VizieR/I/273A
Title:
Extragalactic Reference Link Catalog (ERLcat)
Short Name:
I/273A
Date:
21 Oct 2021
Publisher:
CDS
Description:
This is an astrometric catalog, providing positions of 89,422 stars in 398 selected fields of extragalactic reference frame sources. The stars are mainly in the 11 to 14 magnitude range. The average positional accuracy is about 50 mas per coordinate at the epoch of observation, which is between 1976.2 and 1991.9. The observations are based on photographic plates, taken with 2 telescopes which are: - the Hamburg Zone astrograph (in the Northern Hemisphere) - the USNO Twin astrograph at Black Birch (New Zealand)
289. Extremely Isolated Galaxies. II.
ID:
ivo://CDS.VizieR/J/MNRAS/469/347
Title:
Extremely Isolated Galaxies. II.
Short Name:
J/MNRAS/469/347
Date:
21 Oct 2021
Publisher:
CDS
Description:
We have selected a sample of 41 extremely isolated galaxies (EIGs) from the local Universe using both optical and HI Arecibo Legacy Fast ALFA survey redshifts. Narrow-band H{alpha} and wide-band imaging along with public data were used to derive star formation rates (SFRs), star formation histories and morphological classifications for the EIGs. We have found that the extreme isolation of the EIGs does not affect considerably their star formation compared to field galaxies. EIGs are typically 'blue cloud' galaxies that fit the 'main sequence of star-forming galaxies' and may show asymmetric star formation and strong compact star-forming regions. We discovered surprising environmental dependences of the HI content, M_HI_, and of the morphological type of EIGs; the most isolated galaxies (of subsample EIG-1) have lower M_HI_ on average (with 2.5{sigma} confidence) and a higher tendency to be early types (with 0.94 confidence) compared to the less isolated galaxies of subsample EIG-2. To the best of our knowledge, this is the first study that finds an effect in which an isolated sample shows a higher fraction of early types compared to a less isolated sample. Both early-type and late-type EIGs follow the same colour-to-M_*_, SFR-to-M_*_ (main sequence) and M_HI_-to-M_*_ relations. This indicates that the mechanisms and factors governing star formation, colour and the M_HI_-to-M_*_ relation are similar in early-type and late-type EIGs, and that the morphological type of EIGs is not governed by their M_HI_ content, colour or SFR.
290. FAI archives TAP service
ID:
ivo://fai.kz/tap
Title:
FAI archives TAP service
Short Name:
FAI NVO DC TAP
Date:
06 Mar 2025 00:24:23
Publisher:
Fesenkov Astrophysical Institute
Description:
The FAI archives's TAP end point. The Table Access Protocol (TAP) lets you execute queries against our database tables, inspect various metadata, and upload your own data. It is thus the VO's premier way to access public data holdings. Tables exposed through this endpoint include: main from the fai_agn schema, main from the geomagnetic_field schema, main from the grb_photometry schema, obscore from the ivoa schema, main from the maksutov_50_telescope schema, main from the neutrons schema, main from the pulsars schema, main from the schmidt_telescope_lc schema, main from the solar_flux schema, data from the spectra_agn_archive schema, columns, groups, key_columns, keys, schemas, tables from the tap_schema schema.

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