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1151. Faint Stroemgren photometry
ID:
ivo://CDS.VizieR/J/AJ/104/1765
Title:
Faint Stroemgren photometry
Short Name:
J/AJ/104/1765
Date:
21 Oct 2021
Publisher:
CDS
Description:
We have initiated a faint photometric survey in the Stroemgren system covering ~1 square degree and including 1238 objects in order to develop samples which best probe the thick disk population. The catalog of observations are presented here. They were acquired without kinematic or metallicity biases and are complete to V=17.3-18.5, depending on the field, for 810 early to relatively late type (K0 V or G5 III) stars. Photometric metallicities were derived for 508 stars and indicate a metal-poor stellar population, consistent with a mixture of thick disk and halo stars. While the Stroemgren u-band was not part of the survey, follow-up u-band observations of 32 survey objects indicate that intermediate color survey stars (0.3<=b-y<=0.5) are main-sequence or slightly evolved stars, while redder survey stars (b-y>=0.5) are giants. The survey catalog is available in electronic form upon request.
1152. Faint UBVRI standard stars at +50{deg} declination
ID:
ivo://CDS.VizieR/J/AJ/152/91
Title:
Faint UBVRI standard stars at +50{deg} declination
Short Name:
J/AJ/152/91
Date:
21 Oct 2021
Publisher:
CDS
Description:
Precise and accurate CCD-based UBVRI photometry is presented for ~2000 stars distributed around the sky in a declination zone centered approximately at +50{deg}. Their photometry has been calibrated to the standard Johnson UBV and Kron-Cousins RI systems through observations of the UBVRI standard stars presented in the various works of Landolt. The magnitude and color range for these stars are 12<~V<~22 and -0.3<~(B-V)<~1.8, respectively. Each star averages 13 measures in each UBVRI filter from data taken on 41 different photometric nights obtained over a 21 month period. Hence, there now exists a network of faint UBVRI photometric standard stars centered on the declination zones {delta}=-50{deg}, 0{deg}, and +50{deg}.
1153. Faint UV standards from Swift, GALEX and SDSS
ID:
ivo://CDS.VizieR/J/ApJ/725/1215
Title:
Faint UV standards from Swift, GALEX and SDSS
Short Name:
J/ApJ/725/1215
Date:
21 Oct 2021
Publisher:
CDS
Description:
At present, the precision of deep ultraviolet photometry is somewhat limited by the dearth of faint ultraviolet standard stars. In an effort to improve this situation, we present a uniform catalog of 11 new faint (u~17) ultraviolet standard stars. High-precision photometry of these stars has been taken from the Sloan Digital Sky Survey and Galaxy Evolution Explorer archives and combined with new data from the Swift Ultraviolet Optical Telescope to provide precise photometric measures extending from the near-infrared to the far-ultraviolet. These stars were chosen because they are known to be hot (20000<T_eff_<50000K) DA white dwarfs with published Sloan spectra that should be photometrically stable. This careful selection allows us to compare the combined photometry and Sloan spectroscopy to models of pure hydrogen atmospheres to both constrain the underlying properties of the white dwarfs and test the ability of white dwarf models to predict the photometric measures.
1154. F- and G-type stars in solar neighbourhood
ID:
ivo://CDS.VizieR/J/MNRAS/360/1345
Title:
F- and G-type stars in solar neighbourhood
Short Name:
J/MNRAS/360/1345
Date:
21 Oct 2021
Publisher:
CDS
Description:
A new metallicity distribution and an age-metallicity relation are presented for 437 nearby F and G turn-off and sub-giant stars selected from radial velocity data of Nidever et al. (2002, Cat. J/ApJS/141/503). Photometric metallicities are derived from uvby-H{beta} photometry, and the stellar ages from the isochrones of Bergbusch & VandenBerg (2001ApJ...556..322B) as transformed to uvby photometry using the methods of Clem et al. (2004, Cat. J/AJ/127/1227).
1155. Fast-rotating nearby solar-type stars. I.
ID:
ivo://CDS.VizieR/J/A+A/384/491
Title:
Fast-rotating nearby solar-type stars. I.
Short Name:
J/A+A/384/491
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present the results of high-resolution spectroscopic and high-precision photometric observations on a sample of 129 late-F and G-type nearby stars selected on the basis of their large rotational velocity. Using also data from the Hipparcos satellite, CORAVEL and from the ROSAT satellite database, we infer spectral types, compute radial velocities, vsini, Li abundances and X-ray luminosities and investigate the single or binary nature of the sample stars. Such a careful analysis of our sample shows a large fraction of binaries (~62%) and of young single disk stars. In particular, at least 9 stars can be considered bona-fide PMS or ZAMS objects, and 30 stars are identified as SBs for the first time. Information on the presence of Ca II K emission and on optical variability is given for some of the stars of the sample. The photometry has been obtained at the European Southern Observatory (ESO-La silla, Chile) during several observing runs (19/11-03/12 1993, 24/11-04/12 1994, 15-28/01/1995 and 1-12/10/1995), by using the 50cm ESO telescope. The figures were published in paper II.
1156. FAUST sources in NGC 4038-39 and 6752 direction
ID:
ivo://CDS.VizieR/J/MNRAS/324/580
Title:
FAUST sources in NGC 4038-39 and 6752 direction
Short Name:
J/MNRAS/324/580
Date:
21 Oct 2021
Publisher:
CDS
Description:
Analysis of ultraviolet (UV) observations with the FAUST shuttle-borne telescope toward the Antennae and NGC 6752 celestial regions resulted in the detection of 46 and 221 candidate sources respectively, for a signal-to-noise ratio of 8. We discuss the source detection process and the identification of UV sources with optical counterparts. Using correlations with existing catalogues, we present reliable identifications for approximately 60 per cent of the sources. We find that most identified objects are B, A and F stars. The remaining identified objects are galaxies, a white dwarf in a binary system, and two K-type stars. Nearly all of the remaining unidentified objects have assigned optical counterparts but, lacking additional information, we give these only as best estimates. With help from new diagnostic diagrams, we suggest that these unclassified objects are main-sequence (or giant) stars within the local spiral arm or halo; or other hot evolved objects within the local spiral arm. We discuss the nature of the objects found and compare our results with those predicted from spectral and Galactic models.
1157. FAUST UV sources towards Ophiuchus
ID:
ivo://CDS.VizieR/J/MNRAS/332/441
Title:
FAUST UV sources towards Ophiuchus
Short Name:
J/MNRAS/332/441
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present results of an analysis of a UV image in the direction of Ophiuchus, obtained with the FAUST instrument. The image contains 228 UV sources. Most of these are identified as normal early-type stars through correlations with catalogued objects. For the first time in this project we identify UV sources as such stars by selecting suitable candidates in crowded fields as the bluest objects in colour-colour diagrams using observations from the Wise Observatory. These candidates are then studied using low-resolution spectroscopy, which allows the determination of spectral types to an accuracy of about one-half class, for 60 stars. Synthetic photometry of spectral data is performed in order to predict the expected UV emission, on the basis of the photometric information. These results are used along with the Hipparcos/Tycho (<I/239>) information, to search for subluminous stars. The comparison of the predicted emission with the FAUST measured magnitudes allows us to select 12 stars as highly probable evolved hot stars. High signal-to-noise spectra are obtained for nine of these stars, and Balmer line profiles are compared with the prediction of atmosphere models and with the spectrum of real stellar atmospheres. Among the nine candidates, six are classified as previously unrecognized sdB stars, and two as white dwarfs. Our result indicates that indeed more bright subluminous stars are still unrecognized in the existing samples.
1158. FCOS Ultra Compact Dwarf galaxies radial vel.
ID:
ivo://CDS.VizieR/J/A+A/418/445
Title:
FCOS Ultra Compact Dwarf galaxies radial vel.
Short Name:
J/A+A/418/445
Date:
21 Oct 2021
Publisher:
CDS
Description:
The relation between the Ultra Compact Dwarf galaxies (hereafter UCDs) recently discovered in the Fornax cluster (Drinkwater et al., 2003Natur.423..519D; Mieske et al., 2002, Cat. <J/A+A/383/823>) and the brightest globular clusters associated with the central galaxy NGC 1399 has been investigated in the spectroscopic Fornax Compact Object Survey FCOS. FCOS was carried out with the 2.5m du Pont telescope at Las Campanas, in the three nights of 2002/12/04 to 2002/12/06. Mieske et al. (2002, Cat. <J/A+A/383/823>) deals with the first part FCOS-1, this paper deals with the larger FCOS-2. The spectral resolution of FCOS was approx. 4{AA}. In the FCOS, 280 unresolved objects with 0<(V-I)<1.5mag in the magnitude space covering UCDs and bright globular clusters (18<V<21mag) were observed spectroscopically, among them 185 in FCOS-2. In the entire FCOS-sample there are five already known UCDs and 54 new Fornax members, 12 from FCOS-1 and 42 from FCOS-2.
1159. [Fe/H] and [{alpha}/Fe] in M31 dwarf galaxies
ID:
ivo://CDS.VizieR/J/ApJ/895/78
Title:
[Fe/H] and [{alpha}/Fe] in M31 dwarf galaxies
Short Name:
J/ApJ/895/78
Date:
15 Mar 2022 06:34:41
Publisher:
CDS
Description:
We present chemical abundances of red giant branch (RGB) stars in the dwarf spheroidal (dSph) satellite system of Andromeda (M31), using spectral synthesis of medium-resolution (R~6000) spectra obtained with the KeckII telescope and Deep Imaging Multi-Object Spectrometer spectrograph via the Spectroscopic and Photometric Landscape of Andromeda's Stellar Halo survey. We coadd stars according to their similarity in photometric metallicity or effective temperature to obtain a signal-to-noise ratio (S/N) high enough to measure average [Fe/H] and [{alpha}/Fe] abundances. We validate our method using high S/N spectra of RGB stars in Milky Way globular clusters, as well as deep observations for a subset of the M31 dSphs in our sample. For this set of validation coadds, we compare the weighted average abundance of the individual stars with the abundance determined from the coadd. We present individual and coadded measurements of [Fe/H] and [{alpha}/Fe] for stars in 10 M31 dSphs, including the first [{alpha}/Fe] measurements for And IX, XIV, XV, and XVIII. These fainter, less massive dSphs show declining [{alpha}/Fe] relative to [Fe/H], implying an extended star formation history (SFH). In addition, these dSphs also follow the same mass-metallicity relation found in other Local Group satellites. The conclusions we infer from coadded spectra agree with those from previous measurements in brighter M31 dSphs with individual abundance measurements, as well as conclusions from photometric studies. These abundances greatly increase the number of spectroscopic measurements of the chemical composition of M31's less massive dwarf satellites, which are crucial to understanding their SFH and interaction with the M31 system.
1160. FeII emission in SDSS type 1 AGNs
ID:
ivo://CDS.VizieR/J/ApJ/736/86
Title:
FeII emission in SDSS type 1 AGNs
Short Name:
J/ApJ/736/86
Date:
21 Oct 2021
Publisher:
CDS
Description:
We used a large, homogeneous sample of 4178 z<=0.8 Seyfert 1 galaxies and QSOs selected from the Sloan Digital Sky Survey to investigate the strength of FeII emission and its correlation with other emission lines and physical parameters of active galactic nuclei. We find that the strongest correlations of almost all the emission-line intensity ratios and equivalent widths (EWs) are with the Eddington ratio (L/L_Edd_), rather than with the continuum luminosity at 5100{AA} (L_5100_) or black hole mass (M_BH_); the only exception is the EW of ultraviolet FeII emission, which does not correlate at all with broad-line width, L_5100_, M_BH_, or L/L_Edd_. By contrast, the intensity ratios of both the ultraviolet and optical FeII emission to MgII{lambda}2800 correlate quite strongly with L/L_Edd_. Interestingly, among all the emission lines in the near-UV and optical studied in this paper (including MgII{lambda}2800, H{beta}, and [OIII]{lambda}5007), the EW of narrow optical FeII emission has the strongest correlation with L/L_Edd_. We hypothesize that the variation of the emission-line strength in active galaxies is regulated by L/L_Edd_ because it governs the global distribution of the hydrogen column density of the clouds gravitationally bound in the line-emitting region, as well as its overall gas supply. The systematic dependence on L/L_Edd_ must be corrected when using the FeII/MgII intensity ratio as a measure of the Fe/Mg abundance ratio to study the history of chemical evolution in QSO environments.