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391. Chemical composition of V2314 Oph
ID:
ivo://CDS.VizieR/J/AJ/134/926
Title:
Chemical composition of V2314 Oph
Short Name:
J/AJ/134/926
Date:
21 Oct 2021
Publisher:
CDS
Description:
We investigated V2314 Oph using high-resolution (R=45000) spectral observations. The atmospheric parameters were determined using iron-line abundance analysis. We derived a mean effective temperature of Teff=7510K, mean surface gravity of logg=3.30, metallicity of [Fe/H]=-0.59, and rotation velocity of vsini=38km/s. The abundances of 19 chemical elements were determined.
392. Chemical compositions of 26 outer halo stars
ID:
ivo://CDS.VizieR/J/ApJ/706/1095
Title:
Chemical compositions of 26 outer halo stars
Short Name:
J/ApJ/706/1095
Date:
21 Oct 2021
Publisher:
CDS
Description:
Chemical abundances of 26 metal-poor dwarfs and giants are determined from high-resolution and high signal-to-noise ratio spectra obtained with the Subaru/High Dispersion Spectrograph. The sample is selected so that most of the objects have outer-halo kinematics. Self-consistent atmospheric parameters were determined by an iterative procedure based on spectroscopic analysis. Abundances of 13 elements, including {alpha}-elements (Mg, Si, Ca, Ti), odd-Z light elements (Na, Sc), iron-peak elements (Cr, Mn, Fe, Ni, Zn), and neutron-capture elements (Y, Ba), are determined by two independent data reduction and local thermodynamic equillibrium analysis procedures, confirming the consistency of the stellar parameters and abundances results.
393. Chemical compositions of 11 RR Lyrae
ID:
ivo://CDS.VizieR/J/ApJS/197/29
Title:
Chemical compositions of 11 RR Lyrae
Short Name:
J/ApJS/197/29
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present a detailed abundance study of 11 RR Lyrae ab-type variables: AS Vir, BS Aps, CD Vel, DT Hya, RV Oct, TY Gru, UV Oct, V1645 Sgr, WY Ant, XZ Aps, and Z Mic. High-resolution and high signal-to-noise ratio echelle spectra of these variables were obtained with the 2.5m du Pont telescope at the Las Campanas Observatory. We obtained more than 2300 spectra, roughly 200 spectra per star, distributed more or less uniformly throughout the pulsational cycles. A new method has been developed to obtain the initial effective temperatures of our sample stars at a specific pulsational phase. We find that the abundance ratios are generally consistent with those of similar metallicity field stars in different evolutionary states and throughout the pulsational cycles for RR Lyrae stars. TY Gru remains the only n-capture enriched star among the RRab in our sample.
394. Chemical evolution of SMC planetary nebulae
ID:
ivo://CDS.VizieR/J/A+A/472/101
Title:
Chemical evolution of SMC planetary nebulae
Short Name:
J/A+A/472/101
Date:
21 Oct 2021
Publisher:
CDS
Description:
We investigate the chemical evolution of the Small Magellanic Cloud (SMC) based on abundance data of planetary nebulae (PNe). The main goal is to investigate the time evolution of the oxygen abundance in this galaxy by deriving an age-metallicity relation. Such a relation is of fundamental importance as an observational constraint for chemical evolution models of the SMC. We have used high quality PNe data to derive the properties of the progenitor stars, so that the stellar ages could be estimated. We collected a large number of measured spectral fluxes for each nebula and derived accurate physical parameters and nebular abundances. New spectral data for a sample of SMC PNe obtained between 1999 and 2002 are also presented. These data are used with data available in the literature to improve the accuracy of the fluxes for each spectral line.
395. Chemistry in infrared dark clouds
ID:
ivo://CDS.VizieR/J/A+A/527/A88
Title:
Chemistry in infrared dark clouds
Short Name:
J/A+A/527/A88
Date:
21 Oct 2021
Publisher:
CDS
Description:
Massive stars play an important role in shaping the structure of galaxies. Infrared dark clouds (IRDCs), with their low temperatures and high densities, have been identified as the potential birthplaces of massive stars. In order to understand the formation processes of massive stars, the physical and chemical conditions in infrared dark clouds have to be characterized. The goal of this paper is to investigate the chemical composition of a sample of southern infrared dark clouds. One important aspect of the observations is to check, whether the molecular abundances in IRDCs are similar to the low-mass pre-stellar cores, or if they show signatures of more evolved evolutionary stages. We performed observations toward 15 IRDCs in the frequency range between 86 and 93GHz using the 22-m Mopra radio telescope. In total, 13 molecular species comprising N_2_H^+^, ^13^CS, CH_3_CN, HC_3_N, HNC, HCO^+^, HCN, HNCO, C_2_H, SiO, H^13^CO^+^, H^13^CN, and CH_3_C_2_H were observed for all targets. Hence, we included in general species appropriate for elevated densities, where some of them trace the more quiescent gas, while others are sensitive to more dynamical processes.
396. Chemo-kinematic properties of Aquarius
ID:
ivo://CDS.VizieR/J/A+A/634/A10
Title:
Chemo-kinematic properties of Aquarius
Short Name:
J/A+A/634/A10
Date:
21 Oct 2021
Publisher:
CDS
Description:
Dwarf galaxies found in isolation in the Local Group (LG) are unlikely to have interacted with the large LG spirals, and therefore environmental effects such as tidal and ram-pressure stripping should not be the main drivers of their evolution. We aim to provide insight into the internal mechanisms shaping LG dwarf galaxies by increasing our knowledge of the internal properties of isolated systems. Here we focus on the evolved stellar component of the Aquarius dwarf galaxy, whose kinematic and metallicity properties have only recently started to be explored. Spectroscopic data in the region of the near-infrared Ca~II triplet lines has been obtained with FORS2 at the Very Large Telescope for 53 red giant branch (RGB) stars. These data are used to derive line-of-sight velocities and [Fe/H] of the individual RGB stars. We have derived a systemic velocity of -142.2^+1.8^_-1.8_km/s, in agreement with previous determinations from both the HI gas and stars. The internal kinematics of Aquarius appears to be best modelled by a combination of random motions (l.o.s. velocity dispersion of 10.3^+1.6^_-1.3_km/s) and linear rotation (with a gradient -5.0^+1.6^_-1.9_km/s/arcmin) along a P.A.=139_-27_^+17^deg, broadly consistent with the optical projected major axis. This rotation signal is significantly misaligned or even counter-rotating to that derived from the HI gas. We also find the tentative presence of a mild negative metallicity gradient and indications that the metal-rich stars have a colder velocity dispersion than the metal-poor ones. This work represents a significant improvement with respect to previous measurements of the RGB stars of Aquarius, as it doubles the number of member stars already studied in the literature. We speculate that the misaligned rotation between the HI gas and evolved stellar component might have been the result of recent accretion of HI gas, or re-accretion after gas-loss due to internal stellar feedback.
397. 3C 273 high energy spectrum
ID:
ivo://CDS.VizieR/J/A+A/576/A122
Title:
3C 273 high energy spectrum
Short Name:
J/A+A/576/A122
Date:
21 Oct 2021
Publisher:
CDS
Description:
The high energy spectrum of 3C 273 is usually understood in terms of inverse-Compton emission in a relativistic leptonic jet. This model predicts variability patterns and delays that could be tested with simultaneous observations from the radio to the GeV range. The instruments IBIS, SPI, JEM-X on board INTEGRAL, PCA on board RXTE, and LAT on board Fermi have enough sensitivity to follow the spectral variability of 3C 273 from the keV to the GeV. We looked for correlations between the different energy bands, including radio data at 37GHz collected at the Metsahovi Radio Observatory and built quasi-simultaneous multiwavelength spectra in the high energy domain when the source is flaring either in the X-rays or in the {gamma} rays.
398. CH_2_NH accurate rotational rest frequencies
ID:
ivo://CDS.VizieR/J/A+A/544/A19
Title:
CH_2_NH accurate rotational rest frequencies
Short Name:
J/A+A/544/A19
Date:
21 Oct 2021
Publisher:
CDS
Description:
Methanimine (CH_2_NH) has been detected in different astronomical sources, both galactic (as in several "hot cores", the circumstellar enevolope IRC+10216, and the L183 pre-stellar core) and extragalactic, and is considered a pre-biotic interstellar molecule. Its ground-state rotational spectrum has been studied in the laboratory up to 172GHz, well below the spectral ranges covered by Herschel/HIFI and the ALMA bands 9 and 10. In this laboratory study, we extend into the submillimetre-wave region the detection of the rotational spectrum of CH_2_NH in its vibrational ground state.
399. Chromospheric activity for CPS stars
ID:
ivo://CDS.VizieR/J/ApJ/725/875
Title:
Chromospheric activity for CPS stars
Short Name:
J/ApJ/725/875
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present time series measurements of chromospheric activity for more than 2600 main-sequence and subgiant stars on the California Planet Search (CPS) program with spectral types ranging from about F5V to M4V for main-sequence stars and from G0IV to about K5IV for subgiants. The large data set of more than 44000 spectra allows us to identify an empirical baseline floor for chromospheric activity as a function of color and height above the main sequence. We define {Delta}S as an excess in emission in the CaII H and K lines above the baseline activity floor and define radial velocity jitter as a function of {Delta}S and B-V for main-sequence and subgiant stars. Although the jitter for any individual star can always exceed the baseline level, we find that K dwarfs have the lowest level of jitter. The lack of correlation between observed jitter and chromospheric activity in K dwarfs suggests that the observed jitter is dominated by instrumental or analysis errors and not astrophysical noise sources. Thus, given the long-term precision for the CPS program, radial velocities are not correlated with astrophysical noise for chromospherically quiet K dwarf stars, making these stars particularly well suited for the highest precision Doppler surveys. Chromospherically quiet F and G dwarfs and subgiants exhibit higher baseline levels of astrophysical jitter than K dwarfs. Despite the fact that the rms in Doppler velocities is correlated with the mean chromospheric activity, it is rare to see one-to-one correlations between the individual time series activity and Doppler measurements, diminishing the prospects for correcting activity-induced velocity variations in F and G dwarfs.
400. Chromospheric activity in late-type stars
ID:
ivo://CDS.VizieR/J/A+A/469/309
Title:
Chromospheric activity in late-type stars
Short Name:
J/A+A/469/309
Date:
21 Oct 2021
Publisher:
CDS
Description:
The main chromospheric activity indicator is the S index, which is the ratio of the flux in the core of the CaII H and K lines to the continuum nearby, and is well studied for stars from F to K. Another chromospheric proxy is the Halpha line, which is believed to be tightly correlated with the CaII index. In this work we characterize both chromospheric activity indicators, the one associated with the H and K CaII lines and the other with Halpha, for the whole range of late type stars, from F to M.

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