- ID:
- ivo://CDS.VizieR/J/MNRAS/450/397
- Title:
- Spectroscopic study of RGs in the Kepler field
- Short Name:
- J/MNRAS/450/397
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Thanks to the recent very high precision photometry of red giants from satellites such as Kepler, precise mass and radius values as well as accurate information of evolutionary stages are already established by asteroseismic approach for a large number of G-K giants. Based on the high-dispersion spectra of selected such 55 red giants in the Kepler field with precisely known seismic parameters (among which parallaxes are available for nine stars), we checked the accuracy of the determination method of stellar parameters previously applied to many red giants by Takeda et al. (2008PASJ...60..781T), since it may be possible to discriminate their complex evolutionary status by using the surface gravity versus mass diagram. We confirmed that our spectroscopic gravity and the seismic gravity satisfactorily agree with each other (to within ~0.1 dex) without any systematic difference. However, the mass values of He-burning red clump giants derived from stellar evolutionary tracks (~2-3 M_{sun}_) were found to be markedly larger by ~50 percent compared to the seismic values (~1-2 M_{sun}_) though such discrepancy is not seen for normal giants in the H-burning phase, which reflects the difficulty of mass determination from intricately overlapping tracks on the luminosity versus effective temperature diagram. This consequence implies that the mass results of many red giants in the clump region determined by Takeda et al. are likely to be significantly overestimated. We also compare our spectroscopically established parameters with recent literature values, and further discuss the prospect of distinguishing the evolutionary status of red giants based on the conventional (i.e. non-seismic) approach.
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Search Results
- ID:
- ivo://CDS.VizieR/J/A+A/391/641
- Title:
- Spectroscopic study of sigma Geminorum from IUE
- Short Name:
- J/A+A/391/641
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The IUE spectra of {sigma} Gem have been taken from the NASA IUE archive using IDL (Interactive Data Language). The spectra have been observed in 1979-1986 period. All the spectra analysed in the present study have NEWSIPS reductions and consist of 25 LWP, 8 LWR and 5 SWP images in high resolution, and 2 LWP and 14 SWP images in low dispersion. The emission lines, identified as activity indicators and originating in the chromosphere and transition region, are seen in the spectra. The emission line fluxes and equivalent widths are computed based on Gaussian profile fitting procedures to examine the existence of any line flux variation that depends on time or orbital phase. It was found that there is a flux variation with time and orbital phase that is in good agreement with the photometric light curve variation. By comparing the flux variation with simultaneous light curve variation, it can be shown that there is a relation between the ultraviolet flux variation and the spot activity of the system, as shown by Ayres et al. (1984ApJ...279..197A) and Engvold et al. (1988A&A...192..234E) based on their IUE (with IUESIPS reduction) spectral analysis. Moreover, it was inferred that there is no ultraviolet excess in {sigma} Gem by comparing the spectra of {beta} Gem taken as a comparison star. The Mg II h and k radial velocity curves of {sigma} Gem were in a good agreement with data obtained by Eker (1986MNRAS.221..947E) and Duemmler et al. (1997A&AS..123..209D).
- ID:
- ivo://CDS.VizieR/J/A+A/372/391
- Title:
- Spectroscopic Survey of Cl 0024+1654
- Short Name:
- J/A+A/372/391
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This wide-field spectroscopic survey of Cl 0024+1654 (ZwCl 0024.0+1652) is based on multi-object spectroscopy done with MOS on CFHT and LDSS_2 on WHT. Photometric measurements are based on CFHT/UH8k (I-band) and CFHT/CFH12k (V-band) images. The survey covers an area of 21x25arcmin^2^ around the centre of Cl 0024+1654. The catalogue includes the data from Dressler et al., 1999, Cat. <J/ApJS/122/51> with corrections made by us. Due to additional corrections provided by Alan Dressler since the paper was accepted, the present catalogue differs slightly from the description in the paper (see Historical note below).
- ID:
- ivo://CDS.VizieR/J/ApJ/834/176
- Title:
- Spectroscopic survey of M37 candidate members
- Short Name:
- J/ApJ/834/176
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results of a spectroscopic survey to characterize chromospheric activity, as measured by H{alpha} emission, in low-mass members of the 500Myr old open cluster M37. Combining our new measurements of H{alpha} luminosities (L_H{alpha}_) with previously cataloged stellar properties, we identify saturated and unsaturated regimes in the dependence of the L_H{alpha}_-to-bolometric luminosity ratio, L_H{alpha}_/L_bol_, on the Rossby number R_o_. All rotators with R_o_ smaller than 0.03+/-0.01 converge to an activity level of L_H{alpha}_/L_bol_=(1.27+/-0.02)x10^-4^. This saturation threshold (R_o,sat_=0.03+/-0.01) is statistically smaller than that found in most studies of the rotation-activity relation. In the unsaturated regime, slower rotators have lower levels of chromospheric activity, with L_H{alpha}_/L_bol_(R_o_) following a power-law of index {beta}=-0.51+/-0.02, slightly shallower than that found for a combined ~650Myr old sample of Hyades and Praesepe stars. By comparing this unsaturated behavior to that previously found for coronal activity in M37 (as measured via the X-ray luminosity, L_X_), we confirm that chromospheric activity decays at a much slower rate than coronal activity with increasing R_o_. While a comparison of L_H{alpha}_ and L_X_ for M37 members with measurements of both reveals a nearly 1:1 relation, removing the mass-dependencies by comparing instead L_H{alpha}_/L_bol_ and L_X_/L_bol_ does not provide clear evidence for such a relation. Finally, we find that R_o,sat_ is smaller for our chromospheric than for our coronal indicator of activity (R_o,sat_=0.03+/-0.01 versus 0.09+/-0.01). We interpret this as possible evidence for coronal stripping.
- ID:
- ivo://CDS.VizieR/J/AJ/130/1871
- Title:
- Spectroscopic survey of M dwarfs
- Short Name:
- J/AJ/130/1871
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have constructed a sample of M dwarfs out to a distance of ~100pc. This sample of 605 stars (574 M dwarfs and 31 K dwarfs) have been spectroscopically observed, yielding spectral types, radial velocities, H{alpha} equivalent widths, and molecular band indices. Photometric observations have been compiled, with photographic plates providing RI magnitudes and JHKs magnitudes from Two Micron All Sky Survey (Cat. <II/246>) observations. Proper motions were determined by a match to USNO-B (Cat. <I/284>), and distances were computed employing a spectroscopic parallax, allowing the computation of UVW space motions.
- ID:
- ivo://CDS.VizieR/J/ApJS/190/233
- Title:
- Spectroscopy and abundances of SINGS galaxies
- Short Name:
- J/ApJS/190/233
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present intermediate-resolution optical spectrophotometry of 65 galaxies obtained in support of the Spitzer Infrared Nearby Galaxies Survey (SINGS). For each galaxy we obtain a nuclear, circumnuclear, and semi-integrated optical spectrum designed to coincide spatially with mid- and far-infrared spectroscopy from the Spitzer Space Telescope. We make the reduced, spectrophotometrically calibrated one-dimensional spectra, as well as measurements of the fluxes and equivalent widths of the strong nebular emission lines, publically available. We use optical emission-line ratios measured on all three spatial scales to classify the sample into star-forming, active galactic nuclei (AGNs), and galaxies with a mixture of star formation and nuclear activity. We find that the relative fraction of the sample classified as star forming versus AGN is a strong function of the integrated light enclosed by the spectroscopic aperture. We supplement our observations with a large database of nebular emission-line measurements of individual HII regions in the SINGS galaxies culled from the literature. We use these ancillary data to conduct a detailed analysis of the radial abundance gradients and average HII-region abundances of a large fraction of the sample. We combine these results with our new integrated spectra to estimate the central and characteristic (globally averaged) gas-phase oxygen abundances of all 75 SINGS galaxies. We conclude with an in-depth discussion of the absolute uncertainty in the nebular oxygen abundance scale.
- ID:
- ivo://CDS.VizieR/J/A+A/500/947
- Title:
- Spectroscopy and photometry in A2744 and A2537
- Short Name:
- J/A+A/500/947
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The current paradigm of cosmic formation and evolution of galaxy clusters foresees growth mostly through merging. Galaxies in the infall region or in the core of a cluster undergo transformations owing to different environmental stresses. For two X-ray luminous clusters at redshift z~0.3 with opposite X-ray morphologies (i.e., dynamical states), RXCJ0014.3-3022 and RXCJ2308.3-0211, we assess differences in galaxy populations as a function of cluster topography. This is a pilot study for the joint X-ray and optical analysis of the REFLEX-DXL cluster sample.
- ID:
- ivo://CDS.VizieR/J/AJ/144/81
- Title:
- Spectroscopy and photometry of CV candidates
- Short Name:
- J/AJ/144/81
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Catalina Real Time Survey (CRTS) has found over 500 cataclysmic variable (CV) candidates, most of which were previously unknown. We report here on follow-up spectroscopy of 36 of the brighter objects. Nearly all of the spectra are typical of CVs at minimum light. One object appears to be a flare star, while another has a spectrum consistent with a CV but lies, intriguingly, at the center of a small nebulosity. We measured orbital periods for eight of the CVs, and estimated distances for two based on the spectra of their secondary stars. In addition to the spectra, we obtained direct imaging for an overlapping sample of 37 objects, for which we give magnitudes and colors. Most of our new orbital periods are shortward of the so-called period gap from roughly 2 to 3hr. By considering the cross-identifications between the Catalina objects and other catalogs such as the Sloan Digital Sky Survey, we argue that a large number of CVs remain uncataloged. By comparing the CRTS sample to lists of previously known CVs that CRTS does not recover, we find that the CRTS is biased toward large outburst amplitudes (and hence shorter orbital periods). We speculate that this is a consequence of the survey cadence.
- ID:
- ivo://CDS.VizieR/J/AJ/150/190
- Title:
- Spectroscopy and Stromgren photometry of HR 1040
- Short Name:
- J/AJ/150/190
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A time-series analysis of spectroscopic and photometric observables of the A0 Ia supergiant HR 1040 has been performed, including equivalent widths, radial velocities, and Stromgren photometric indices. The data, obtained from 1993 through 2007, include 152 spectroscopic observations from the Ritter Observatory 1m telescope and 269 Stromgren photometric observations from the Four College Automated Photoelectric Telescope. Typical of late B- and early A-type supergiants, HR 1040 has a highly variable H{alpha} profile. The star was found to have an intermittent active phase marked by correlation between the H{alpha} absorption equivalent width and blue-edge radial velocity and by photospheric connections observed in correlations to equivalent width, second moment and radial velocity in SiII{lambda}{lambda}6347,6371. High-velocity absorption (HVA) events were observed only during this active phase. HVA events in the wind were preceded by photospheric activity, including SiII radial velocity oscillations 19-42 days prior to onset of an HVA event and correlated increases in SiII W_{lambda}_ and second moment from 13 to 23 days before the start of the HVA event. While increases in various line equivalent widths in the wind prior to HVA events have been reported in the past in other stars, our finding of precursors in enhanced radial velocity variations in the wind and at the photosphere is a new result.
- ID:
- ivo://CDS.VizieR/J/A+A/540/A27
- Title:
- Spectroscopy in Galactic globular clusters
- Short Name:
- J/A+A/540/A27
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Well determined radial velocities and abundances are essential for analyzing the properties of the Globular Cluster system of the Milky Way. However more than 50% of these clusters have no spectroscopic measure of their metallicity. In this context, this work provides new radial velocities and abundances for twenty Milky Way globular clusters which lack or have poorly known values for these quantities. The radial velocities and abundances are derived from spectra obtained at the CaII triplet using the FORS2 imager and spectrograph at the VLT, calibrated with spectra of red giants in a number of clusters with well determined abundances. For about half of the clusters in our sample we present signifiant revisions of the existing velocities or abundances, or both.
