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1901. Optical spectral variability of IRAS 20508+2011
ID:
ivo://CDS.VizieR/J/AZh/83/265
Title:
Optical spectral variability of IRAS 20508+2011
Short Name:
J/AZh/83/265
Date:
21 Oct 2021
Publisher:
CDS
Description:
Based on high-resolution spectra we revealed variability of the optical spectrum of the cool star identified with the IR source IRAS 20508+2011. Over the five years of our observations, the radial velocity derived from photospheric absorption lines varied in the interval V_r_=15-30km/s. In the same time, the H(alpha) profile varied from an intense bell-shaped emission line with a small absorption to 2-peaked emission with a central absorption feature below the continuum level. At all but one epoch, the positions of the metallic photospheric lines were systematically shifted relative to the H(alpha) emission: Delta V_r_=V_r_(met)-V_r_(Halpha,emis)~-23km/s. The NaD doublet lines shown a complex profile with broad (half-width about 120km/s) emission and photospheric absorption, as well as an interstellar component. We used model atmospheres to determine the physical parameters and chemical composition of the star's atmosphere: Teff=4800K, logg=1.5, Vt=4.0km/s and metallicity [Fe/H]=-0.36. We detected overabundances of oxygen [O/Fe]=+1.79 (with the ratio [C/O]~-0.9), and alpha-process elements, as well as a deficit of heavy metals. The totality of the parameters suggests that the optical component of IRAS 20508+2011 is an "O-rich" AGB star with luminosity M_v_~-3mag that is close to its evolution transition to the post-AGB stage.
1902. 1995-2000 optical spectra of CH Cyg
ID:
ivo://CDS.VizieR/J/A+A/622/A45
Title:
1995-2000 optical spectra of CH Cyg
Short Name:
J/A+A/622/A45
Date:
21 Oct 2021
Publisher:
CDS
Description:
CH Cyg is one of the most studied symbiotic stars. Its properties, however, are still not well known. Two main periods, about 15 years and 750-days, are known in the photometric and spectroscopic variations, and two models are proposed for these origins. One is a binary system with an orbital period of 15 years consisting of a hot component and pulsating red giant with a 750-day period. The other is a triple system consisting of an inner symbiotic binary with an orbital period of about 750-days and third component with an orbital period of 15 years. Several active stages have been observed since the 1970s during which the object brightened up by {Delta}U=3-5mag and prominent emission lines appeared. Large mass outflows were observed at some active stages. The spectral variation of CH Cyg has been monitored at Asiago Observatories to understand the problems mentioned above. We have analysed spectra obtained in the time period from 1995 to 2004 which covers an active stage during the years 1998-2000. High- and low-resolution optical spectra obtained at the Asiago Observatories are used. Narrow absorption lines of FeI, CrI, TiI, and so on appeared in 1998 at an early phase of the active stage. These lines are clearly distinguished from those of the M-type giant and are typically found on the spectrum of early A-type dwarfs. They were redshifted by about 30km/s, with respect to the absorption lines of the M-type giant. Assuming that their radial velocities represent the orbital motion of the hot component, its semi-amplitude is estimated to be 37.0+/60.5km/s.
1903. Optical Spectra of DENIS Brown Dwarf Candidate
ID:
ivo://CDS.VizieR/J/A+A/338/1066
Title:
Optical Spectra of DENIS Brown Dwarf Candidate
Short Name:
J/A+A/338/1066
Date:
21 Oct 2021
Publisher:
CDS
Description:
Optical spectra for candidate brown dwarfs from the DENIS Mini-survey are provided. These are the spectra used to in Figure 1 of the paper.
1904. Optical spectra of 7 hot UV bright stars in GC
ID:
ivo://CDS.VizieR/J/A+A/335/510
Title:
Optical spectra of 7 hot UV bright stars in GC
Short Name:
J/A+A/335/510
Date:
21 Oct 2021
Publisher:
CDS
Description:
We have obtained medium-resolution spectra of seven UV-bright stars discovered on images of four southern globular clusters obtained with the Ultraviolet Imaging Telescope (UIT). Effective temperatures, surface gravities and helium abundances are derived from LTE and non-LTE model atmosphere fits. Three of the stars have sdO spectra, including M4-Y453 (T_eff_=58800K, logg=5.15), NGC 6723-III60 (T_eff_=40600K, logg=4.46) and NGC 6752-B2004 (T_eff_=37000K, logg=5.25). All seven stars lie along either post-extended horizontal branch (EHB) or post-early AGB evolutionary tracks. The post-early AGB stars show solar helium abundances, while the post-EHB stars are helium deficient, similar to their EHB progenitors. Based on observations collected at the European Southern Observatory (ESO No 57.E-0101)
1905. Optical spectra of IGR J21343+4738
ID:
ivo://CDS.VizieR/J/A+A/561/A137
Title:
Optical spectra of IGR J21343+4738
Short Name:
J/A+A/561/A137
Date:
21 Oct 2021
Publisher:
CDS
Description:
Present X-ray missions are regularly discovering new X-ray and gamma-ray sources. The identification of their counterparts at other wavelengths allows us to determine their nature. The main goal of this work is to determine the properties of the optical counterpart to the INTEGRAL source IGR J21343+4738, and to study its long-term optical variability. Although its nature as a Be/X-ray binary has been suggested, little is known about its physical parameters. We have been monitoring IGR J21343+4738 since 2009 in the optical band. We present BVRI optical photometric and spectroscopic observations covering the wavelength band 4000-7500{AA}. The photometric data allowed us to derive the colour excess E(B-V) and estimate the distance. The blue-end spectra were used to determine the spectral type of the optical companion, while the spectra around the Halpha line allowed us to study the long-term structural changes in the circumstellar disc.
1906. Optical spectra of 12 Miras
ID:
ivo://CDS.VizieR/J/A+A/531/A88
Title:
Optical spectra of 12 Miras
Short Name:
J/A+A/531/A88
Date:
21 Oct 2021
Publisher:
CDS
Description:
Miras are long-period variables thought to be in the asymptotic giant branch (AGB) phase of evolution. In about one percent of known Miras, the pulsation period is changing. It has been speculated that this changing period is the consequence of a recent thermal pulse in these stars. We aim to clarify the evolutionary state of these stars, and to determine in particular whether or not they are in the thermally-pulsing (TP-)AGB phase. One important piece of information that has been neglected so far when determining the evolutionary state is the presence of the radio-active s-process element technetium (Tc). We obtained high-resolution, high signal-to-noise-ratio optical spectra of a dozen prominent Mira variables with changing pulsation period to search for this indicator of TPs and dredge-up. We also use the spectra to measure lithium (Li) abundances. Furthermore, we establish the evolutionary states of our sample stars by means of their present-day periods and luminosities. Among the twelve sample stars observed in this programme, five were found to show absorption lines of Tc. BH Cru is found to be a carbon-star, its period increase in the past decades possibly having stopped by now. We report a possible switch in the pulsation mode of T UMi from Mira-like to semi-regular variability in the past two years. R Nor, on the other hand, is probably a fairly massive AGB star, which could be true for all meandering Miras. Finally, we assign RU Vul to the metal-poor thick disk with properties very similar to the short-period, metal-poor Miras. We conclude that there is no clear correlation between period change type and Tc presence. The stars that are most likely to have experienced a recent TP are BH Cru and R Hya, although their rates of period change are quite different.
1907. Optical spectra of new low-excitation PNs
ID:
ivo://CDS.VizieR/J/A+A/563/A63
Title:
Optical spectra of new low-excitation PNs
Short Name:
J/A+A/563/A63
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present mid-resolution spectroscopic observations of four new planetary nebula (PN) candidates selected from the INT/WFC Photometric H-alpha Survey of the Northern Galactic Plane (IPHAS) and Deep Sky Hunter (DSH) catalogues. The PN status of these objects was confirmed by mid-resolution spectra. Based on the locations of these objects in the log(H-alpha/[NII]) versus log (H-alpha/[SII]) diagnostic diagram, these sources are evolved low- excitation PNs.
1908. Optical spectra of 24um galaxies in COSMOS. I.
ID:
ivo://CDS.VizieR/J/ApJ/680/939
Title:
Optical spectra of 24um galaxies in COSMOS. I.
Short Name:
J/ApJ/680/939
Date:
21 Oct 2021
Publisher:
CDS
Description:
We study zCOSMOS-bright optical spectra for 609 Spitzer MIPS 24um-selected galaxies with S_24um_>0.30mJy and I<22.5 (AB mag) over 1.5deg^2^ of the COSMOS field.
1909. Optical spectroscopic atlas of low-redshift AGN
ID:
ivo://CDS.VizieR/J/ApJS/145/199
Title:
Optical spectroscopic atlas of low-redshift AGN
Short Name:
J/ApJS/145/199
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present a spectral atlas of the H{beta} region for 215 type 1 AGNs (luminous Seyfert 1/radio galaxy nuclei and low-z quasars) up to z~0.8. Line profiles and measures were derived from the database of intermediate resolution spectra (R>~1000) with average continuum level S/N ratio ~30. Parameters including rest frame equivalent width and FWHM are provided for the FeII_opt_ blend at {lambda}4570, H{beta}, HeII {lambda}4686, and the [OIII] {lambda}{lambda}4959, 5007 emission lines. We extract clean broad component H{beta} profiles and provide wavelength measurements at 0, 1/4, 1/2, 3/4, and 0.9 peak intensity levels in order to permit a quantitative definition of the H{beta} broad component for statistical studies. We also discuss sources of uncertainty, selection effects, and biases in our sample. The data are especially important for tests of the eigenvector 1 parameter space occupation and correlation. We show that the I Zw 1 template FeII_opt_ spectrum reproduces well the observed FeII_opt_ emission for a wide range of line width and strength. A detailed analysis of the data within the eigenvector 1 context is deferred to a companion paper.
1910. Optical spectroscopic atlas of MOJAVE AGNs
ID:
ivo://CDS.VizieR/J/other/RMxAA/48.9
Title:
Optical spectroscopic atlas of MOJAVE AGNs
Short Name:
J/other/RMxAA/48
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present an optical spectroscopic atlas for 123 core-dominated radio-loud active galactic nuclei with relativistic jets, drawn from the MOJAVE/2cm (Monitoring of Jets in AGN with VLBA Experiments) sample at 15GHz. It is the first time that spectroscopic and photometric parameters for a large sample of such type of AGN are presented.

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