- ID:
- ivo://CDS.VizieR/J/AZh/74/42
- Title:
- RATAN-600 radio sources spectra
- Short Name:
- J/AZh/74/42
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A multifrequency deep survey of a band of sky with the declination of the source SS 433 ({delta}~5{deg}+/-20') was performed as part of the "Kholod" program on the RATAN-600 in 1987-1988. The right ascension intervals covered by the survey are 0h<{alpha}<14h and 18h<{alpha}<24h. The spectral properties of 400 sources from the RC catalog were determined for the first time by using only RATAN-600 data. The maximum in the flux density distribution for these sources at the central wavelength, {lambda}7.6cm, occurs at ~30mJy. The lower flux limits for the sample at wavelengths of 3.9, 7.6, 13.0, and 31.0cm are 16, 9, 37, and 61mJy, respectively. These observations provide the first flux estimates at 13.0 and 31.0cm for 90% of the sources. Spectra were measured for the first time for 112 sources (28%) and were revised for 90 sources (23%). The maximum in the spectral index distribution for the entire sample in the interval from {lambda}{lambda}7.6-31.0cm occurs at {alpha}=-0.86+/-0.04 (S_v_~{nu}^{alpha}^). The spectra of some 20 of the sample sources (5%) are peaked at roughly 1GHz, and about 40 spectra (10%) have low-frequency breaks. Roughly 70 sources (19%) have flat spectra ({alpha}>-0.5), and 64 (18%) have very steep spectra ({alpha}<-1.1).
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Search Results
- ID:
- ivo://CDS.VizieR/J/other/BSAO/40.128
- Title:
- RATAN-600 radio sources spectra
- Short Name:
- J/other/BSAO/40.
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In accordance with the program "Cold" in 1987-1988 and in 1996 deep surveys of the sky strip at the declination of the source SS 433 ({delta}~5{deg}+/-20') were made at the radio telescope RATAN-600. For the first time spectral characteristics of 400 sources from the RC catalog have been determined using only the data obtained with the RATAN-600. The maximum of the flux density distributions at the central wavelength {lambda}7.6cm is ~30mJy. The lower flux limit in the sample of the sources at the wavelengths 3.9, 7.6, 13.0, 31.0cm is 16, 9, 37, 61mJy, respectively. Spectra of 112 sources (28%) have been obtained for the first time, spectra of 90 (23%) sources have been made more accurate. For the first time the fluxes at the wavelengths 2.7, 3.9, 13.0 and 31.0cm (90% of data) have been measured. The maximum of the distribution of spectral indices for the entire sample of sources in the interval {lambda}{lambda}7.6-31.0cm falls at {alpha}=-0.86+/-0.04 (S_{nu}_{prop.to}{nu}^alpha^). About 20 (5%) sources of the sample have a maximum of radiation at a frequency of about 1GHz (GHz-Peaked-Spectrum radio sources), about 40 (10%) have a low-frequency cut off of the spectrum. About 70 (19%) sources have flat spectra ({alpha}>-0.5), 64 (18%) very steep ({alpha}<-1.1) spectra.
- ID:
- ivo://CDS.VizieR/J/ApJ/897/78
- Title:
- RAVE J183013.5-455510 equivalent-width measurements
- Short Name:
- J/ApJ/897/78
- Date:
- 15 Mar 2022 04:12:46
- Publisher:
- CDS
- Description:
- We report on the spectroscopic analysis of RAVE-J183013.5-455510, an extremely metal-poor star, highly enhanced in CNO, and with discernible contributions from the rapid neutron-capture process. There is no evidence of binarity for this object. At [Fe/H]=-3.57, this star has one of the lowest metallicities currently observed, with 18 measured abundances of neutron-capture elements. The presence of Ba, La, and Ce abundances above the solar system r-process predictions suggests that there must have been a non-standard source of r-process elements operating at such low metallicities. One plausible explanation is that this enhancement originates from material ejected at unusually high velocities in a neutron star merger event. We also explore the possibility that the neutron-capture elements were produced during the evolution and explosion of a rotating massive star. In addition, based on comparisons with yields from zero-metallicity faint supernova, we speculate that RAVE-J1830-4555 was formed from a gas cloud pre-enriched by both progenitor types. From analysis based on Gaia DR2 measurements, we show that this star has orbital properties similar to the Galactic metal-weak thick-disk stellar population.
- ID:
- ivo://CDS.VizieR/J/AJ/142/193
- Title:
- RAVE stellar elemental abundances (DR1)
- Short Name:
- J/AJ/142/193
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present chemical elemental abundances for 36561 stars observed by the RAdial Velocity Experiment (RAVE), an ambitious spectroscopic survey of our Galaxy at Galactic latitudes |b|>25{deg} and with magnitudes in the range 9<I_DENIS_<13. RAVE spectra cover the Ca-triplet region at 8410-8795{AA} with resolving power R~7500. This first data release of the RAVE chemical catalog is complementary to the third RAVE data release of radial velocities and stellar parameters, and it contains chemical abundances for the elements Mg, Al, Si, Ca, Ti, Fe, and Ni, with a mean error of ~0.2dex, as judged from accuracy tests performed on synthetic and real spectra. Abundances are estimated through a dedicated processing pipeline in which the curve of growth of individual lines is obtained from a library of absorption line equivalent widths to construct a model spectrum that is then matched to the observed spectrum via a {chi}^2^ minimization technique. We plan to extend this pipeline to include estimates for other elements, such as oxygen and sulfur, in future data releases.
- ID:
- ivo://CDS.VizieR/J/A+A/439/1107
- Title:
- R-band spectra for 13 early-type supergiants
- Short Name:
- J/A+A/439/1107
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This catalogue contains R-band spectra for 13 early-type supergiants. Spectral types range from B0 to A6, all with luminosity classes Ia or Iab. Eight of the stars are classified as having emission. The wavelength range is 5846 to 7030{AA} at a spectral resolution of 1.2{AA}, and a signal-to-noise ratio of 400 or above. Identification of spectral lines in supergiant spectra can be found in Chentsov et al. (2003A&A...397.1035C). The reader should be aware of the blends of atmospheric telluric lines that contaminate the spectra in the ranges 5870-5995{AA}, 6270-6315{AA}, 6470-6500{AA}, and 6850{AA} onwards.
- ID:
- ivo://CDS.VizieR/J/ApJ/858/L7
- Title:
- Red clump stars selected from LAMOST and APOGEE
- Short Name:
- J/ApJ/858/L7
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Core helium-burning red clump (RC) stars are excellent standard candles in the Milky Way. These stars may have more precise distance estimates from spectrophotometry than from Gaia parallaxes beyond 3kpc. However, RC stars have values of Teff and logg that are very similar to some red giant branch (RGB) stars. Especially for low-resolution spectroscopic studies where Teff, logg, and [Fe/H] can only be estimated with limited precision, separating RC stars from RGB through established methods can incur ~20% contamination. Recently, Hawkins+ (2018ApJ...853...20H) demonstrated that the additional information in single-epoch spectra, such as the C/N ratio, can be exploited to cleanly differentiate RC and RGB stars. In this second paper of the series, we establish a data-driven mapping from spectral flux space to independently determined asteroseismic parameters, the frequency and the period spacing. From this, we identify 210371 RC stars from the publicly available LAMOST DR3 and APOGEE DR14 data, with ~9% of contamination. We provide an RC sample of 92249 stars with a contamination of only ~3%, by restricting the combined analysis to LAMOST stars with S/N_pix_>=75. This demonstrates that high-signal-to-noise ratio (S/N), low-resolution spectra covering a broad wavelength range can identify RC samples at least as pristine as their high- resolution counterparts. As coming and ongoing surveys such as TESS, DESI, and LAMOST will continue to improve the overlapping training spectroscopic-asteroseismic sample, the method presented in this study provides an efficient and straightforward way to derive a vast yet pristine sample of RC stars to reveal the three-dimensional (3D) structure of the Milky Way.
- ID:
- ivo://CDS.VizieR/J/A+A/615/A17
- Title:
- Red giant Aluminium abundances in NGC 2808
- Short Name:
- J/A+A/615/A17
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We observed a sample of 90 red giant branch (RGB) stars in NGC 2808 using FLAMES/GIRAFFE and the high resolution grating with the set up HR21. These stars have previous accurate atmospheric parameters and abundances of light elements. We derived aluminium abundances for them from the strong doublet AlI 8772-8773 Angstrom as in previous works of our group. In addition, we were able to estimate the relative CN abundances for 89 of the stars from the strength of a large number of CN features. When adding self consistent abundances from previous UVES spectra analysed by our team, we gathered [Al/Fe] ratios for a total of 108 RGB stars in NGC 2808. The full dataset of proton-capture elements is used to explore in details the five spectroscopically detected discrete components in this globular cluster. We found that different classes of polluters are required to reproduce the (anti)-correlations among all proton-capture elements in the populations P2, I1, and I2 with intermediate composition. This is in agreement with the detection of lithium in lower RGB second generation stars, requiring at least two kind of polluters. To have chemically homogeneous populations the best subdivision of our sample is into six components, as derived from statistical cluster analysis. By comparing different diagrams [element/Fe] vs [element/Fe] we show for the first time that a simple dilution model is not able to reproduce all the sub-populations in this cluster. Polluters of different masses are required. NGC 2808 is confirmed to be a tough challenge to any scenario for globular cluster formation.
2118. Red giants of NGC 1851
- ID:
- ivo://CDS.VizieR/J/A+A/658/A80
- Title:
- Red giants of NGC 1851
- Short Name:
- J/A+A/658/A80
- Date:
- 22 Feb 2022
- Publisher:
- CDS
- Description:
- NGC 1851 is one of several globular clusters for which multiple stellar populations of the subgiant branch have been clearly identified and a difference in metallicity detected. A crucial piece of information on the formation history of this cluster can be provided by the sum of A(C+N+O) abundances. However, these values have lacked a general consensus thus far. The separation of the subgiant branch can be based on age and/or A(C+N+O) abundance differences. Our main aim was to determine carbon, nitrogen, and oxygen abundances for evolved giants in the globular cluster NGC 1851 in order to check whether or not the double populations of stars are coeval. High-resolution spectra, observed with the FLAMES-UVES spectrograph on the ESO VLT telescope, were analysed using a differential model atmosphere method. Abundances of carbon were derived using spectral synthesis of the C 2 band heads at 5135 and 5635.5{AA}. The wavelength interval 6470-6490{AA}, with CN features, was analysed to determine nitrogen abundances. Oxygen abundances were determined from the [OI] line at 6300{AA}. Abundances of other chemical elements were determined from equivalent widths or spectral syntheses of unblended spectral lines. We provide abundances of up to 29 chemical elements for a sample of 45 giants in NGC 1851. The investigated stars can be separated into two populations with a difference of 0.07dex in the mean metallicity, 0.3dex in the mean C/N, and 0.35 dex in the mean s-process dominated element-to-iron abundance ratios [s/Fe]. No significant difference was determined in the mean values of A(C+N+O) as well as in abundance to iron ratios of carbon, {alpha}- and iron-peak-elements, and of europium. As the averaged A(C+N+O) values between the two populations do not differ, additional evidence is given that NGC 1851 is composed of two clusters, the metal-rich cluster being by about 0.6Gyr older than the metal-poor one. A global overview of NGC 1851 properties and the detailed abundances of chemical elements favour its formation in a dwarf spheroidal galaxy that was accreted by the Milky Way.
- ID:
- ivo://CDS.VizieR/J/AJ/137/4282
- Title:
- Red giant stars in clusters. II. M13 and M92
- Short Name:
- J/AJ/137/4282
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- High-resolution spectra of 123 red giant stars in the globular cluster M13 and 64 red giant stars in M92 were obtained with Hectochelle at the MMT telescope. Emission and line asymmetries in H{alpha} and CaIIK are identified, characterizing motions in the extended atmospheres and seeking differences attributable to metallicity in these clusters and M15. On the red giant branch, emission in H{alpha} generally appears in stars with T_eff_<~4500K and logL/L_{sun}_>~2.75. Fainter stars showing emission are asymptotic giant branch (AGB) stars or perhaps binary stars. The line-bisector for H{alpha} reveals the onset of chromospheric expansion in stars more luminous than log(L/L_{sun}_)~2.5 in all clusters, and this outflow velocity increases with stellar luminosity. However, the coolest giants in the metal-rich M13 show greatly reduced outflow in H{alpha} most probably due to decreased T_eff_ and changing atmospheric structure. The CaIIK_3_ outflow velocities are larger than shown by H{alpha} at the same luminosity and signal accelerating outflows in the chromospheres. Stars clearly on the AGB show faster chromospheric outflows in H{alpha} than RGB objects. While the H{alpha} velocities on the RGB are similar for all metallicities, the AGB stars in the metal-poor M15 and M92 have higher outflow velocities than in the metal-rich M13. Comparison of these chromospheric line profiles in the paired metal-poor clusters, M15 and M92, shows remarkable similarities in the presence of emission and dynamical signatures, and does not reveal a source of the "second-parameter" effect.
- ID:
- ivo://CDS.VizieR/J/A+A/558/A68
- Title:
- Red nuclear spectra of 376 local galaxies
- Short Name:
- J/A+A/558/A68
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We obtained long-slit optical spectra of the nuclear regions of 376 galaxies in the local Universe using the 1.5m Cassini telescope of Bologna Observatory. Of these spectra, 164 were either never taken before by the Sloan Digital Sky Survey (SDSS), or given by the Nasa Extragalactic Database (NED). With these new spectra, we contribute investigating the occurrence of active galactic nuclei (AGNs). Nevertheless, we stress that the present sample is by no means complete, thus, it cannot be used to perform any demographic study. Following the method used in a previous work, we classify the nuclear spectra using a six bin scheme: SEY (Seyfert), sAGN (strong AGN), and wAGN (weak AGN) represent active galactic nuclei of different levels of activity; HII accounts for star-forming nuclei; RET (retired) and PAS (passive) refer to nuclei with poor or no star-formation activity. The spectral classification is performed using the ratio of 6584[NII] to H{alpha} lines and the equivalent width (EW) of H{alpha} versus [NII]/H{alpha} (WHAN diagnostic introduced by Cid Fernandes and collaborators) after correcting H{alpha} for underlying absorption.
