- ID:
- ivo://CDS.VizieR/J/AJ/159/9
- Title:
- HD 150382 lithium-rich star at the early-AGB stage
- Short Name:
- J/AJ/159/9
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report the discovery of a lithium-rich giant, HD 150382, a post-red-giant-branch clump star. The atmospheric parameters, the chemical abundances for 17 elements, and the isotopic ratio ^12^C/^13^C were determined using the equivalent width and the spectral synthesis methods. The lithium abundance was determined via spectral synthesis of the Li I resonance doublet at {lambda} 6708 yielding log{epsilon}(Li)_NLTE_=2.55. The excited-state line at {lambda} 6104 also was analyzed. In addition, we have used theoretical evolutionary tracks to determine the mass and luminosity of HD 150382 and compare it with other well-known lithium-rich giants in the literature. Our results show that HD 150382 is a slowly rotating K-giant star having near-solar metallicity. We also show that HD 150382 is not s-process enriched, which is in agreement with its evolutionary status. Finally, based on the abundance results, we study the possible scenarios of the lithium enrichment.
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- ID:
- ivo://CDS.VizieR/J/A+A/333/205
- Title:
- HD 185510 UBV photometry
- Short Name:
- J/A+A/333/205
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- UBV photometry and moderate resolution H{alpha} spectrophotometry of the evolved binary system HD 185510 (sdB + K0 III), performed at Catania Astrophysical Observatory, is presented and discussed. The spectrophotometric data were collected in 1991, 1993, and 1994, while the photometric light curves were obtained in 1993, 1994 and 1995. From the B and V photometry we determine a new photometric rotational period of 26.23d, confirming the asynchronous rotation of the cool giant component. The spectroscopic data confirm the vsin i value of 15km/s measured by Fekel et al. (1993AJ....106.2370F) and clearly reveal a filled-in H{alpha} line with appreciable variations. The excess emission of the line, observed at any orbital phase, is found to be anticorrelated with the V light curve and is primarily ascribed to the chromospheric activity on the cool star. The primary total eclipse is clearly visible in the U band, but undetectable in the V band. From the U observations we determined a total duration of the primary eclipse (from 1^st^ to 4^rd^ contact) of 1.3883d, with the ingress lasting only 27 minutes. This new accurate monitoring and timing of the eclipse allowed us to improve the system solution which leads to R_C_=8.8R_{sun}_, T_C_=4800K, R_H_=0.11R_{sun}_, T_H_=30000K for the cool and hot star respectively. The evolution of HD 185510B is discussed also in relation to the evolutionary status of HD 185510A and the synchronization time scale. HD 185510B is probably a sdB near the zero age extended horizontal branch, resulting from an enhanced mass loss in late case B or case A mass exchange with a possible common envelope phase. A small amount (15-20%) of mass loss from the system which can account for the strong IR excess is suggested.
- ID:
- ivo://CDS.VizieR/J/A+A/569/A43
- Title:
- HE 2252-4225 abundance analysis
- Short Name:
- J/A+A/569/A43
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Studies of the r-process enhanced stars are important for better understanding the nature and origin of the r-process. We present a detailed abundance analysis of a very metal-poor giant star discovered in the HERES project, HE 2252-4225, which exhibits overabundances of the r-process elements, with [r/Fe]=+0.80. We determined the stellar atmosphere parameters, Teff=4710K, logg=1.65, and [Fe/H]=-2.63, and chemical abundances by analysing the high-quality VLT/UVES spectra. The surface gravity was calculated from the non-local thermodynamic equilibrium (NLTE) ionisation balance between FeI and FeII. Accurate abundances for a total of 38 elements, including 22 neutron-capture elements beyond Sr and up to Th, were determined in HE 2252-4225. For every chemical species, the dispersion in the single line measurements around the mean does not exceed 0.12dex. This object is deficient in carbon, as expected for a giant star with Teff<4800K. The stellar Na-Zn abundances are well fitted by the yields of a single supernova of 14.4M_{sun}_. For the neutron-capture elements in the Sr-Ru, Ba-Yb, and Os-Ir regions, the abundance pattern of HE 2252-4225 is in excellent agreement with the average abundance pattern of the strongly r-process enhanced stars CS 22892-052, CS 31082-001, HE 1219-0312, and HE 1523-091. This suggests a common origin of the first, second, and third r-process peak elements in HE 2252-4225 in the classical r-process. We tested the solar r-process pattern based on the most recent s-process calculations of Bisterzo, Travaglio, Gallino, Wiescher, and Kappeler and found that elements in the range from Ba to Ir match it very well. No firm conclusion can be drawn about the relationship between the first neutron-capture peak elements, Sr to Ru, in HE 2252-4225 and the solar r-process, due to the uncertainty in the solar r-process. The investigated star has an anomalously high Th/Eu abundance ratio, so that radioactive dating results in a stellar age of {tau}=1.5+/-1.5Gyr that is not expected for a very metal-poor halo star.
- ID:
- ivo://CDS.VizieR/J/A+A/516/A46
- Title:
- HE 2327-5642 abundance analysis
- Short Name:
- J/A+A/516/A46
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a detailed abundance analysis of a strongly r-process enhanced giant star discovered in the HERES project, HE 2327-5642, for which [Fe/H]=-2.78, [r/Fe]=+0.99 [r = elements from r-process]. We determined the stellar parameters and element abundances by analyzing the high-quality VLT/UVES spectra. The surface gravity was calculated from the non-local thermodynamic equilibrium (NLTE) ionization balance between FeI, and FeII, and CaI and CaII.
- ID:
- ivo://CDS.VizieR/J/ApJ/689/1031
- Title:
- Heavy element abundances in giant stars
- Short Name:
- J/ApJ/689/1031
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a comprehensive abundance analysis of 27 heavy elements in bright giant stars of the globular clusters M4 and M5 based on high-resolution, high signal-to-noise ratio spectra obtained with the Magellan Clay Telescope. We confirm and expand on previous results for these clusters by showing that (1) all elements heavier than, and including, Si have constant abundances within each cluster, (2) the elements from Ca to Ni have indistinguishable compositions in M4 and M5, (3) Si, Cu, Zn, and all s-process elements are approximately 0.3dex overabundant in M4 relative to M5, and (4) the r-process elements Sm, Eu, Gd, and Th are slightly overabundant in M5 relative to M4. The cluster-to-cluster abundance differences for Cu and Zn are intriguing, especially in light of their uncertain nucleosynthetic origins. We confirm that stars other than Type Ia supernovae must produce significant amounts of Cu and Zn at or below the clusters' metallicities. If intermediate-mass AGB stars or massive stars are responsible for the Cu and Zn enhancements in M4, the similar [Rb/Zr] ratios and (preliminary) Mg isotope ratios in both clusters may be problematic for either scenario. For the elements from Ba to Hf, we assume that the s- and r-process contributions are scaled versions of the solar s- and r-process abundances. We quantify the relative fractions of s- and r-process material for each cluster and show that they provide an excellent fit to the observed abundances.
- ID:
- ivo://CDS.VizieR/J/ApJ/724/975
- Title:
- Heavy elements abundances of metal-poor stars
- Short Name:
- J/ApJ/724/975
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- To better characterize the abundance patterns produced by the r-process, we have derived new abundances or upper limits for the heavy elements zinc (Zn, Z=30), yttrium (Y, Z=39), lanthanum (La, Z=57), europium (Eu, Z=63), and lead (Pb, Z=82). Our sample of 161 metal-poor stars includes new measurements from 88 high-resolution and high signal-to-noise spectra obtained with the Tull Spectrograph on the 2.7m Smith Telescope at the McDonald Observatory, and other abundances are adopted from the literature. We use models of the s-process in asymptotic giant branch stars to characterize the high Pb/Eu ratios produced in the s-process at low metallicity, and our new observations then allow us to identify a sample of stars with no detectable s-process material.
- ID:
- ivo://CDS.VizieR/J/MNRAS/460/1356
- Title:
- Hercules stream K giants analysis
- Short Name:
- J/MNRAS/460/1356
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- An abundance analysis is reported of 58-K giants identified by Famaey et al. (2005, J/A+A/430/165) as highly probable members of the Hercules stream selected from stars north of the celestial equator in the Hipparcos catalogue. The giants have compositions spanning the interval [Fe/H] from -0.17 to +0.42 with a mean value of +0.15 and relative elemental abundances [El/Fe] representative of the Galactic thin disc. Selection effects may have biased the selection from the Hipparcos catalogue against the selection of metal-poor stars. Our reconsideration of the recent extensive survey by Bensby et al. of FG dwarfs, including metal-poor stars, provides a [Fe/H] distribution for the Hercules stream, which is similar to that from the 58 giants. It appears that the stream is dominated by metal-rich stars from the thin disc. We discuss suggestions in the literature that the stream includes metal-poor stars from the thick disc.
- ID:
- ivo://CDS.VizieR/J/A+A/570/A113
- Title:
- Herschel/PACS imaging of {pi}^1^ Gru (HIP110478)
- Short Name:
- J/A+A/570/A113
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Mass loss of Evolved StarS (MESS) sample observed with PACS on board the Herschel Space Observatory revealed that several asymptotic giant branch (AGB) stars are surrounded by an asymmetric circumstellar envelope (CSE) whose morphology is most likely caused by the interaction with a stellar companion. The evolution of AGB stars in binary systems plays a crucial role in understanding the formation of asymmetries in planetary nebulae (PNe), but at present, only a handful of cases are known where the interaction of a companion with the stellar AGB wind is observed. We probe the environment of the very evolved AGB star pi^1^ Gruis on large and small scales to identify the triggers of the observed asymmetries.
- ID:
- ivo://CDS.VizieR/J/AJ/143/128
- Title:
- High-metallicity M giant candidates from SDSS
- Short Name:
- J/AJ/143/128
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Tidal stripping and three-body interactions with the central supermassive black hole may eject stars from the Milky Way. These stars would comprise a set of "intragroup" stars (IGS) that trace the past history of interactions in our galactic neighborhood. Using the Sloan Digital Sky Survey (SDSS) DR7 (Cat. II/294, superseded by Cat. V/139), we identify candidate solar-metallicity red giant intragroup stars using color cuts that are designed to exclude nearby M and L dwarfs. We present 677 intragroup candidates that are selected between 300kpc and 2Mpc, and are either the reddest intragroup candidates (M7-M10) or are L dwarfs at larger distances than previously detected.
- ID:
- ivo://CDS.VizieR/J/AZh/83/158
- Title:
- High precision effective temperatures of giants
- Short Name:
- J/AZh/83/158
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The spectral lines of high and low excitation potentials respond differently to the change in effective temperature (Teff). Therefore, the ratio of their depths (or equivalent widths) is a very sensitive temperature indicator. A set of 100 relations is obtained which rely Teff on line depth ratios, calibrated against previously published precise (one per cent) temperature estimates of giants. Highly precise temperatures have been determined from this relations for a set of 110 giants of about solar metallicity, based on high resolution (R=42000), high S/N echelle spectra. The application range of the calibrations is 4000-7000K (F2III-K4III). The internal error of a single calibration is less than 95K, while the combination of all calibrations for a spectrum of S/N=100 reduces uncertainty to only 5-25K (1{sigma}). The big advantage of using line-depth ratios is the independence on the interstellar reddening, spectral resolution, rotational and microturbulence broadening.
