- ID:
- ivo://CDS.VizieR/J/A+A/619/A143
- Title:
- r-process abundances in AMBRE stars
- Short Name:
- J/A+A/619/A143
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The chemical evolution of neutron capture elements in the Milky Way disc is still a matter of debate. There is a lack of statistically significant catalogues of such element abundances, especially those of the r-process. We aim to understand the chemical evolution of r-process elements in Milky Way disc. We focus on three pure r-process elements Eu, Gd, and Dy. We also consider a pure s-process element, Ba, in order to disentangle the different nucleosynthesis processes. We take advantage of high-resolution FEROS, HARPS, and UVES spectra from the ESO archive in order to perform a homogeneous analysis on 6500 FGK Milky Way stars. The chemical analysis is performed thanks to the automatic optimization pipeline GAUGUIN. We present abundances of Ba (5057 stars), Eu (6268 stars), Gd (5431 stars), and Dy (5479 stars). Based on the [{alpha}/Fe] ratio determined previously by the AMBRE Project, we chemically characterize the thin and the thick discs, and a metal-rich {alpha}-rich population. First, we find that the [Eu/Fe] ratio follows a continuous sequence from the thin disc to the thick disc as a function of the metallicity. Second, in thick disc stars, the [Eu/Ba] ratio is found to be constant, while the [Gd/Ba] and [Dy/Ba] ratios decrease as a function of the metallicity. These observations clearly indicate a different nucleosynthesis history in the thick disc between Eu and Gd-Dy. The [r/Fe] ratio in the thin disc is roughly around +0.1dex at solar metallicity, which is not the case for Ba. We also find that the {alpha}-rich metal-rich stars are also enriched in r-process elements (like thick disc stars), but their [Ba/Fe] is very different from thick disc stars. Finally, we find that the [r/{alpha}] ratio tends to decrease with metallicity, indicating that supernovae of different properties probably contribute differently to the synthesis of r-process elements and {alpha}-elements. We provide average abundance trends for [Ba/Fe] and [Eu/Fe] with rather small dispersions, and for the first time for [Gd/Fe] and [Dy/Fe]. This data may help to constrain chemical evolution models of Milky Way r- and s-process elements and the yields of massive stars. We emphasize that including yields of neutron-star or black hole mergers is now crucial if we want to quantitatively compare observations to Galactic chemical evolution models.
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Search Results
- ID:
- ivo://CDS.VizieR/J/AJ/159/145
- Title:
- RVs and opt. photometry of the host star TOI-677
- Short Name:
- J/AJ/159/145
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report the discovery of TOI-677b, first identified as a candidate in light curves obtained within Sectors 9 and 10 of the Transiting Exoplanet Survey Satellite (TESS) mission and confirmed with radial velocities. TOI-677b has a mass of M_p_=1.236_-0.067_^+0.069^M_J_, a radius of R_P_=1.170{+/-}0.03R_J_, and orbits its bright host star (V=9.8mag) with an orbital period of 11.23660{+/-}0.00011d, on an eccentric orbit with e=0.435{+/-}0.024. The host star has a mass of M_*_=1.181{+/-}0.058M_{sun}_, a radius of R_*_=1.28_-0.03_^+0.03^R_{sun}_, an age of 2.92_-0.73_^+0.80^Gyr and solar metallicity, properties consistent with a main-sequence late-F star with T_eff_=6295{+/-}77K. We find evidence in the radial velocity measurements of a secondary long-term signal, which could be due to an outer companion. The TOI-677b system is a well-suited target for Rossiter-Mclaughlin observations that can constrain migration mechanisms of close-in giant planets.
- ID:
- ivo://CDS.VizieR/J/ApJ/738/122
- Title:
- ScoCen debris disks Around F- and G-type stars
- Short Name:
- J/ApJ/738/122
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We obtained Spitzer Space Telescope Multiband Imaging Photometer for Spitzer (MIPS) 24 micron and 70 micron observations of 182 nearby, Hipparcos F- and G-type common proper motion single and binary systems in the nearest OB association, Scorpius-Centaurus. We also obtained Magellan/MIKE R~50,000 visual spectra at 3500-10500{AA} for 181 candidate ScoCen stars in single and binary systems. Combining our MIPS observations with those of other ScoCen stars in the literature, we estimate 24 micron F+G-type disk fractions of 9/27 (33%+/-11%), 21/67 (31%+/-7%), and 25/71 (35%+/-7%) for Upper Scorpius (~10Myr), Upper Centaurus Lupus (~15Myr), and Lower Centaurus Crux (~17Myr), respectively. We confirm previous IRAS and MIPS excess detections and present new discoveries of 41 protoplanetary and debris disk systems, with fractional infrared luminosities ranging from L_IR/L_*=10^-5^ to 1.0^-2^ and grain temperatures ranging from T_gr_=40-300K. We searched for an increase in 24 micron excess at an age of 15-20Myr, consistent with the onset of debris production predicted by coagulation N-body simulations of outer planetary systems. We found such an increase around 1.5M_{sun}_ stars but discovered a decrease in the 24 micron excess around 1.0M_{sun}_ stars. We additionally discovered that the 24 micron excess around 1.0M_{sun}_ stars is larger than predicted by self-stirred models. Finally, we found a weak anti-correlation between fractional infrared luminosity (L_IR/L_*) and chromospheric activity (R'_HK), that may be the result of differences in stellar HK properties, such as mass, luminosity, and/or winds. We obtained Spitzer Space Telescope Multiband Imaging Photometer for Spitzer (MIPS) 24 micron and 70 micron observations of 182 nearby, Hipparcos F- and G-type common proper motion single and binary systems in the nearest OB association, Scorpius-Centaurus. We also obtained Magellan/MIKE R~50,000 visual spectra at 3500-10500{AA} for 181 candidate ScoCen stars in single and binary systems. Combining our MIPS observations with those of other ScoCen stars in the literature, we estimate 24 micron F+G-type disk fractions of 9/27 (33%+/-11%), 21/67 (31%+/-7%), and 25/71 (35%+/-7%) for Upper Scorpius (~10Myr), Upper Centaurus Lupus (~15Myr), and Lower Centaurus Crux (~17Myr), respectively. We confirm previous IRAS and MIPS excess detections and present new discoveries of 41 protoplanetary and debris disk systems, with fractional infrared luminosities ranging from L_IR/L_* = 10^-5^ to 10^-2^ and grain temperatures ranging from T_gr_=40-300K. We searched for an increase in 24 micron excess at an age of 15-20Myr, consistent with the onset of debris production predicted by coagulation N-body simulations of outer planetary systems. We found such an increase around 1.5M_{sun}_ stars but discovered a decrease in the 24 micron excess around 1.0M_{sun}_ stars. We additionally discovered that the 24 micron excess around 1.0M_{sun}_ stars is larger than predicted by self-stirred models.
- ID:
- ivo://CDS.VizieR/J/ApJ/725/2017
- Title:
- Sloan i-band light curve of HAT-P-24
- Short Name:
- J/ApJ/725/2017
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report the discovery of HAT-P-24b, a transiting extrasolar planet orbiting the moderately bright V=11.818 F8 dwarf star GSC 0774-01441, with a period P=3.3552464+/-0.0000071 days, transit epoch T_c_=2455216.97669+/-0.00024(BJD), and transit duration 3.653+/-0.025hr. The host star has a mass of 1.191+/-0.042M_{sun}_, radius of 1.317+/-0.068R_{sun}_, effective temperature 6373+/-80K, and a low metallicity of [Fe/H]=-0.16+/-0.08. The planetary companion has a mass of 0.681+/-0.031M_J_ and radius of 1.243+/-0.072R_J_ yielding a mean density of 0.439+/-0.069g/cm^3^. By repeating our global fits with different parameter sets, we have performed a critical investigation of the fitting techniques used for previous Hungarian-made Automated Telescope planetary discoveries. We find that the system properties are robust against the choice of priors.
- ID:
- ivo://CDS.VizieR/J/A+A/651/A11
- Title:
- SOPHIE radial velocities of 27 F/G stars
- Short Name:
- J/A+A/651/A11
- Date:
- 22 Feb 2022
- Publisher:
- CDS
- Description:
- Distinguishing classes within substellar objects and understanding their formation and evolution need larger samples of substellar companions such as exoplanets, brown dwarfs, and low-mass stars. In this paper, we look for substellar companions using radial velocity surveys of FGK stars with the SOPHIE spectrograph at the Observatoire de Haute-Provence. We assign here the radial velocity variations of 27 stars to their orbital motion induced by low-mass companions. We also constrained their plane-of-the-sky motion using HIPPARCOS and Gaia Data Release 1 measurements, which constrain the true masses of some of these companions. We report the detection and characterization of six cool Jupiters, three brown dwarf candidates, and 16 low-mass stellar companions. We additionally update the orbital parameters of the low-mass star HD 8291 B, and we conclude that the radial velocity variations of HD 204277 are likely due to stellar activity despite resembling the signal of a giant planet. One of the new giant planets, BD+631405 b, adds to the population of highly eccentric cool Jupiters, and it is presently the most massive member. Two of the cool Jupiter systems also exhibit signatures of an additional outer companion. The orbital periods of the new companions span 30 days to 11.5 years, their masses 0.72M_Jup_ to 0.61M_{sun}_, and their eccentricities 0.04 to 0.88. These discoveries probe the diversity of substellar objects and low-mass stars, which will help constrain the models of their formation and evolution.
- ID:
- ivo://CDS.VizieR/J/PAZh/30/173
- Title:
- Space velocities of solar neighborhood stars
- Short Name:
- J/PAZh/30/173
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- For 77 main-sequence F-G stars in the solar neighborhood with published iron, magnesium, and europium abundances and with the ages we calculated the spatial velocities using Hipparcos data and the galactic orbital elements. A comparison with the orbital elements of the globular clusters that are known to have been accreted by our Galaxy in the past reveals stars of the extragalactic origin. We show that the abundance ratios of r- and {alpha}-elements in all the accreted stars differ sharply from those in the stars that are genetically associated with the Galaxy.
- ID:
- ivo://CDS.VizieR/J/AJ/160/52
- Title:
- Spectral classification for 631 {rho}Puppis stars
- Short Name:
- J/AJ/160/52
- Date:
- 09 Mar 2022
- Publisher:
- CDS
- Description:
- The {rho}Puppis stars are mid-F-type stars that show peculiar chemical-abundance patterns similar to those of the Am stars. Typically they exhibit overabundances of iron-peak elements such as Fe and Ni and s- and r-process elements such as Sr and Eu, and underabundances of certain other elements including He, Ca, and Sc. It has been proposed that these stars are evolving Am stars passing through the short-lived phase that occurs between the re-establishment of convection and the consequent erasure of their chemical peculiarities. In this paper we suggest a second hypothesis: these stars may have acquired their peculiar abundance patterns in a fashion similar to the Barium stars, i.e., they may have gained the s-process element enhancements via mass transfer from a once asymptotic giant-branch companion star, now turned white dwarf. This study will detail our efforts to investigate the {rho}Puppis stars with regard to these two hypotheses, with a view to understanding these stars and their significance in terms of stellar evolution. We have performed a spectral classification survey, and a detailed chemical-abundance analysis of selected {rho}Puppis stars. This paper gives an overview of the {rho}Puppis stars and describes the spectral classification survey which has increased the number of {rho}Puppis stars currently known from 6 to 49. A future paper will describe the chemical-abundance analysis which should provide insight into the nature of these stars.
- ID:
- ivo://CDS.VizieR/J/AJ/144/135
- Title:
- Spitzer 24{mu}m photometry of Hipparcos F stars
- Short Name:
- J/AJ/144/135
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have conducted a study of debris disks around F stars in order to explore correlations between rotation, stellar winds, and circumstellar disks. We obtained new 24{mu}m photometry from the Multiband Imaging Photometer for Spitzer (MIPS) camera for a sample of 188 relatively nearby F dwarfs with various rotation rates and optical colors, and combined it with archival MIPS data for 66 more F stars, as well as Wide-field Infrared Survey Explorer data for the entire sample, plus 9 more F stars. Based on the objects' K_s_-[24] and [3.4]-[22] colors, we identify 22 stars in our sample as having 22 and/or 24{mu}m excesses above our detection limit, 13 of which are new discoveries. Our overall disk detection rate is 22/263, or 8%, consistent with previous determinations of disk fractions in the solar neighborhood. While fast-rotating stars are expected to have strong winds capable of efficiently removing dust, we find no correlation between rotational velocity and infrared excess. Similarly, we find no significant difference in excess detection rate between late-type F stars, which have convective surfaces, and early-type F stars, which have fully radiative envelopes. However, the essentially unknown range of ages in this sample may be washing out any effects relating rotation, winds, and disks.
- ID:
- ivo://CDS.VizieR/J/A+AS/106/257
- Title:
- Stroemgren photometry of F and G stars
- Short Name:
- J/A+AS/106/257
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- (no description available)
- ID:
- ivo://CDS.VizieR/J/ApJ/622/1102
- Title:
- The planet-metallicity correlation.
- Short Name:
- J/ApJ/622/1102
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have recently carried out spectral synthesis modeling to determine T_eff_, log(g), vsin(i), and [Fe/H] for 1040 FGK-type stars on the Keck, Lick, and Anglo-Australian Telescope planet search programs. This is the first time that a single, uniform spectroscopic analysis has been made for every star on a large Doppler planet search survey. We identify a subset of 850 stars that have Doppler observations sufficient to detect uniformly all planets with radial velocity semiamplitudes K>30m/s and orbital periods shorter than 4yr.
