- ID:
- ivo://CDS.VizieR/J/MNRAS/415/563
- Title:
- Elemental abundances in Hyades supercluster
- Short Name:
- J/MNRAS/415/563
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The existence of a kinematically defined moving group of stars centred at U=-40, V=-17km/s, referred to as the Hyades supercluster, has been suggested to be the debris of an originally large star-forming event, with its core being the present-day Hyades open cluster. Using high-resolution UV-Visual Echelle Spectrograph (UVES) spectra, we present the elemental abundances for a range of alpha, Fe-peak and neutron-capture elements for 26 proposed supercluster stars. Our results show that the sample stars display a heterogeneous abundance distribution, with a clump around [Fe/H]=+0.15. We also calculate stellar radial velocities and U, V, W space velocities. Enforcing strict chemical and kinematical membership criteria, we find that four supercluster stars share the Hyades open cluster abundances and kinematics, while many of the remaining stars fit the disc field kinematics and abundance range. We discuss our findings in the context of the Hyades supercluster being a dispersed star-forming remnant, a stellar stream of purely dynamical origin or a result of several processes.
Number of results to display per page
Search Results
- ID:
- ivo://CDS.VizieR/J/MNRAS/386/2039
- Title:
- Elemental abundances of {alpha} Cir
- Short Name:
- J/MNRAS/386/2039
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have used the Sydney University Stellar Interferometer to measure the angular diameter of alpha Cir. This is the first detailed interferometric study of a rapidly oscillating A (roAp) star, alpha Cir being the brightest member of its class. We used the new and more accurate Hipparcos parallax to determine the radius to be 1.967+/-0.066R_{sun}_. We have constrained the bolometric flux from calibrated spectra to determine an effective temperature of 7420+/-170K . This is the first direct determination of the temperature of an roAp star. Our temperature is at the low end of previous estimates, which span over 1000K and were based on either photometric indices or spectroscopic methods. In addition, we have analysed two high-quality spectra of alpha Cir, obtained at different rotational phases and we find evidence for the presence of spots.
- ID:
- ivo://CDS.VizieR/J/A+A/420/673
- Title:
- Elemental abundances of CP2 star HR 5049
- Short Name:
- J/A+A/420/673
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A spectrum synthesis analysis for photospheric lines in the magnetic B star HR 5049 is presented, based on a high quality spectrogram obtained with the EMMI spectrograph attached to the NTT at ESO. It is found that light elements such as He, C and O are under-abundant. One of the most notable features is the deficiency of He by more than -2.0dex. Co and Cl are over-abundant by +3.5dex and +1.9dex, respectively. Other iron peak elements are over-abundant ranging from +0.47dex (Ti II) to +1.94 dex (Cr I). For rare earth elements, the lines of once-ionized species are generally weak, while the third spectra (especially those of Pr and Nd) are very prominent. Although rare earth elements show significant over-abundances ranging from +3.0dex to as large as +4.0dex, Ba has the solar abundance. The Nd-Pr abundance difference, which shows an apparent decreasing trend with increasing effective temperature among CP stars, is found to be unusually small in HR 5049.
- ID:
- ivo://CDS.VizieR/J/A+A/364/237
- Title:
- Elemental abundances of Deneb
- Short Name:
- J/A+A/364/237
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This study presents a detailed model atmosphere abundance analysis of Deneb which was performed using Kurucz LTE ATLAS9 model atmospheres. The atmospheric parameters were determined from Mg I/II and Fe I/II equilibrium, and by fitting the H{gamma} profile and optical region spectrophotometry. The compromise values which best satisfy these criteria are T_eff_ = 9000 K and log g = 1.45. The Mg I, Mg II, Si II, Ti II, Cr II, Fe I, and Fe II lines yield microturbulences of 3.60, 6.50, 8.50, 8.00, 11.90, 3.60, and 10.40 km/s, respectively. An average microturbulence of 7 km/s was used for the other atomic species.
- ID:
- ivo://CDS.VizieR/J/AJ/130/1111
- Title:
- Elemental abundances of field red giants
- Short Name:
- J/AJ/130/1111
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We summarize a selection process to identify red giants in the direction of the southern warp of the Galactic disk, employing VI_C_ photometry and multi-object spectroscopy.
- ID:
- ivo://CDS.VizieR/J/A+A/406/975
- Title:
- Elemental abundances of four A-B stars
- Short Name:
- J/A+A/406/975
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The superficially normal stars {theta} And (A2 V), {epsilon} Del (B6 III), {epsilon} Aqr (A1.5 V), and {iota} And (B9 V), which have rotationally broadened line profiles, are analyzed in a manner consistent with previous studies of this series using 2.4{AA}/mm spectrograms obtained with CCD detectors and S=N>=200. Their variable radial velocities strongly suggest they are spectroscopic binaries. As no evidence is seen for lines of their companions they are analyzed as single stars. Their derived abundances are generally near solar. But those for {theta} And suggest that it is possibly a fast rotating Am star.
- ID:
- ivo://CDS.VizieR/J/AJ/155/68
- Title:
- Elemental abundances of KOIs in APOGEE. I.
- Short Name:
- J/AJ/155/68
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Apache Point Observatory Galactic Evolution Experiment (APOGEE) has observed ~600 transiting exoplanets and exoplanet candidates from Kepler (Kepler Objects of Interest, KOIs), most with >=18 epochs. The combined multi-epoch spectra are of high signal-to-noise ratio (typically >=100) and yield precise stellar parameters and chemical abundances. We first confirm the ability of the APOGEE abundance pipeline, ASPCAP, to derive reliable [Fe/H] and effective temperatures for FGK dwarf stars - the primary Kepler host stellar type - by comparing the ASPCAP-derived stellar parameters with those from independent high-resolution spectroscopic characterizations for 221 dwarf stars in the literature. With a sample of 282 close-in (P<100 days) KOIs observed in the APOGEE KOI goal program, we find a correlation between orbital period and host star [Fe/H] characterized by a critical period, P_crit_=8.3_-4.1_^+0.1^ days, below which small exoplanets orbit statistically more metal-enriched host stars. This effect may trace a metallicity dependence of the protoplanetary disk inner radius at the time of planet formation or may be a result of rocky planet ingestion driven by inward planetary migration. We also consider that this may trace a metallicity dependence of the dust sublimation radius, but we find no statistically significant correlation with host T_eff_ and orbital period to support such a claim.
- ID:
- ivo://CDS.VizieR/J/BaltA/14/51
- Title:
- Elemental abundances of 4 Lac and nu Cep
- Short Name:
- J/BaltA/14/51
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Elemental abundance analysis based on high S/N and high resolution Dominion Astrophysical Observatory spectrograms have been performed for two early type supergiants: 4 Lac (B9 Iab) and {nu} Cep (A2 Ia). Lines as weak as of order 5m{AA} are employed in this study. The projected rotational velocities of these stars are 14 and 26km/s, respectively. Both stars show similar radial velocity amplitudes, macroturbulent velocities and the same general elemental abundance trends. Their He, CNO and light element abundances are solar or overabundant while the iron peak and heavy element abundances are solar or underabundant. Detailed LTE model atmosphere abundance analysis shows that 4 Lac has nuclearly processed matter in its photosphere while {nu} Cep does not.
- ID:
- ivo://CDS.VizieR/J/AJ/127/373
- Title:
- Elemental abundances of 3 red giants in Ter 7
- Short Name:
- J/AJ/127/373
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Chemical abundances in three giants in Terzan 7, a globular cluster associated with the Sagittarius dwarf galaxy, have been determined using high-resolution spectra obtained with the UVES spectrograph on the ESO 8.2m Kueyen telescope. We find the overall metallicity of the stars to be [Fe/H]=-0.61+/-0.07, which is slightly higher than that previously evaluated from photometry and used for the age determination of this cluster. This metallicity yields an age of about 6Gyr, which is slightly lower than derived from previous estimates. The relative abundance ratios of various chemical elements to iron lie between those of its host galaxy's metal-poor and metal-rich stars and reveal an intriguing similarity to the pattern seen in the Large Magellanic Cloud.
- ID:
- ivo://CDS.VizieR/J/ApJ/787/154
- Title:
- Elemental abundances of solar sibling candidates
- Short Name:
- J/ApJ/787/154
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Dynamical information along with survey data on metallicity and in some cases age have been used recently by some authors to search for candidates of stars that were born in the cluster where the Sun formed. We have acquired high-resolution, high signal-to-noise ratio spectra for 30 of these objects to determine, using detailed elemental abundance analysis, if they could be true solar siblings. Only two of the candidates are found to have solar chemical composition. Updated modeling of the stars' past orbits in a realistic Galactic potential reveals that one of them, HD 162826, satisfies both chemical and dynamical conditions for being a sibling of the Sun. Measurements of rare-element abundances for this star further confirm its solar composition, with the only possible exception of Sm. Analysis of long-term high-precision radial velocity data rules out the presence of hot Jupiters and confirms that this star is not in a binary system. We find that chemical tagging does not necessarily benefit from studying as many elements as possible but instead from identifying and carefully measuring the abundances of those elements that show large star-to-star scatter at a given metallicity. Future searches employing data products from ongoing massive astrometric and spectroscopic surveys can be optimized by acknowledging this fact.