Home News About Us Contact Contributors Disclaimer Privacy Policy Help FAQ

Home
Search
Quick Search
Advanced
Fulltext
Browse
Collections
Persons
My eDoc
Session History
Login
Name:
Password:
Documentation
Help
Support Wiki
Direct access to
document ID:


          Institute: MPI für Astronomie     Collection: Publikationen_mpia     Display Documents



ID: 731696.0, MPI für Astronomie / Publikationen_mpia
Neutron-capture elements across the Galactic thin disk using Cepheids
Authors:da Silva, R.; Lemasle, B.; Bono, G.; Genovali, K.; McWilliam, A.; Cristallo, S.; Bergemann, M.; Buonanno, R.; Fabrizio, M.; Ferraro, I.; François, P.; Iannicola, G.; Inno, L.; Laney, C. D.; Kudritzki, R. -. P.; Matsunaga, N.; Nonino, M.; Primas, F.; Przybilla, N.; Romaniello, M.; Thévenin, F.; Urbaneja, M. A.
Date of Publication (YYYY-MM-DD):2016
Title of Journal:Astronomy and Astrophysics
Volume:586
Start Page:id. A125 (15 pp)
Audience:Not Specified
Abstract / Description:We present new accurate abundances for five neutron-capture elements (Y, La, Ce, Nd, Eu) in 73 classical Cepheids located across the Galactic thin disk. Individual abundances are based on high spectral resolution (R ~ 38 000) and high signal-to-noise ratio (S/N ~ 50-300) spectra collected with UVES at ESO VLT for the DIONYSOS project. Taking into account similar Cepheid abundances provided by our group (111 stars) and available in the literature, we end up with a sample of 435 Cepheids covering a broad range in iron abundances (-1.6 < [Fe/H] < 0.6). We found, via homogeneous individual distances and abundance scales, well-defined gradients for the above elements. However, the slope of the light s-process element (Y) is at least a factor of two steeper than the slopes of heavy s- (La, Ce, Nd) and r- (Eu) process elements. The s-to-r abundance ratio ([La/Eu]) of Cepheids shows a well-defined anticorrelation with both Eu and Fe. On the other hand, Galactic field stars attain an almost constant value and display a mild enhancement in La only when they approach solar iron abundance. The [Y/Eu] ratio shows slight evidence of a correlation with Eu and, in particular, with iron abundance for field Galactic stars. We also investigated the s-process index ([hs/ls]) and we found a well-defined anticorrelation, as expected, between [La/Y] and iron abundance. Moreover, we found a strong correlation between [La/Y] and [La/Fe] and, in particular, a clear separation between Galactic and <ASTROBJ>Sagittarius</ASTROBJ> red giants. Finally, the comparison between predictions for low-mass asymptotic giant branch stars and the observed[La/Y] ratio indicate a very good agreement over the entire metallicity range covered by Cepheids. However, the observed spread at fixed iron content is larger than predicted by current models. Based on spectra collected with the UVES spectrograph available at the ESO Very Large Telescope (VLT), Cerro Paranal, Chile (ESO Proposals: 081.D-0928(A), PI: S. Pedicelli; 082.D-0901(A), PI: S. Pedicelli; 089.D-0767(C), PI: K. Genovali).Tables 2, 3, 4, and 7 are only available at the CDS via anonymous ftp to <A href="http://cdsarc.u-strasbg.fr">http://cdsarc.u-strasbg.fr</A> (ftp://130.79.128.5) or via <A href="http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/586/A125">http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/586/A125</A>
Free Keywords:stars: abundances; stars: variables: Cepheids; stars: oscillations; open clusters and associations: general; Galaxy: disk
External Publication Status:published
Document Type:Article
Communicated by:N. N.
Affiliations:MPI für Astronomie
Identifiers:ISSN:0004-6361
URL:http://cdsads.u-strasbg.fr/abs/2016A%26A...586A.12...
The scope and number of records on eDoc is subject to the collection policies defined by each institute - see "info" button in the collection browse view.