| Title: |
HD 65949: Rosetta stone or red herring ★ |
| Authors: |
Cowley, C. R.; Hubrig, S.; Palmeri, P.; Quinet, P.; Biémont, É.; Wahlgren, G. M.; Schütz, O.; González, J. F. |
| Contributors: |
Department of Astronomy, University of Michigan, Ann Arbor, MI 48109-1042, USA; Astrophysikalisches Institut Potsdam, An der Sternwarte 16, 14482 Potsdam, Germany; Astrophysique et Spectroscopie, Université de Mons-UMONS, B-7000 Mons, Belgium; IPNAS, Université de Liège, Sart Tilman B15, B-4000 Liège, Belgium; Catholic University of America, 620 Michigan Avenue NE, Washington, DC 20064, USA; NASA Goddard Space Flight Center, Code 667, Greenbelt, MD 20771, USA; European Southern Observatory, Casilla 19001, Santiago 19, Chile; Instituto de Ciencias Astronómicas, de la Tierra y del Espacio, Casilla 49, 5400 San Juan, Argentina |
| Publisher Information: |
Blackwell Publishing Ltd |
| Publication Year: |
2010 |
| Collection: |
University of Michigan: Deep Blue |
| Subject Terms: |
Astrochemistry; Diffusion; Stars: Abundances; Stars: Chemically Peculiar; Stars: Individual: HD 65949; Stars: Individual: HR 7143; Astronomy; Science |
| Description: |
HD 65949 is a late B star with exceptionally strong Hg ii λ 3984, but it is not a typical HgMn star. The Re ii spectrum is of extraordinary strength. Abundances or upper limits are derived here for 58 elements based on a model with T eff = 13 100 K and log ( g ) = 4.0 . Even- Z elements through nickel show minor deviations from solar abundances. Anomalies among the odd- Z elements through copper are mostly small. Beyond the iron peak, a huge scatter is found. Enormous enhancements are found for the elements rhenium through mercury ( Z = 75 –80). We note the presence of Th iii in the spectrum. The abundance pattern of the heaviest elements resembles the N = 126 r-process peak of solar material, though not in detail. An odd- Z anomaly appears at the triplet (Zr Nb Mo), and there is a large abundance jump between Xe ( Z = 54 ) and Ba ( Z = 56 ). These are signatures of chemical fractionation.We find a significant correlation of the abundance excesses with second ionization potentials for elements with Z > 30 . If this is not a red herring (false lead), it indicates the relevance of photospheric or near-photospheric processes. Large excesses (4–6 dex) require diffusion from deeper layers with the elements passing through a number of ionization stages. That would make the correlation with second ionization potential puzzling. We explore a model with mass accretion of exotic material followed by the more commonly accepted differentiation by diffusion. That model leads to a number of predictions which challenge future work.New observations confirm the orbital elements of Gieseking and Karimie, apart from the systemic velocity, which has increased. Likely primary and secondary masses are near 3.3 and 1.6 M ⊙ , with a separation of ca. 0.25 au.New atomic structure calculations are presented in two appendices. These include partition functions for the first through third spectra of Ru, Re and Os, as well as oscillator strengths in the Re ii spectrum. ; Peer Reviewed ... |
| Document Type: |
article in journal/newspaper |
| File Description: |
932967 bytes; 3106 bytes; application/pdf; text/plain |
| Language: |
unknown |
| Relation: |
http://hdl.handle.net/2027.42/79106; Monthly Notices of the Royal Astronomical Society |
| DOI: |
10.1111/j.1365-2966.2010.16529.x |
| Availability: |
http://hdl.handle.net/2027.42/79106; https://doi.org/10.1111/j.1365-2966.2010.16529.x |
| Rights: |
IndexNoFollow |
| Accession Number: |
edsbas.FAC6A548 |
| Database: |
BASE |