Accretion of chemically fractionated material on a wide binary with a blue straggler

Abstract

The components of the wide binary HIP64030=HD 113984 show a large (about 0.25 dex) iron content difference (Desidera et al.~2006 A&A 454, 581). The positions of the components on the color magnitude diagram suggest that the primary is a blue straggler. We studied the abundance difference of several elements besides iron, and we searched for stellar and substellar companions around the components to unveil the origin of the observed iron difference. A line-by-line differential abundance analysis for several elements was performed, while suitable spectral synthesis was performed for C, N, and Li. High precision radial velocities obtained with the iodine cell were combined with available literature data. The analysis of additional elements shows that the abundance difference for the elements studied increases with increasing condensation temperature, suggesting that accretion of chemically fractionated material might have occurred in the system. Alteration of C and N likely due to CNO processing is also observed. We also show that the primary is a spectroscopic binary with a period of 445 days and moderate eccentricity. The minimum mass of the companion is 0.17 Msun. Two scenarios were explored to explain the observed abundance pattern. In the first, all abundance anomalies arise on the blue straggler. If this is the case, the dust-gas separation may have been occurred in a circumbinary disk around the blue straggler and its expected white dwarf companion, as observed in several RV Tauri and post AGB binaries. In the second scenario, accretion of dust-rich material occurred on the secondary. This would also explain the anomalous carbon isotopic ratio of the secondary. Such a scenario requires that a substantial amount of mass lost by the central binary has been accreted by the wide component.

References in corpus (20)

• Evolution of binary stars and the effect of tides on binary populations
• The Geneva-Copenhagen survey of the Solar neighbourhood: Ages, metallicities, and kinematic properties of 14,000 F and G dwarfs
• Abundances for metal-poor stars with accurate parallaxes I. Basic data
• Detection Limits from the McDonald Observatory Planet Search Program
• Keplerian discs around post-AGB stars: a common phenomenon?
• Double Core Evolution X. Through the Envelope Ejection Phase
• Stellar Archaeology: a Keck Pilot Program on Extremely Metal- Poor Stars From the Hamburg/ESO Survey. III. The Lead (Pb) Star HE 0024-2523
• On the Formation and Evolution of Common Envelope Systems
• Wind accretion in binary stars II. Accretion rates
• Abundance differences between components of wide binaries
• Abundance Analyses of Field RV Stars, V: DS Aquarii, UY Arae, TW Camelopardis, BT Librae, U Moncerotis, TT Ophiuchi, and RV Tauri
• Metal-poor Field Blue Stragglers: More Evidence for Mass Transfer
• Spectroscopy of Blue Stragglers and Turnoff Stars in M67 (NGC 2682)
• Ultra-Lithium-Deficient Halo Stars and Blue Stragglers: A Common Origin?
• Rapid rotation of ultra-Li-depleted halo stars and their association with blue stragglers
• Binary Blue Metal-Poor Stars: Evidence for AGB Mass Transfer
• The Binary Nature of the Subgiant CH Stars
• Galactic orbits of stars with planets
• Stellar Evolution with Enriched Surface Convection Zones I. General Effects of Planet Consumption
• A search for planets in the metal-enriched binary HD 219542

Cited by in corpus (6)

• Origins of Eccentric Extrasolar Planets: Testing the Planet-Planet Scattering Model
• Signatures of rocky planet engulfment in HAT-P-4. Implications for chemical tagging studies
• A giant planet in the triple system HD132563
• Wide Binaries in Tycho-Gaia II: Metallicities, Abundances, and Prospects for Chemical Tagging
• A binary merger origin for inflated hot Jupiter planets
• HIP 10725: The First Solar Twin/Analogue Field Blue Straggler