Outbursts on normal stars. FH Leo misclassified as a novalike variable

Abstract

We present high resolution spectroscopy of the common proper motion system FH Leo (components HD 96273 and BD+07 2411B), which has been classified as a novalike variable due to an outburst observed by Hipparcos, and we present and review the available photometry. We show from our spectra that neither star can possibly be a cataclysmic variable, instead they are perfectly normal late-F and early-G stars. We measured their radial velocities and derived the atmospheric fundamental parameters, abundances of several elements including Fe, Ni, Cr, Co, V, Sc, Ti, Ca and Mg, and we derive the age of the system. From our analysis we conclude that the stars do indeed constitute a physical binary. However, the observed outburst cannot be readily explained. We examine several explanations, including pollution with scattered light from Jupiter, binarity, microlensing, background supernovae, interaction with unseen companions and planetary engulfment. While no explanation is fully satisfactory, the scattered light and star-planet interaction scenarios emerge as the least unlikely ones, and we give suggestions for further study.

arXiv comment8 pages, 7 figures. Accepted for publication in A&A

References in corpus (18)

• Evolutionary tracks and isochrones for low- and intermediate-mass stars: from 0.15 to 7 M_sun, and from Z=0.0004 to 0.03
• Spectroscopic [Fe/H] for 98 extra-solar planet-host stars: Exploring the probability of planet formation
• A Catalog and Atlas of Cataclysmic Variables - The Living Edition
• The accretion of planets and brown dwarfs by giant stars -- II. solar mass stars on the red giant branch
• Isochrone ages for field dwarfs: method and application to the age-metallicity relation
• HD 80606 b, a planet on an extremely elongated orbit
• Are superflares on solar analogues caused by extra-solar planets?
• A Critical Examination of Li Pollution and Giant Planet Consumption by a Host Star
• High precision effective temperatures for 181 F--K dwarfs from line-depth ratios
• A model of an expanding giant that swallowed planets for the eruption of V838 Monocerotis
• New measurement of the Lithium-6/Lithium-7 isotopic ratio in the extra-solar planet host star HD82943 and line blending in the Li 6708 A region
• Abundance analysis of targets for the COROT / MONS asteroseismology missions II. Abundance analysis of the COROT main targets
• The CORALIE survey for southern extra-solar planets XI. The return of the giant planet orbiting HD192263
• Membership, metallicity and lithium abundances for solar-type stars in NGC 6633
• Abundance analysis of targets for the COROT / MONS asteroseimology missions I. Semi-automatic abundance analysis of the gamma Dor star HD 49434
• WIYN/Hydra Detection of Lithium Depletion in F Stars of the Young Open Cluster M35 and Implications for the Development of the Lithium Gap
• The photospheric abundances of active binaries II. Atmospheric parameters and abundance patterns for 6 single-lined RS CVn systems
• Lithium Abundances in Wide Binaries with Solar-Type Twin Components

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