HD 85567: A Herbig B[e] star or an interacting B[e] binary

Abstract

Context. HD 85567 is an enigmatic object exhibiting the B[e] phenomenon, i.e. an infrared excess and forbidden emission lines in the optical. The object's evolutionary status is uncertain and there are conflicting claims that it is either a young stellar object or an evolved, interacting binary. Aims. To elucidate the reason for the B[e] behaviour of HD 85567, we have observed it with the VLTI and AMBER. Methods. Our observations were conducted in the K-band with moderate spectral resolution (R~1500, i.e. 200 km/s). The spectrum of HD 85567 exhibits Br gamma and CO overtone bandhead emission. The interferometric data obtained consist of spectrally dispersed visibilities, closure phases and differential phases across these spectral features and the K-band continuum. Results. The closure phase observations do not reveal evidence of asymmetry. The apparent size of HD 85567 in the K-band was determined by fitting the visibilities with a ring model. The best fitting radius, 0.8 +/- 0.3 AU, is relatively small making HD 85567 undersized in comparison to the size-luminosity relationship based on YSOs of low and intermediate luminosity. This has previously been found to be the case for luminous YSOs, and it has been proposed that this is due to the presence of an optically thick gaseous disc. We demonstrate that the differential phase observations over the CO bandhead emission are indeed consistent with the presence of a compact (~1 AU) gaseous disc interior to the dust sublimation radius. Conclusions. The observations reveal no sign of binarity. However, the data do indicate the presence of a gaseous disc interior to the dust sublimation radius. We conclude that the data are consistent with the hypothesis that HD 85567 is a YSO with an optically thick gaseous disc within a larger dust disc that is being photo-evaporated from the outer edge.

Accepted for publication in A & A

References in corpus (11)

• VOSA: Virtual Observatory SED Analyzer. An application to the Collinder 69 open cluster
• Interferometric data reduction with AMBER/VLTI.Principle,estimators and illustration
• The origin of hydrogen line emission for five Herbig Ae/Be stars spatially resolved by VLTI/AMBER spectro-interferometry
• Few Skewed Disks Found in First Closure-Phase Survey of Herbig Ae/Be stars
• Circumstellar disks around Herbig Be stars
• Detection of an inner gaseous component in a Herbig Be star accretion disk: Near- and mid-infrared spectro-interferometry and radiative transfer modeling of MWC 147
• Strong Near-Infrared Emission Interior to the Dust-Sublimation Radius of Young Stellar Objects MWC275 and AB Aur
• Spectrally Dispersed K-Band Interferometric Observations of Herbig Ae/Be Sources: Inner Disk Temperature Profiles
• Relation between the luminosity of young stellar objects and their circumstellar environment
• Constraining the wind launching region in Herbig Ae stars: AMBER/VLTI spectroscopy of HD104237
• AMBER and CRIRES observations of the binary sgB[e] star HD 327083: evidence of a gaseous disc traced by CO bandhead emission

Cited by in corpus (12)

• Accretion disks in luminous young stellar objects
• ISPY -- NACO Imaging Survey for Planets around Young stars: Survey description and results from the first 2.5 years of observations
• Dusty Blue Supergiants: News from High-Angular Resolution Observations
• Tracing Accretion onto Herbig Ae/Be Stars Using the Brγ Line
• A disk asymmetry in motion around the B[e] star MWC158
• A resolved, au-scale gas disk around the B[e] star HD 50138
• Towards Understanding The B[e] Phenomenon: VI. Nature and Spectral Variations of HD 85567
• Evolutionary status of isolated B[e] stars
• Herschel observations of dust around the high-mass X-ray binary GX 301-2
• Study of the sub-AU disk of the Herbig B[e] star HD 85567 with near-infrared interferometry
• Disentangling the two sub-populations of early Herbig Be stars using VLT/X-Shooter spectra
• BCD spectrophotometry for massive stars in transition phases