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Issue A&A Volume 419, Number 1, May III 2004 Page(s) 301 - 318 Section Stellar structure and evolution DOI 10.1051/0004-6361:20034561

A&A 419, 301-318 (2004)
DOI: 10.1051/0004-6361:20034561

Study of the properties and spectral energy distributions of the Herbig AeBe stars HD 34282 and HD 141569

B. Merín¹, B. Montesinos^{1, 2}, C. Eiroa³, E. Solano¹, A. Mora³, P. D'Alessio⁴, N. Calvet⁵, R. D. Oudmaijer⁶, D. de Winter⁷, J. K. Davies⁸, A. W. Harris⁹, A. Cameron¹⁰, H. J. Deeg¹¹, R. Ferlet¹², F. Garzón¹¹, C. A. Grady¹³, K. Horne¹⁰, L. F. Miranda², J. Palacios³, A. Penny¹⁴, A. Quirrenbach¹⁵, H. Rauer⁹, J. Schneider¹⁶ and P. R. Wesselius<sup>17

1</sup>  Laboratorio de Astrofísica Espacial y Física Fundamental (LAEFF), Apartado 50727, 28080 Madrid, Spain
²  Instituto de Astrofísica de Andalucía-CSIC, Apartado 3004, 18080 Granada, Spain
³  Departamento de Física Teórica, Módulo C-XI, Facultad de Ciencias, Universidad Autónoma de Madrid, 28049 Cantoblanco, Madrid, Spain
⁴  Centro de Radioastronomía y Astrofísica (UNAM), Apartado Postal 3-72 (Xangari), 58089 Morelia, Mexico
⁵  Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138, USA
⁶  Department of Physics and Astronomy, University of Leeds, Leeds LS2 9JT, UK
⁷  TNO/TPD-Space Instrumentation, Stieltjesweg 1, PO Box 155, 2600 AD Delft, The Netherlands
⁸  Astronomy Technology Centre, Royal Observatory, Blackford Hill, Edinburgh EH9 3HJ, UK
⁹  DLR Department of Planetary Exploration, Rutherfordstrasse 2, 12489 Berlin, Germany
¹⁰  Department of Physics and Astronomy, University of St. Andrews, North Haugh, St. Andrews KY16 9SS, Scotland, UK
¹¹  Instituto de Astrofísica de Canarias, c/Via Láctea s/n, 38200 La Laguna, Tenerife, Spain
¹²  CNRS, Institute d'Astrophysique de Paris, 98bis Bd. Arago, 75014 Paris, France
¹³  NOAO/STIS, Goddard Space Flight Center, Code 681, NASA/GSFC, Greenbelt, MD 20771, USA
¹⁴  Rutherford Appleton Laboratory, Chilton, Didcot, Oxfordshire OX11 0QX, UK
¹⁵  Sterrewacht Leiden, PO Box 9513, 2300 RA Leiden, The Netherlands
¹⁶  Observatoire de Paris, Place Jules Janssen, 92195 Meudon, France
¹⁷  SRON, Universiteitscomplex "Zernike", Landleven 12, PO Box 800, 9700 AV Groningen, The Netherlands

(Received 22 October 2003 / Accepted 10 February 2004 )

Abstract
We present a study of the stellar parameters, distances and spectral energy distributions (SEDs) of HD 34282 and HD 141569 , two pre-main sequence Herbig AeBe stars. Both objects have been reported to show "anomalous positions" in the HR diagram in the sense that they appear below the main sequence. A significant result of this work is that both stars are metal-deficient. The Hipparcos distance of HD 34282 is very uncertain and the current study places the star at the expected evolutionary position in the HR diagram, i.e. as a PMS star. The distance for HD 141569 found in this work matches the Hipparcos distance, and the problem of its anomalous position is solved as a result of the low metallicity of the object: using the right metallicity tracks, the star is in the PMS region. The SEDs are constructed using data covering ultraviolet to millimetre wavelengths. Physical, non-parametric models, have been applied in order to extract some properties of the disks surrounding the stars. The disk around HD 34282 is accreting actively, it is massive and presents large grains in the mid-plane and small grains in the surface. HD 141569 has a very low mass disk, which is in an intermediate stage towards a debris-type disk.

Key words: stars: pre-main sequence -- stars: fundamental parameters -- stars: planetary systems: protoplanetary disks

Offprint request: B. Merín, bruno@laeff.esa.es

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