Astron. Astrophys. 345, 181-186 (1999)

1. Introduction

Circumstellar disks surrounding young stars are remnants of the star formation process. The collapse of a molecular cloud leads to the formation of disks with accretion onto a central stellar-like object. These circumstellar disks are thought to disappear on a timescale of several million years (Backman & Paresce 1993). Nevertheless, faint disks surround several main-sequence stars, such as Vega and Pictoris (Aumann et al. 1984; Gillett 1986), suggesting the presence of a reservoir of bodies, the collisions of which replenish the disk. It is generally assumed that planets may form in these dusty disks (e.g. Beckwith & Sargent 1996). Therefore, it is interesting to study the evolution of these circumstellar dusty disks, which can be observed in the infrared, due to the thermal radiation of the circumstellar dust.

HD 142527 (F7IIIe) is a so-called 'isolated' Herbig Ae/Be star (or Fe star in this particular case): its strong infrared excess and H emission argue for a young age, but it is not located in a well known star-forming region. From the Digitized Sky Survey (consulted at http://skys.gsfc.nasa.gov/cgi-bin/skyview_advanced.pl), it can be seen that HD 142527 has a small weak nebulous environment, in which no other but this IRAS-object is present. Thus, it might be a transition object between the youngest, embedded stars and main-sequence objects such as Beta Pic. However, this picture is not confirmed by Hipparcos parallax-measurements of this star, which, confronted to stellar-evolution models, suggest an age 10⁵ yr (van den Ancker et al. 1998), which is less than the age of several embedded objects.

HD 142527 is an ideal target for infrared spectroscopy, since its circumstellar dust is bright, and since its isolated nature avoids confusion with the loose surroundings that occur for more embedded sources.

© European Southern Observatory (ESO) 1999

Online publication: April 12, 1999
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