Evolution of dust and ice features around FU Orionis objects

Details Evolution of dust and ice features around FU Orionis objects Evolution of dust and ice features around FU Orionis objects

2007-06-25

arxiv.org/abs/0706.3593v1

Astronomy and Astrophysics

Astrophysics

accepted for publication in ApJ; 63 pages preprint style including 8 tables and 24 figures

Scientific paper

10.1086/521219

(abridged) We present spectroscopy data for a sample of 14 FUors and 2 TTauri stars observed with the Spitzer Space Telescope or with the Infrared Space Observatory (ISO). Based on the appearance of the 10 micron silicate feature we define 2 categories of FUors. Objects showing the silicate feature in absorption (Category 1) are still embedded in a dusty and icy envelope. The shape of the 10 micron silicate absorption bands is compared to typical dust compositions of the interstellar medium and found to be in general agreement. Only one object (RNO 1B) appears to be too rich in amorphous pyroxene dust, but a superposed emission feature can explain the observed shape. We derive optical depths and extinction values from the silicate band and additional ice bands at 6.0, 6.8 and 15.2 micron. In particular the analysis of the CO_2 ice band at 15.2 micron allows us to search for evidence for ice processing and constrains whether the absorbing material is physically linked to the central object or in the foreground. For objects showing the silicate feature in emission (Category 2), we argue that the emission comes from the surface layer of accretion disks. Analyzing the dust composition reveals that significant grain growth has already taken place within the accretion disks, but no clear indications for crystallization are present. We discuss how these observational results can be explained in the picture of a young, and highly active accretion disk. Finally, a framework is proposed as to how the two categories of FUors can be understood in a general paradigm of the evolution of young, low-mass stars. Only one object (Parsamian 21) shows PAH emission features. Their shapes, however, are often seen toward evolved stars and we question the object's status as a FUor and discuss other possible classifications.

Affiliated with

Also associated with

No associations

Rating

Evolution of dust and ice features around FU Orionis objects does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.

If you have personal experience with Evolution of dust and ice features around FU Orionis objects, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Evolution of dust and ice features around FU Orionis objects will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-230010