Why Protoplanetary Systems with this viewing geometry are important:
- Age Estimates for UXORs
- These stars have the same viewing geometry as the beta Pic system.
- Evolutionary age estimates (van den Ancker et al. 1997;
Natta et al. 1998) suggest that the intermediate-mass UXORs are
in the 1-4 Myr age range. Some solar-mass UXORs may be 10 Myr or
older.
- These age estimates are compatible with the time required to produce
Jupiter-mass planets (Pollack et al. 1996), thus these systems may
be in the earliest, observable phase of planet formation.
- Same Viewing Geometry as Beta Pic
- use these systems to test models for planetary system formation
and for clearing of the dust disk.
- can probe evolution of small dust grain population through
line of sight extinction studies
- The edge-on geometry is the preferred observation geometry for
coronagraphic and mid-IR imaging of disk systems (Kalas and
Jewitt 1996)
- This is the geometry of All systems with detection of beta Pic-like
infalling material. The figure shows
transient red absorption components of the NaID lines in UX Ori . The These features have been interpreted as the
gaseous comae
and tails of swarms of star-grazing planetesimals (Beust et al. 1996).
Annimated Gifs showing a transient infall event in the 4 Myr
old AB Aur system. This star exhibited UXOR variability in the 1920s.
- Long-term (multi-year) fluctuations in the frequency of optical
minima are known for a number of these objects. Schevchenko et al.
(1993) have reported apparent periodicities for several stars. If
confirmed, any periodic activity may indicate the presence of large
bodies (e.g. Jupiter-mass planets, brown dwarf stars) within the
disk.
This document is part of the EXPORT Team Web Site
Updated:Tuesday April 28, 1998.
