1,093 research outputs found
Probing the Low Mass Stellar End of the eta Chamaeleontis Cluster
We have identified three faint new members of the eta Chamaeleontis cluster.
Spectral types of the new members are estimated to be ~M5 based on their TiO
band strengths and broadband colors. With an age of 5-8 Myr for the cluster,
masses of these new members are estimated to be ~0.08 Msun. All three display
strong Li 6708A absorption and Halpha emission features including one with
Halpha emission equivalent width ~60A along with HeI 6678 & 7605 A emission
features that are characteristics of classical T Tauri stars.Comment: 11 pages, 4 figures, 2 tables, accepted in Ap
Dusty Debris Disks as Signposts of Planets: Implications for SIRTF
Submillimeter and near-infrared images of cool dusty debris disks and rings
suggest the existence of unseen planets. At dusty but non-imaged stars,
semi-major axes of associated planets can be estimated from the dust
temperature. For some young stars these semi-major axes are greater than an arc
second as seen from Earth. Such stars are excellent targets for sensitive
near-infrared imaging searches for warm planets. To probe the full extent of
the dust and hence of potential planetary orbits, SIRTF observations should
include measurements with the 160mu filter.Comment: 8 figures, 1 table, accepted in Ap
New Members of the Scorpius Centaurus Complex and Ages of its sub-regions
We have spectroscopically identified about 100 G-, K- and M-type members of
the Scorpius Centaurus complex. To deduce the age of these young stars we
compare their Li 6708 absorption line strengths against those of stars
in the TW Hydrae association and Pictoris moving group. These line
strengths indicate that Sco-Cen stars are younger than Pic stars whose
ages of ~12 Myr have previously been derived from a kinematic traceback
analysis. Our derived age,~10Myr, for stars in the LCC and UCL subgroups of
ScoCen is younger than previously published ages based on the moving cluster
method and upper main sequence fitting. The discrepant ages are likely due to
an incorrect (or lack of) cross-calibration between model-dependent and
model-independent age-dating methods.Comment: 3 figures, accepted in A
- …