2009AJ....137.3210C -
Astron. J., 137, 3210-3221 (2009/February-0)
The X-ray environment during the epoch of terrestrial planet formation: Chandra observations of h Persei.
CURRIE T., EVANS N.R., SPITZBART B.D., IRWIN J., WOLK S.J., HERNANDEZ J., KENYON S.J. and PASACHOFF J.M.
Abstract (from CDS):
We describe Chandra/ACIS-I observations of the massive ∼ 13-14 Myr-old cluster, h Persei, part of the famous Double Cluster (h and χ Persei) in Perseus. Combining the list of Chandra-detected sources with new optical/IR photometry and optical spectroscopy reveals ∼ 165 X-ray bright stars with V ≲ 23. Roughly 142 have optical magnitudes and colors consistent with cluster membership. The observed distribution of Lx peaks at Lx∼ 1030.3 erg/s and likely traces the bright edge of a far larger population of ~ 0.4-2 M☉X-ray active stars. From a short list of X-ray active stars with IRAC 8 µm excess from warm, terrestrial zone dust, we derive a maximum X-ray flux incident on forming terrestrial planets. Although there is no correlation between X-ray activity and IRAC excess, the fractional X-ray luminosity correlates with optical colors and spectral type. By comparing the distribution of Lx/L{sstarf} versus spectral type and V - I in h Per with results for other 1-100 Myr-old clusters, we show that stars slightly more massive than the Sun (≳ 1.5 M☉) fall out of X-ray saturation by ~ 10-15 Myr. Changes in stellar structure for ≳ 1.5 M☉ stars likely play an important role in this decline of X-ray emission.
Abstract Copyright:
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Journal keyword(s):
open clusters and associations: individual: NGC 869 - planetary systems: formation - stars: pre-main sequence - X-rays: stars
VizieR on-line data:
<Available at CDS (J/AJ/137/3210): table1.dat table2.dat>
Nomenclature:
Tables 1-2: [CES2009] NNN N=165 among (Nos 1-330).
Simbad objects:
176
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