M STARS IN THE TW HYA ASSOCIATION: STELLAR X-RAYS AND DISK DISSIPATION
AuthorKastner, Joel H.
Principe, David A.
AffiliationUniv Arizona, Lunar & Planetary Lab
planets and satellites: formation
stars: pre-main sequence
MetadataShow full item record
PublisherIOP PUBLISHING LTD
CitationM STARS IN THE TW HYA ASSOCIATION: STELLAR X-RAYS AND DISK DISSIPATION 2016, 152 (1):3 The Astronomical Journal
JournalThe Astronomical Journal
Rights© 2016. The American Astronomical Society. All rights reserved.
Collection InformationThis item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at email@example.com.
AbstractTo investigate the potential connection between the intense X-ray emission from young low-mass stars and the lifetimes of their circumstellar planet-forming disks, we have compiled the X-ray luminosities (L-X) of M stars in the similar to 8 Myr old TW Hya Association (TWA) for which X-ray data are presently available. Our investigation includes analysis of archival Chandra data for the TWA binary systems TWA 8, 9, and 13. Although our study suffers from poor statistics for stars later than M3, we find a trend of decreasing L-X/L-bol with decreasing T-eff for TWA M stars, wherein the earliest-type (M0-M2) stars cluster near log(L-X/L-bol) approximate to -3.0 and then log(L-X/L-bol) decreases, and its distribution broadens, for types M4 and later. The fraction of TWA stars that display evidence for residual primordial disk material also sharply increases in this same (mid-M) spectral type regime. This apparent anticorrelation between the relative X-ray luminosities of low-mass TWA stars and the longevities of their circumstellar disks suggests that primordial disks orbiting early-type M stars in the TWA have dispersed rapidly as a consequence of their persistent large X-ray fluxes. Conversely, the disks orbiting the very lowest-mass pre-MS stars and pre-MS brown dwarfs in the Association may have survived because their X-ray luminosities and, hence, disk photoevaporation rates are very low to begin with, and then further decline relatively early in their pre-MS evolution.
VersionFinal published version
SponsorsNASA Astrophysics Data Analysis Program [NNX12AH37G]; NASA Exoplanets program [NNX16AB43G]; National Science Foundation [AST-1108950]; CONICYT-FONDECYT ; Millennium Science Initiative (Chilean Ministry of Economy) [RC 130007]