M STARS in the TW HYA ASSOCIATION: STELLAR X-RAYS and DISK DISSIPATION

Costanza Argiroffi, David A. Principe, Joel H. Kastner, Beate Stelzer, Kristina Punzi, Costanza Argiroffi, Uma Gorti, Ilaria Pascucci

Risultato della ricerca: Articlepeer review

16 Citazioni (Scopus)

Abstract

To 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 ∼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 with decreasing T eff for TWA M stars, wherein the earliest-type (M0-M2) stars cluster near and then 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.
Lingua originaleEnglish
pagine (da-a)3-
Numero di pagine11
RivistaTHE ASTRONOMICAL JOURNAL
Volume152
Stato di pubblicazionePublished - 2016

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science

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