RW Aur A : SpeX Spectral Evidence for Differentiated Planetesimal Formation, Migration and Destruction in an 3 Myr Old Excited CTTS System

• Main Authors: Lisse, C. M, Sitko, M. L, Wolk, S. J, Günther, H. M, Brittain, S, Green, J. D, Steckloff, J, Johnson, B, Espaillat, C. C, Koutoukali, M, Moorman, S. Y, Jackson, A. P
• Format: Journal Article
• Language: English
• Published: 06-03-2022
• Subjects: Physics - Earth and Planetary Astrophysics; Physics - Solar and Stellar Astrophysics
• DOI: 10.48550/arxiv.2201.10465

We present 2007 - 2020 SpeX VISNIR spectral monitoring of the highly variable
RW Aur A CTTS. We find direct evidence for a highly excited, IR bright,
asymmetric, and time variable system. Comparison of the spectral and temporal
trends found determines 5 different components: (1) a stable continuum from 0.7
- 1.3 um, with approx color temperature 4000K, produced by the CTTS
photospheric surface; (2) variable hydrogen emission lines emitted from hot
excited hydrogen in the CTTSs protostellar atmosphere/accretion envelope; (3)
hot CO gas in the CTTSs protostellar atmosphere/accretion envelope; (4) highly
variable 1.8-5.0 um thermal continuum emission with color temperature ranging
from 1130 to 1650K, due to a surrounding accretion disk that is spatially
variable and has an inner wall at r = 0.04 AU and T = 1650K, and outer edges at
approx 1200K; and (5) transient, bifurcated signatures of abundant Fe II +
associated SI, SiI, and SrI in the systems jet structures. The bifuracted
signatures first appeared in 2015, but these collapsed and disappeared into a
small single peak protostellar atmosphere feature by late 2020. The temporal
evolution of RW Aur As spectral signatures is consistent with a dynamically
excited CTTS system forming differentiated Vesta-sized planetesimals in an
asymmetric accretion disk and migrating them inward to be destructively
accreted. By contrast, nearby, coeval binary companion RW Aur B evinces only
(1) a stable WTTS photospheric continuum from 0.7 - 1.3 um + (3) cold CO gas in
absorption + (4) stable 1.8-5.0 um thermal disk continuum emission with color
temperature approx 1650K.