Spectral Evidence for an Inner Carbon-Rich Circumstellar Dust Belt in the Young HD36546 A-Star System
Carey M. Lisse, Mike L. Sitko, Ray W. Russell, Massimo Marengo, Thayne Currie, Carl Melis, Tushar Mittal, Inseok Song
(Submitted on 20 Apr 2017)
Using the NASA/IRTF SpeX & BASS spectrometers we have obtained novel 0.7 – 13 um observations of the newly imaged HD36546 debris disk system. The SpeX spectrum is most consistent with the photospheric emission expected from an Lstar ~ 20 Lsun, solar abundance A1.5V star with little/no extinction and excess emission from circumstellar dust detectable beyond 4.5 um. Non-detections of CO emission lines and accretion signatures point to the gas poor circumstellar environment of a very old transition disk. Combining the SpeX and BASS spectra with archival WISE/AKARI/IRAS/Herschel photometery, we find an outer cold dust belt at ~135K and 20 – 40 AU from the primary, likely coincident with the disk imaged by Subaru (Currie et al. 2017), and a new second inner belt with temperature ~570K and an unusual, broad SED maximum in the 6 – 9 um region, tracing dust at 1.1 – 2.2 AU. An SED maximum at 6 – 9 um has been reported in just two other A-star systems, HD131488 and HD121191, both of ~10 Myr age (Melis et al. 2013). From Spitzer, we have also identified the ~12 Myr old A7V HD148567 system as having similar 5 – 35 um excess spectral features (Mittal et al. 2015). The Spitzer data allows us to rule out water emission and rule in carbonaceous materials – organics, carbonates, SiC – as the source of the 6 – 9 um excess. Assuming a common origin for the 4 young Astar systems’ disks, we suggest they are experiencing an early era of carbon-rich planetesimal processing.
Comments: 14 Pages, 2 Figures
Subjects: Solar and Stellar Astrophysics (astro-ph.SR); Earth and Planetary Astrophysics (astro-ph.EP)
Cite as: arXiv:1704.06348 [astro-ph.SR] (or arXiv:1704.06348v1 [astro-ph.SR] for this version)
Submission history
From: Carey Lisse
[v1] Thu, 20 Apr 2017 21:42:27 GMT (1822kb)
http://xxx.lanl.gov/abs/1704.06348
