Tracing High-energy Radiation from T Tauri Stars Using Mid-infrared Neon Emission from Disks

January 2013 • 2013ApJ...762...62E

Authors • Espaillat, C. • Ingleby, L. • Furlan, E. • McClure, M. • Spatzier, A. • Nieusma, J. • Calvet, N. • Bergin, E. • Hartmann, L. • Miller, J. M. • Muzerolle, J.

Abstract • High-energy radiation from T Tauri stars (TTS) influences the amount and longevity of gas in disks, thereby playing a crucial role in the creation of gas giant planets. Here we probe the high-energy ionizing radiation from TTS using high-resolution mid-infrared (MIR) Spitzer Infrared Spectrograph neon forbidden line detections in a sample of disks from IC 348, NGC 2068, and Chamaeleon. We report three new detections of [Ne III] from CS Cha, SZ Cha, and T 54, doubling the known number of [Ne III] detections from TTS. Using [Ne III]-to-[Ne II] ratios in conjunction with X-ray emission measurements, we probe high-energy radiation from TTS. The majority of previously inferred [Ne III]/[Ne II] ratios based on [Ne III] line upper limits are significantly less than 1, pointing to the dominance of either X-ray radiation or soft extreme-ultraviolet (EUV) radiation in producing these lines. Here we report the first observational evidence for hard EUV-dominated Ne forbidden line production in a T Tauri disk: [Ne III]/[Ne II] ~ 1 in SZ Cha. Our results provide a unique insight into the EUV emission from TTS, by suggesting that EUV radiation may dominate the creation of Ne forbidden lines, albeit in a minority of cases.

Links

• SIMBAD http://simbad.u-strasbg.fr/simbo.pl?bibcode=2013ApJ...762...62E
• PDF https://iopscience.iop.org/article/10.1088/0004-637X/762/1/62/pdf
• PREPRINT http://arxiv.org/abs/1211.2335
• DATA https://cda.harvard.edu/chaser?obsid=8584,8585,10763
• DATA https://irsa.ipac.caltech.edu/bibdata/2013/E/2013ApJ...762...62E.html
• ELECTR https://doi.org/10.1088/0004-637X/762/1/62
• SPIRES http://inspirehep.net/search?p=find+eprint+arXiv:1211.2335