Tracing High-energy Radiation from T Tauri Stars Using Mid-infrared Neon Emission from Disks
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.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- January 2013
- DOI:
- 10.1088/0004-637X/762/1/62
- arXiv:
- arXiv:1211.2335
- Bibcode:
- 2013ApJ...762...62E
- Keywords:
-
- accretion;
- accretion disks;
- circumstellar matter;
- protoplanetary disks;
- Astrophysics - Solar and Stellar Astrophysics
- E-Print:
- 16 pages, accepted ApJ