|Proposal Number||Subject Category||PI Name||Target Name||Total Chandra Time||Title|
|09200905||Stars and WD||Gregory Herczeg||TWA-8,TWA-9||10ks||Evaluating the Role of Photoevaporation in Protoplanetary Disk Dispersal|
|09700908||Active Galaxies and Quasars||John Biretta||M87||35ks||Monitoring the Giant Flare of HST-1 in the M87 Jet|
|09200907||Stars and WD||Lee Hartmann||OB1A-776,OB1A-1192,OB1A-1200,OB1A-1630||40ks||A Hard Look at Stellar Disks at the Epoch of Planet Formation|
Subject Category: Stars and WD
Proposal Number: 09200906
Title: Evaluating the Role of Photoevaporation in Protoplanetary Disk Dispersal
PI Name: Gregory Herczeg
Emission produced by accretion onto the central star leads to photoevaporation, which may play a fundamental role in disk dispersal. Models of disk photoevaporation by the central star are challenged by two potential problems: the emission produced by accretion will be substantially weaker for low-mass stars, and photoevaporation must continue as accretion slows. We propose use HST/ACS SBC PR130L to obtain FUV spectra of WTTSs and of CTTSs at low masses and mass accretion rates to provide crucial data to evaluate photoevaporation models. We will estimate the FUV and EUV luminosities of low-mass CTTSs with small mass accretion rates, CTTSs with transition disks and slowed accretion, and of magnetically-active WTTSs.
Subject Category: Active Galaxies and Quasars
Proposal Number: 09700908
Title: Monitoring the Giant Flare of HST-1 in the M87 Jet
PI Name: John A. Biretta
During 2002, HST and Chandra monitoring of the M87 jet detected a dramatic flare in knot HST-1 located ~1" from the nucleus. Its optical brightness eventually increased seventy-fold and peaked in 2005; the X-rays show a similarly dram atic outburst. In both bands HST-1 is still extremely bright and greatly out-shines the galaxy nucleus. To our knowledge this is the first incidence of an optical or X-ray outburst from a jet region which is spatially distinct from the core source; thi s presents an unprecedented opportunity to study the processes responsible for non-thermal variability and the X-ray emission. We propose six epochs of HST flux monitoring during Cycle 16, as well as seven epochs of Chandra/ACIS observation (5ksec each , six Chandra epochs contemporary with HST).
Subject Category: Stars and WD
Proposal Number: 09200907
Title: A Hard Look at Stellar Disks at the Epoch of Planet Formation
PI Name: Lee Hartmann
We propose to use the HST/ACS/SBC and Chandra/ACIS-S3 to observe the high energy fluxes of 4 stars surrounded by disks in the newly discovered aggregate 25 Ori, the most populous 10 Myr group known within 500 pc. Our observations will cover the 1-25 A and 1250-2000 A bandpasses, and will complement our optical and Spitzer data for these objects, to provide essential i nput to physically-consistent models of disk structure and chemistry in the age range around 10 Myr, thought to be a critical period in the planet-forming process. Our proposed observations will double the number of 10 Myr old accreting stars with know n high energy radiation fields, and will be the first FUV observations of low mass accreting stars in an OB association.