|Proposer||(31841) Frederick Walter (firstname.lastname@example.org) obscode: WFM|
|Assigned To||(3663) Dirk Terrell|
|Date Submitted||April 18, 2021|
Southern Low Mass Pre-main Sequence Stars in Orion Simultaneous with HST and TESS
The Hubble Space Telescope (HST) HST ULLYSES project (Ultraviolet Legacy Library of Young Stars as Essential Standards -- https://www.stsci.edu/stsci-research/research-topics-and-programs/ullyses); is designed to obtain a statistically complete catalog of ultraviolet observations of a set of galactic stars while the HST can still obtain UV spectra. Our interest is in a sample of T Tauri stars. This proposal will support a larger program called ODYSSEUS (Outflows and Disks around Young Stars: Synergies for the Exploration of Ullyses Spectra), which includes ground-based optical and near-IR photometry and spectroscopy. The ODYSSEUS campaign is described at https://sites.bu.edu/odysseus/
The first part of this project, targeting 13 stars in the Orion OB1 and sigma Ori star forming regions in November/December 2020, was highly successful. AAVSOnet proposal 159 played an important part in this. One early result was in helping us understand why V505 Ori was undetected by the HST - ground based photometric monitoring showed that the star faded by 2 mag just prior to the HST observation, probably due to obscuration by the accretion disk. This let us successfully replan the observation in February of this year.
Part III of the program is HST snapshots of a sample of southern pre-main sequence stars in the Chamaeleon and Lupus star forming regions. I am requesting time on the AAVSOnet southern telescopes to observe 16 targets brighter than V=17. Eleven of these are currently planned by HST to be observed April 29 though June 6; the other 5 will be planned later, probably for observations during June. The targets are in the TESS field of view either April 28-May 25 or May 26-June 24. Precise HST scheduling will be known 1-2 weeks in advance, and will most likely occur within the plan windows, which are typically 12 hours long.
These targets will be observed with the HST while they are in the TESS field of view. TESS gets broadband (600-1000nm) optical photometry on a 10 minute cadence for typically 27 days. The HST will obtain ultraviolet spectroscopy. The goal of this observing campaign is to supplement the TESS photometry with filter photometry. It is hard to beat the time coverage of the S/N of the TESS data, or the continuous 27 day cadence, but AAVSOnet data can supply the color information which helps distinguish the possible causes of brightenings and fadings in the light curve, which may include magnetic flares, enhanced accretion rates, starspots, and obscuration by a warped dust disk.
The science goals are to understand the disk accretion processes that build up stars and drive their outbursts. The T Tauri stars vary by up to 2 magnitudes. Some are completely irregular; others have characteristic periods of typically 4-10 days, consistent with either the stellar rotation or the inner edge of the accretion disk.
I request sets of BVRI observations on the 4 nights preceding the time of the HST observation, and the night following. If possible, please schedule one of these simultaneously with the HST, but this is generally not possible. This is 5 or 6 observations per target. In addition, I request occasional sets of BVRI observations during the 1-2 month TESS windows in order to "calibrate" the TESS photometry, by seeing how predictably the colors change with brightness.
This program is challenging for all because of the dearth of observing facilities, both amateur and professional, in the south. The ULYSSES program has some photometric time on LCO for this program, but our other professional partners are all located in the north. AAVSOnet data, supplemented by data from southern AAVSO observers, will be instrumental in guaranteeing the success of this program.
Target and dates of observations (if known) are listed below:
|Target||RA (H.HH)||Dec (D.DD)||Magnitude||Telescope||Observation Frequency||Expiration Date||Proprietary Term|
|CHX18N||11.196200||-76.33589||12.5–11.5||BSM_Berry||—||Oct. 23, 2021||No|
There should be 16 targets.
Sz66 has V ~15.5, it is NSV 20359, and lies only 6" to the East of IK Lup (V ~12.5).
It will be an extremely difficult target.
SST J1600-4221 is listed in the proposal at position 16 00 31.05 -42 21 57.5 and with V=15.9.
There is nothing at that position and the SST identifier format does not match the IDs in SIMBAD so we need to know what the star actually is.
There is a 15.9 mag. star 337" away, 2MASS J16000060-4221567. It is classified as YSO in SIMBAD. Other names: SSTc2d J160002.4-422216 = SSTc2d J160002.4-422215. please give more details about this star.
Committed to both Berry and OC61
All targets have been added to VSX with correct positions since these are targets of a T Tauri campaign.
Be sure to point to the correct position in the case of the SSTc2d star:
SSTc2d J160000.6-422158 16 00 00.60 -42 21 56.8 (J2000.0)
I updated the target list information in the proposal text to avoid confusion.
Comments on this proposal are closed.