|Proposer||(31841) Frederick Walter (email@example.com) obscode: WFM|
|Assigned To||(3663) Dirk Terrell|
|Date Submitted||Oct. 22, 2020|
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 first part of this project involves obtaining UV spectra of 13 stars in the Orion OB1 and sigma Ori star forming regions in November/December 2020.
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.
The 13 low mass PMS stars in Orion will be observed with TESS 11/19 - 12/17/2020, and with the HST for a few hours during that window. The targets are listed,
Target RA (J2000) Dec mean V orbits dates (2020)
A: Simultaneity with the HST data will give the colors of the targets while the UV spectra are being obtained. In the most fortuitous case, a target will be scheduled during 4 consecutive orbits observable from the ground at night. In this case, we ask for a minimum of one set of BVRI observations during one of the ~50 minute long observations, and a maximum of one set of BVRI observations during each 96 minutes HST orbit, if possible.
B: These observations will be used to establish color trends, especially if the HST observation occurs during local day.
C: The purpose of these observations is to obtain a color calibration of TESS. Basically, by hitting these stars at random times, plus the times in parts A and B, we sample random brightnesses. We want to know if the star is bluer or redder when bright.
These observation should be scheduled on the SRO, NMSU, or MJUO telescopes.
AAVSOnet observations will complement these other data and assist our goal of achieving dense photometric coverage on this large number of targets.
|Target||RA (H.HH)||Dec (D.DD)||Magnitude||Telescope||Observation Frequency||Expiration Date||Proprietary Term|
|TX Ori||5.642692||-2.73725||12.6–11.6||SRO||—||May 9, 2021||No|
|CVSO-165||5.650714||-1.34231||14.2–13.2||SRO||—||May 9, 2021||No|
|CVSO-109||5.542406||-1.22947||14.5–13.5||SRO||—||May 9, 2021||No|
|CVSO-146||5.596114||-2.75269||14.5–13.5||SRO||—||May 9, 2021||No|
|V505 Ori||5.640906||-2.75269||14.7–13.7||SRO||—||May 9, 2021||No|
|CVSO-104||5.535136||-1.18356||14.7–13.7||SRO||—||May 9, 2021||No|
|V510 Ori||5.661064||-2.52275||14.8–13.8||SRO||—||May 9, 2021||No|
|CVSO-90||5.522397||-0.82217||15.1–14.1||SRO||—||May 9, 2021||No|
|CVSO-107||5.540497||-0.61483||15.3–14.3||SRO||—||May 9, 2021||No|
|CVSO-58||5.489794||-1.42097||15.4–14.4||SRO||—||May 9, 2021||No|
|CVSO-176||5.673375||-0.52258||16.1–15.1||SRO||—||May 9, 2021||No|
|CVSO-36||5.430658||1.82703||16.6–15.6||SRO||—||May 9, 2021||No|
|CVSO-17||5.384644||1.62092||16.7–15.7||SRO||—||May 9, 2021||No|
Comments from Arne:
Technically, there shouldn't be a problem, except that Orion is full of variable stars, and finding suitable comparison stars might be a challenge. The fainter star fields should be examined closely for nearby companions, especially since precision photometry is needed. In addition, the scheduling and setup will be complex. I'd suggest getting test exposures of each target, so that you can adjust exposure times and have the plans ready to go.
It is required that the proposer provide a csv or xlsx file with Target names, RA, Dec, mag min, mag max. This will allow easy import into the plan. RA; Dec should be J2000, sexagesimal.
Email sent to proposer 10/30/2020
Committed to NH and NM.
Committed to SRO and OC61.
Comments on this proposal are closed.