ULLYSES T TAURI

T Tauri Stars in Galactic Star-Forming Regions

The ULLYSES sample for the T Tauri star survey (listed in the eight tables for different regions) consists of observations with COS/G130M, COS/G160M, STIS/G230L, STIS/G430L, and STIS/G750L. The ULLYSES sample for the T Tauri star monitoring program (listed in the final table) consists of observations with COS/G160M and COS/G230L. The four monitoring stars are observed a total of 24 times each. These observations are split into two epochs, separated by several months. Each epoch consists of four observations per rotation period, over three consecutive rotation periods. The HST UV spectroscopy for the core sample is a mixture of new data collected during HST Cycles 28–29 (2020-2023) and archival data. Community groups are following up with complementary ground- and/or space-based data: photometry covering the time around the HST observations (for the full sample), spectroscopy from X-ray to mid-IR wavelengths, and spectro-polarimetry (for the four temporally monitored stars).

The target tables below include stars that were observed as part of archival-only GO programs. Owing to the variability of T Tauri stars, some observations spanning multiple epochs cannot be coadded. For these targets, ULLYSES coadded products use data from only one epoch. The ULLYSES team creates timeseries products for these targets using vetted successful observations from all epochs.

In all tables, successive columns record:

• a commonly used name for the target that can be resolved by Simbad
• the name that has been adopted by the ULLYSES project and is used in the ULLYSES catalog
• the name that appears in the Phase II files, which can be used for separate queries to MAST. The name used in the ULLYSES products appears in bold face.
• Gaia DR3 coordinates
• the adopted spectral type
• the Johnson V magnitude
• the visual extinction
• the stellar mass
• the accretion rate

Additionally, the monitoring star table includes an entry for the star's rotational period. Simbad target names are hyperlinked to their entry in Simbad, which provides a complete list of aliases, while the ULLYSES target names are hyperlinked to the specific entry in the ULLYSES catalog. References to the source of observational information are also linked.

Four additional columns summarize the HST spectra held by MAST by providing:

• the proposal ID(s) that collected the data. Each ID is linked to its Phase II proposal.
• the instrumental configurations that were used
• the date of the first HST observation of the target
• the current status of the data collection. "In progress" implies that additional visits await scheduling.

Clicking anywhere in a row will also open a table that provides more detailed information about the observations in each visit.

The tables below contain a subset of the information accessible from the ULLYSES search form, which supports querying targets and datasets based on both observational and astrophysical parameters. The "Simbad Resolvable Name" should aid in querying specific targets in the search form. In addition to specialized search parameters, the form also:

• enables direct data file downloads
• allows customized API script to be generated
• provides complete metadata for selected targets to be exported in a variety of file formats

Information for all T Tauri targets can be accessed directly via this predefined query.

Figure 1: Accretion rate as a function of stellar mass for the sample of T Tauri stars observed as part of the ULLYSES program (circles) and taken from archival programs (stars). The sample is color-coded by star-forming region. The new sample observed by the ULLYSES program samples stellar mass and accretion rate relatively uniformly, but with a particular focus on the low mass end (<0.5M_☉), which was previously not extensively observed in the HST archive.

Chamaeleon I Cloud

Corona Australis Association

ε Chamaeleontis Association

η Chamaeleontis Cluster

Lupus Clouds

Orion OB1 Association

σ Orionis Cluster

Taurus-Auriga Association

TW Hydrae Association

Scorpius-Centaurus Association/Lower Centaurus-Crux Subgroup

Scorpius-Centaurus Association/Upper Scorpius Subgroup

Other Stars

Classical T Tauri Star Monitoring Targets