TY - JOUR
T1 - A Census of the TW Hya Association with Gaia* * Based on observations made with the Gaia mission, the Two Micron All Sky Survey, the Wide-field Infrared Survey Explorer, Gemini Observatory, and European Southern Observatory telescopes at La Silla and Paranal Observatories.
AU - Luhman, K. L.
N1 - Funding Information:
This work used data from the European Space Agency mission Gaia ( https://www.cosmos.esa.int/gaia ), processed by the Gaia Data Processing and Analysis Consortium (DPAC; https://www.cosmos.esa.int/web/gaia/dpac/consortium ). Funding for the DPAC has been provided by national institutions, in particular the institutions participating in the Gaia Multilateral Agreement. The Gemini data were obtained through programs GS-2014A-Q-44 and GS-2023A-FT-20. Gemini Observatory is a program of NSF's NOIRLab, which is managed by the Association of Universities for Research in Astronomy (AURA) under a cooperative agreement with the National Science Foundation on behalf of the Gemini Observatory partnership: the National Science Foundation (United States), National Research Council (Canada), Agencia Nacional de Investigación y Desarrollo (Chile), Ministerio de Ciencia, Tecnología e Innovación (Argentina), Ministério da Ciência, Tecnologia, Inovações e Comunicações (Brazil), and Korea Astronomy and Space Science Institute (Republic of Korea). 2MASS is a joint project of the University of Massachusetts and IPAC at Caltech, funded by NASA and the NSF. WISE is a joint project of the University of California, Los Angeles, and the JPL/Caltech, funded by NASA. This work used data from the NASA/IPAC Infrared Science Archive, operated by JPL under contract with NASA, and the VizieR catalog access tool and the SIMBAD database, both operated at CDS, Strasbourg, France. The Center for Exoplanets and Habitable Worlds is supported by the Pennsylvania State University, the Eberly College of Science, and the Pennsylvania Space Grant Consortium.
Funding Information:
This work used data from the European Space Agency mission Gaia (https://www.cosmos.esa.int/gaia), processed by the Gaia Data Processing and Analysis Consortium (DPAC; https://www.cosmos.esa.int/web/gaia/dpac/consortium). Funding for the DPAC has been provided by national institutions, in particular the institutions participating in the Gaia Multilateral Agreement. The Gemini data were obtained through programs GS-2014A-Q-44 and GS-2023A-FT-20. Gemini Observatory is a program of NSF's NOIRLab, which is managed by the Association of Universities for Research in Astronomy (AURA) under a cooperative agreement with the National Science Foundation on behalf of the Gemini Observatory partnership: the National Science Foundation (United States), National Research Council (Canada), Agencia Nacional de Investigación y Desarrollo (Chile), Ministerio de Ciencia, Tecnología e Innovación (Argentina), Ministério da Ciência, Tecnologia, Inovações e Comunicações (Brazil), and Korea Astronomy and Space Science Institute (Republic of Korea). 2MASS is a joint project of the University of Massachusetts and IPAC at Caltech, funded by NASA and the NSF. WISE is a joint project of the University of California, Los Angeles, and the JPL/Caltech, funded by NASA. This work used data from the NASA/IPAC Infrared Science Archive, operated by JPL under contract with NASA, and the VizieR catalog access tool and the SIMBAD database, both operated at CDS, Strasbourg, France. The Center for Exoplanets and Habitable Worlds is supported by the Pennsylvania State University, the Eberly College of Science, and the Pennsylvania Space Grant Consortium.
Publisher Copyright:
© 2023. The Author(s). Published by the American Astronomical Society.
PY - 2023/6/1
Y1 - 2023/6/1
N2 - I have used high-precision photometry and astrometry from the third data release of Gaia to perform a survey for members of the TW Hya association (TWA). I have identified candidate members that appear to share similar kinematics and ages with bona fide members compiled by Gagné et al. (2017), and I have assessed their membership using radial velocities and spectroscopic diagnostics of age from various sources. My new catalog of adopted members contains 67 Gaia sources in 55 systems. The histogram of spectral types for TWA peaks near M5 (∼0.15 M ⊙), resembling the distributions measured for other nearby young associations. The UVW velocities of its members indicate that the association is expanding. The rate of expansion corresponds to an age of 9.6 − 0.8 + 0.9 Myr. In a Gaia color-magnitude diagram, the members of TWA exhibit well-defined sequences of single stars and unresolved binary stars. The combined sequence of low-mass stars in TWA is indicative of an age of 11.4 − 1.2 + 1.3 Myr when compared to the sequence for Upper Centaurus Lupus/Lower Centaurus Crux, for which an age of 20 Myr is assumed. Based on these expansion and isochronal ages, I have adopted an age of 10 ± 2 Myr for TWA. Finally, I have used mid-infrared photometry from the Wide-field Infrared Survey Explorer to check for excess emission from circumstellar disks among the TWA members. Fourteen members have detected disks, all of which have been reported in previous studies. The fraction of members at ≤ M6 (≳0.1 M ⊙) that have full, transitional, or evolved disks is 10/52 = 0.19 − 0.06 + 0.08 . That value is similar to the fraction previously measured for the Upper Sco association, which is roughly coeval with TWA.
AB - I have used high-precision photometry and astrometry from the third data release of Gaia to perform a survey for members of the TW Hya association (TWA). I have identified candidate members that appear to share similar kinematics and ages with bona fide members compiled by Gagné et al. (2017), and I have assessed their membership using radial velocities and spectroscopic diagnostics of age from various sources. My new catalog of adopted members contains 67 Gaia sources in 55 systems. The histogram of spectral types for TWA peaks near M5 (∼0.15 M ⊙), resembling the distributions measured for other nearby young associations. The UVW velocities of its members indicate that the association is expanding. The rate of expansion corresponds to an age of 9.6 − 0.8 + 0.9 Myr. In a Gaia color-magnitude diagram, the members of TWA exhibit well-defined sequences of single stars and unresolved binary stars. The combined sequence of low-mass stars in TWA is indicative of an age of 11.4 − 1.2 + 1.3 Myr when compared to the sequence for Upper Centaurus Lupus/Lower Centaurus Crux, for which an age of 20 Myr is assumed. Based on these expansion and isochronal ages, I have adopted an age of 10 ± 2 Myr for TWA. Finally, I have used mid-infrared photometry from the Wide-field Infrared Survey Explorer to check for excess emission from circumstellar disks among the TWA members. Fourteen members have detected disks, all of which have been reported in previous studies. The fraction of members at ≤ M6 (≳0.1 M ⊙) that have full, transitional, or evolved disks is 10/52 = 0.19 − 0.06 + 0.08 . That value is similar to the fraction previously measured for the Upper Sco association, which is roughly coeval with TWA.
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U2 - 10.3847/1538-3881/accf19
DO - 10.3847/1538-3881/accf19
M3 - Article
AN - SCOPUS:85161524820
SN - 0004-6256
VL - 165
JO - Astronomical Journal
JF - Astronomical Journal
IS - 6
M1 - 269
ER -