HST Survey of the Orion Nebula Cluster in the H2O 1.4 μm Absorption Band. I. A Census of Substellar and Planetary-mass Objects
Artikel i vetenskaplig tidskrift, 2020

In order to obtain a complete census of the stellar and substellar population, down to a few MJup in the ∼1 Myr old Orion Nebula Cluster, we used the infrared channel of the Wide Field Camera 3 of the Hubble Space Telescope with the F139M and F130N filters. These bandpasses correspond to the 1.4 μm H2O absorption feature and an adjacent line-free continuum region. Out of 4504 detected sources, 3352 (about 75%) appear fainter than m 130 = 14 (Vega mag) in the F130N filter, a brightness corresponding to the hydrogen-burning limit mass (M ≃ 0.072 M⊙) at ∼1 Myr. Of these, however, only 742 sources have a negative F130M-F139N color index, indicative of the presence of H2O vapor in absorption, and can therefore be classified as bona fide M and L dwarfs, with effective temperatures T ≲ 2850 K at an assumed 1 Myr cluster age. On our color-magnitude diagram (CMD), this population of sources with H2O absorption appears clearly distinct from the larger background population of highly reddened stars and galaxies with positive F130M-F139N color index and can be traced down to the sensitivity limit of our survey, m 130 ≃ 21.5, corresponding to a 1 Myr old ≃3 MJup planetary-mass object under about 2 mag of visual extinction. Theoretical models of the BT-Settl family predicting substellar isochrones of 1, 2, and 3 Myr down to ∼1 MJup fail to reproduce the observed H2O color index at M ≲ 20 MJup. We perform a Bayesian analysis to determine extinction, mass, and effective temperature of each substellar member of our sample, together with its membership probability.


Massimo Robberto

Johns Hopkins University

Space Telescope Science Institute (STScI)

Mario Gennaro

Space Telescope Science Institute (STScI)

Maria Giulia Ubeira Gabellini

Universita' degli Studi di Milano

European Southern Observatory (ESO)

Lynne A. Hillenbrand

California Institute of Technology (Caltech)

Camilla Pacifici

Space Telescope Science Institute (STScI)

Leonardo Ubeda

Space Telescope Science Institute (STScI)

Morten Andersen

Gemini Observatory South

Travis Barman

University of Arizona

Andrea Bellini

Space Telescope Science Institute (STScI)

Nicola Da Rio

University of Virginia

Selma E. De Mink

Harvard-Smithsonian Center for Astrophysics

Universiteit Van Amsterdam

Giuseppe Lodato

Universita' degli Studi di Milano

Carlo F. Manara

European Southern Observatory (ESO)

Imants Platais

Johns Hopkins University

Laurent Pueyo

Space Telescope Science Institute (STScI)

Giovanni Maria Strampelli

Johns Hopkins University

Space Telescope Science Institute (STScI)

Universidad de la Laguna

Jonathan Tan

Chalmers, Rymd-, geo- och miljövetenskap, Astronomi och plasmafysik, Galaktisk astrofysik

University of Virginia

L. Testi

European Southern Observatory (ESO)

Astrophysical Journal

0004-637X (ISSN) 1538-4357 (eISSN)

Vol. 896 1 79


Subatomär fysik

Astronomi, astrofysik och kosmologi

Atom- och molekylfysik och optik



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