Journal
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
Volume 486, Issue 2, Pages 1718-1740Publisher
OXFORD UNIV PRESS
DOI: 10.1093/mnras/stz756
Keywords
brown dwarf; stars: formation; stars: low-mass; stars: luminosity function, mass function; stars: pre-main-sequence; open clusters and associations: individual: 25 Orionis
Categories
Funding
- CONACYT/UNAM fellowship
- Posgrado en Astrof isica graduate program at Instituto de Astronomia, UNAM
- programs UNAM-DGAPA-PAPIIT, Mexico [IN116315, IN108117]
- Secretaria de Relaciones Exteriores del Gobierno de Mexico
- Programa de Movilidad e Intercambios Academicos de la Comision Sectorial de Investigacion Cientifica, Universidad de la Republica, Uruguay
- Spanish Ministry of Economy and Competitiveness (MINECO) [AYA2015-68012-C201, AYA2014-58861-C3-1-P, AYA2017-88007-C3-1-P]
- VISTA under ESO program [60. A-9285(B)]
- Argonne National Lab
- University of California Santa Cruz
- University of Cambridge
- Centro de Investigaciones Energeticas, Medioambientales y Tecnologicas-Madrid
- University of Chicago
- University College London
- DES-Brazil consortium
- University of Edinburgh
- ETH-Zurich
- University of Illinois at Urbana-Champaign
- Institut de Ciencies de l'Espai
- Institut de Fisica d'Altes Energies
- Lawrence Berkeley National Lab
- Ludwig-Maximilians Universitat
- University of Michigan
- National Optical Astronomy Observatory
- University of Nottingham
- Ohio State University
- University of Pennsylvania
- University of Portsmouth
- SLAC National Lab
- Stanford University
- University of Sussex
- Texas AM University
- US Department of Energy
- National Science Foundation
- Ministry of Education and Science (Spain)
- Science and Technology Facilities Council (UK)
- Higher Education Funding Council (England)
- National Center for Supercomputing Applications
- Kavli Institute for Cosmological Physics
- Financiadora de Estudos e Projetos (Brazil)
- Fundacao Carlos Chagas Filho de Amparo a Pesquisa (Brazil)
- Conselho Nacional de Desenvolvimento Cientifico e Tecnologico (Brazil)
- Ministerio da Ciencia e Tecnologia (Brazil)
- German Research Foundation
- National Aeronautics and Space Administration
- Alfred P. Sloan Foundation
- Japanese Monbukagakusho
- Max Planck Society
- Higher Education Funding Council for England
- American Museum of Natural History
- Astrophysical Institute Potsdam
- University of Basel
- Case Western Reserve University
- Drexel University
- Fermilab
- Institute for Advanced Study
- Japan Participation Group
- Johns Hopkins University
- Joint Institute for Nuclear Astrophysics
- Kavli Institute for Particle Astrophysics and Cosmology
- Korean Scientist Group
- Chinese Academy of Sciences (LAMOST)
- Los Alamos National Laboratory
- Max-Planck-Institute for Astronomy (MPIA)
- Max-Planck-Institute for Astrophysics (MPA)
- New Mexico State University
- University of Pittsburgh
- Princeton University
- United States Naval Observatory
- University of Washington
Ask authors/readers for more resources
The stellar initial mass function (IMF) is an essential input for many astrophysical studies but only in a few cases has it been determined over the whole cluster mass range, limiting the conclusions about its nature. The 25 Orionis group (25 Ori) is an excellent laboratory for investigating the IMF across the entire mass range of the population, from planetarymass objects to intermediate/high-mass stars. We combine new deep optical photometry with optical and near-infrared data from the literature to select 1687 member candidates covering a 1.1 degrees radius area in 25 Ori. With this sample we derived the 25 Ori system IMF from 0.012 to 13.1 M-circle dot. This system IMF is well described by a two-segment power law with Gamma = -0.74 +/- 0.04 for m < 0.4M(circle dot) and Gamma = 1.50 +/- 0.11 for m >= 0.4 M-circle dot. It is also well described over the whole mass range by a tapered power-law function with Gamma = 1.10 +/- 0.09, m(p) = 0.31 +/- 0.03 and beta = 2.11 +/- 0.09. The best lognormal representation of the system IMF has m(c) = 0.31 +/- 0.04 and sigma = 0.46 +/- 0.05 for m < 1 M-circle dot. This system IMF does not present significant variations with the radii. We compared the resultant system IMF as well as the brown dwarf/star ratio of 0.16 +/- 0.03 that we estimated for 25 Ori with that of other stellar regions with diverse conditions and found no significant discrepancies. These results support the idea that general star-formation mechanisms are probably not strongly dependent on environmental conditions. We found that the substellar and stellar objects in 25 Ori do not have any preferential spatial distributions and confirmed that 25 Ori is a gravitationally unbound stellar association.
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