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Title: A PAN-STARRS + UKIDSS SEARCH FOR YOUNG, WIDE PLANETARY-MASS COMPANIONS IN UPPER SCORPIUS

We have combined optical and NIR photometry from Pan-STARRS 1 and UKIDSS to search the young (5-10 Myr) star-forming region of Upper Scorpius for wide ( Almost-Equal-To 400-4000 AU) substellar companions down to {approx}5 M{sub Jup}. Our search is Almost-Equal-To 4 mag deeper than previous work based on the Two Micron All Sky Survey. We identified several candidates around known stellar members using a combination of color selection and spectral energy distribution fitting. Our follow-up spectroscopy has identified two new companions as well as confirmed two companions previously identified from photometry, with spectral types of M7.5-M9 and masses of {approx}15-60 M{sub Jup}, indicating a frequency for such wide substellar companions of {approx}0.6% {+-} 0.3%. Both USco 1610-1913B and USco 1612-1800B are more luminous than expected for their spectral type compared with known members of Upper Sco. HIP 77900B has an extreme mass ratio (M{sub 2}/M{sub 1} Almost-Equal-To 0.005) and an extreme separation of 3200 AU. USco 1602-2401B also has a very large separation of 1000 AU. We have also confirmed a low-mass stellar companion, USco 1610-2502B (730 AU, M5.5). Our substellar companions appear both non-coeval with their primary stars according to evolutionary models and, as a group, are systematically moremore » luminous than the Upper Sco cluster sequence. One possible reason for these luminosity discrepancies could be different formation processes or accretion histories for these objects.« less
Authors:
; ; ; ; ; ; ;  [1] ;  [2]
  1. Institute of Astronomy, University of Hawaii, 2680 Woodlawn Drive, Honolulu, HI 96822 (United States)
  2. Department of Astrophysical Sciences, Princeton University, Princeton, NJ 08544 (United States)
Publication Date:
OSTI Identifier:
22131063
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 773; Journal Issue: 1; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; COLOR; ENERGY SPECTRA; LUMINOSITY; MASS; NEAR INFRARED RADIATION; PHOTOMETRY; SKY; SPECTROSCOPY; STARS