New members in the Upper Sco association from the UKIDSS Early Data Release

Abstract

We present the results of a 9.3 square degree infrared (ZYJHK) survey in the Upper Scorpius association extracted from the UKIRT Infrared Deep Sky Survey (UKIDSS) Galactic Cluster Survey Early Data Release. We have selected a total of 112 candidates from the ($Z-J$,$Z$) colour-magnitude diagram over the Z=12.5-20.5 magnitude range, corresponding to M = 0.25-0.01 Msun at an age of 5 Myr and a distance of 145 pc. Additional photometry in J and K filters revealed most of them as reddened stars, leaving 32 possible members. Among them, 15 have proper motion consistent with higher mass members from Hipparcos and optical spectra with strong Halpha in emission and weak gravity features. We have also extracted two lower mass candidate members for which no optical spectra are in hand. Three members exhibit strong Halpha equivalent widths (>20 Angstroms), suggesting that they could still undergo accretion whereas two other dwarfs show signs of chromospheric activity. The likelihood of the binarity of a couple of new stellar and substellar members is discussed as well.

12 pages, 6 figures, 5 tables, accepted to MNRAS

References in corpus (1)

• A Large-Area Search for Low Mass Objects in Upper Scorpius I: The Photometric Campaign and New Brown Dwarfs

Cited by in corpus (15)

• Near-infrared cross-dispersed spectroscopy of brown dwarf candidates in the Upper Sco association
• A Large-Area Search for Low-Mass Objects in Upper Scorpius II: Age and Mass Distributions
• Refining the Census of the Upper Scorpius Association with Gaia
• Zodiacal Exoplanets in Time (ZEIT) V: A Uniform Search for Transiting Planets in Young Clusters Observed by K2
• Substellar Objects in Nearby Young Clusters (SONYC): The bottom of the Initial Mass Function in NGC1333
• A Census of the Stellar Populations in the Sco-Cen Complex
• Proper motion L and T dwarf candidate members of the Pleiades
• The optical+infrared L dwarf spectral sequence of young planetary-mass objects in the Upper Scorpius association
• The UKIDSS-2MASS Proper Motion Survey I: Ultracool dwarfs from UKIDSS DR4
• Near Infrared Spectroscopy of Young Brown Dwarfs in Upper Scorpius
• USco1621 B and USco1556 B: Two wide companions at the deuterium-burning mass limit in Upper Scorpius
• Exploring the planetary-mass population in the Upper Scorpius association
• Angular Momentum Evolution of Young Stars in the Nearby Scorpius-Centaurus OB Association
• Strong H$\alpha$ emission in the young planetary mass companion 2MASS J0249-0557 c
• Spectroscopy of Candidate Members of the Sco-Cen Complex