Discovery of the first wide L dwarf giant binary system and eight other ultra-cool dwarfs in wide binaries - Astrophysics > Astrophysics of GalaxiesReport as inadecuate




Discovery of the first wide L dwarf giant binary system and eight other ultra-cool dwarfs in wide binaries - Astrophysics > Astrophysics of Galaxies - Download this document for free, or read online. Document in PDF available to download.

Abstract: We identify 806 ultra-cool dwarfs from their SDSS riz photometry of which 34are newly discovered L dwarfs and obtain proper motions through cross matchingwith UKIDSS and 2MASS. Proper motion and distance constraints show that nine ofour ultra-cool dwarfs are members of widely separated binary systems; SDSS 0101K5V+M9.5V, SDSS 0207 M1.5V+L3V, SDSS 0832 K3III+L3.5V, SDSS 0858M4V+L0V, SDSS 0953 M4V+M9.5V, SDSS 0956 M2V+M9V, SDSS 1304 M4.5V+L0V,SDSS 1631 M5.5V+M8V, SDSS 1638 M4V+L0V. One of these SDSS 0832 is shownto be a companion to the bright K3 giant Eta Cancri. Such primaries can provideage and metallicity constraints for any companion objects, yielding excellentbenchmark objects. Eta Cancri AB is the first wide ultra-cool dwarf + giantbinary system identified. We present new observations and analysis thatconstrain the metallicity of Eta Cancri A to be near solar, and use recentevolutionary models to constrain the age of the giant to be 2.2-6.1 Gyr. If EtaCancri B is a single object, we estimate its physical attributes to be; mass =63-82 M Jup, T eff = 1800+-150 K, log g = 5.3-5.5, M-H = 0.0+-0.1. Itscolours are non typical when compared to other ultra-cool dwarfs, and we alsoassess the possibility that Eta Cancri B is itself an unresolved binary,showing that the combined light of an L4 + T4 system could provide a reasonableexplanation for its colours.



Author: Z.H. Zhang, D. J. Pinfield, A. C. Day-Jones, B. Burningham, H. R. A. Jones, S. Yu, J. S. Jenkins, Z. Han, M. C. Galvez-Ortiz, J.

Source: https://arxiv.org/







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