相关论文: Characterization of High Proper Motion Objects fro…

Context. Metal-poor brown dwarfs are poorly understood because they are extremely faint and rare. Only a few candidates have been identified as T-type subdwarfs in infrared surveys and their optical properties remain unconstrained. Aims. We…

The status of 38 halo white dwarf candidates identified by Oppenheimer et al. (2001) has been intensively discussed by various authors. In analyses undertaken to date, trigonometric parallaxes are crucial missing data. Distance measurements…

We conducted a spectropolarimetic survey of 58 high proper-motion white dwarfs which achieved uncertainties of >2 kG in the Halpha line and >5 kG in the upper Balmer line series. The survey aimed at detecting low magnetic fields (< 100 kG)…

We present near-infrared spectra for a sample of T dwarfs, including eleven new discoveries made using the Two Micron All Sky Survey. These objects are distinguished from warmer (L-type) brown dwarfs by the presence of methane absorption…

In this paper, we describe how to use the Maximum Reduced Proper Motion method (Phan-Bao et al. 2003) to detect 57 nearby L and late-M dwarfs (d_phot <= 30 pc): 36 of them are newly discovered. Spectroscopic observations of 43 of the 57…

We present near-infrared (1.15-2.50 microns) medium-resolution (R = 1700) spectroscopy of a sample of 23 brown dwarf candidates in the young Upper Sco association. We confirm membership of 21 brown dwarfs based on their spectral shape,…

Proper motions with values >10 mas/yr or <-10 mas/yr have been extracted from the USNO-B1.0 and Tycho II catalogues for all Lanning UV-bright sources identified in the Sandage Two-color Survey of the Galactic Plane and presented in Papers…

We present first results from a targeted search for brown dwarfs with unusual red colors indicative of peculiar atmospheric characteristics. These include objects with low surface gravities or with unusual dust content or cloud properties.…

We report the discovery of a substellar companion to the nearby solar-type star HD 46588 (F7V, 17.9 pc, ~3 Gyr). HD 46588 B was found through a survey for common proper motion companions to nearby stars using data from the Wide-field…

We present results of an optical and near-infrared (IR) 1.8 deg^2 survey in the Pleiades open cluster to search for substellar objects. From optical I-band images from the CFHT and J-band images from the 3.5 m CAHA Telescope, we identify 18…

We present the discovery of the first L-type subdwarf, 2MASS J05325346+8246465. This object exhibits enhanced collision-induced H$_2$ absorption, resulting in blue NIR colors ($J-K_s = 0.26{\pm}0.16$). In addition, strong hydride bands in…

Our goal is to characterise the physical properties of the metal-poor brown dwarf population. In particular, we focus on the recently discovered peculiar dwarf WISE J1810055$-$1010023. We collected optical iz and near-infrared J-band…

We present the discovery of a very cold, very low mass, nearby brown dwarf using data from the NASA Wide-field Infrared Survey Explorer (WISE). The object, WISE J064723.23-623235.5, has a very red WISE color of W1-W2 > 3.77 mag and a very…

We examine 14 hot white dwarfs for signs of infrared excess using the Spitzer Space Telescope. Twelve of the objects are massive white dwarfs which have been suggested to be the result of binary mergers. The remaining two objects are…

Our aim is to identify brown dwarf members of the nearby Hyades open star cluster to determine the photometric and spectroscopic properties of brown dwarfs at moderately old ages and extend the knowledge of the substellar mass function of…

We present the discovery of seven ultracool brown dwarfs identified with the Wide-field Infrared Survey Explorer (WISE). Near-infrared spectroscopy reveals deep absorption bands of H_2O and CH_4 that indicate all seven of the brown dwarfs…

We report the discovery of a nearby, old, halo white dwarf candidate from the Sloan Digital Sky Survey. SDSS J110217.48+411315.4 has a proper motion of 1.75 arcsec/year and redder optical colors than all other known featureless (type DC)…

We report the discovery of an unusually red brown dwarf found in a search for high proper motion objects using WISE and 2MASS data. WISEP J004701.06+680352.1 is moving at 0.44$ arcsec/yr and lies relatively close to the Galactic Plane…

We present an analysis of 23 L dwarfs whose optical spectra display unusual features. Twenty-one were uncovered during our search for nearby, late-type objects using the Two Micron All-Sky Survey while two were identified in the literature.…

We aim at performing a kinematic census of young stellar objects (YSOs) in the Rho Ophiuchi F core and partially in the E core of the L1688 dark cloud. We run a proper motion program at the ESO New Technology Telescope (NTT) with the Son of…