相关论文: The Onset of Methane in L Dwarfs

New 3.3--3.6~$\mu$m spectra were obtained of nine young stellar objects embedded in molecular clouds. An absorption feature at $\sim$3.47~$\mu$m (2880~cm$^{-1}$) with FWHM$\sim$0.09 $\mu$m (80 cm$^{-1}$), first identified by Allamandola et…

We present the discovery of 11 new T dwarfs, found during the course of a photometric survey for mid-to-late T dwarfs in the 2MASS Point Source Catalog and from a proper motion selected sample of ultracool dwarfs in the 2MASS Working…

We present the spectroscopic analysis of a large sample of late-M, L, and T dwarfs from UKIDSS. Using the YJHK photometry from ULAS and the red-optical photometry from SDSS we selected a sample of 262 brown dwarf candidates and we…

The detection of the 6.7 GHz line of methanol (CH3OH) is reported for the first time toward an object beyond the Magellanic Clouds. Using the Effelsberg 100 m telescope, two absorption features were identified toward the Seyfert 2 galaxy…

We report the discovery of a new, polluted, magnetic white dwarf in the Luyten survey of high-proper motion stars. High-dispersion spectra of NLTT 7547 reveal a complex heavy element line spectrum in a cool (~5 200 K) hydrogen-dominated…

We present opacity sampling model atmospheres, synthetic spectra and colors for brown dwarfs and very low mass stars in two limiting case of dust grain formation: 1) inefficient gravitational settling i.e. the dust is distributed according…

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 present simultaneous, multiband monitoring of 19 field M dwarfs (spectral types M2-M9). Significant variability was found in seven objects in at least one out of the three channels I, R and G. Two objects, LHS370 (M5V) and 2M1707+64…

We present initial results from a wide-field (30,000 deg^2) search for L/T transition brown dwarfs within 25 pc using the Pan-STARRS1 and WISE surveys. Previous large-area searches have been incomplete for L/T transition dwarfs, because…

We present new groundbased 3 $\mu$m spectra of 14 young stellar objects with H_2O ice absorption bands. The broad absorption feature at 3.47 $\mu$m was detected toward all objects and its optical depth is correlated with the optical depth…

We report the detection of 13 heavy elements (Na, Mg, Al, Si, Ca, Ti, Cr, Mn, Fe, Co, Ni, Cu, and Sr) in the photosphere of LSPM J0207+3331, a ~3 Gyr old hydrogen-rich white dwarf with an effective temperature comparable to that of the Sun.…

We report the discovery and classification of SDSS~J053341.43+001434.1 (SDSS0533), an early-L dwarf first discovered during a powerful $\Delta V < -11$ magnitude flare observed as part of the ASAS-SN survey. Optical and infrared…

The detection of the CO_2 absorption band at 4.2 {\mu}m in brown dwarf spectra by AKARI has made it possible to discuss CO_2 molecular abundance in brown dwarf atmospheres. In our previous studies, we found an excess in the 4.2 {\mu}m CO_2…

About a dozen hot white dwarfs with effective temperatures Teff = 65,000-120,000 K exhibit unusual absorption features in their optical spectra. These objects were tentatively identified as Rydberg lines of ultra-high excited metals in…

Absorption and emission lines originating from the nu3 C-H stretching manifold of gas phase CH4 were discovered in the high resolution (R=25,000) infrared L band spectrum along the line of sight toward NGC 7538 : IRS9. These observations…

Condensate clouds strongly impact the spectra of brown dwarfs and exoplanets. Recent discoveries of variable L/T transition dwarfs argued for patchy clouds in at least some ultracool atmospheres. This study aims to measure the frequency and…

We present the discovery of a companion to the Y-dwarf, CWISEP J193518.59-154620.3, the second Y-Y dwarf binary detected to date. Y-dwarfs are the coldest known free-floating objects ($<$ 500 K) and on average represent the lowest mass…

We present near-infrared observations of 71 newly discovered L and T dwarfs, selected from imaging data of the Sloan Digital Sky Survey (SDSS) using the i-dropout technique. Sixty-five of these dwarfs have been classified spectroscopically…

In recent years, JWST has facilitated detections of carbon-bearing molecules in the atmospheres of temperate sub-Neptunes orbiting M dwarfs, ushering in a new era in the characterization of this intriguing planetary regime. We report the…

We have used the ATNF Mopra antenna and the SEST antenna to search in the directions of several class II methanol maser sources for emission from six methanol transitions in the frequency range 85-115 GHz. The transitions were selected from…