Adam J. Burgasser, J. Davy Kirkpatrick, Michael E. Brown, I. Neill Reid, Adam Burrows, James Liebert, ...
We present near-infrared spectra for a sample of T dwarfs, including 11 new discoveries made using the 2 Micron All Sky Survey. These objects are distinguished from warmer (L-type) brown dwarfs by...
J. Davy Kirkpatrick, I. Neil Reid, James Liebert, John E. Gizis, Adam J. Burgasser, G. Monet, ...
We present JHK, photometry, far red spectra, and spectral classifications for an additional 67 L dwarfs discovered by the Two Micron All Sky Survey. One of the goals of this new search was to locate...
John E. Gizis, J. Davy Kirkpatrick, John C. Wilson
We report the discovery of a probable brown dwarf companion to the nearby K2 dwarf GJ 1048 using the Two Micron All-Sky Survey (2MASS). This source, 2MASSI 50235599-233120 or GJ 1048B, has 2MASS...
Adam J. Burgasser, J. Davy Kirkpatrick, I. Neill Reid, James Liebert, John E. Gizis, Michael E. Brown
We report the detection of Hff emission in the T dwarf (methane brown dwarf) 2MASSW J1237392+652615 over three days using the Keck Low Resolution Imaging Spectrograph. The measured line flux, log(L...
John E. Gizis, J. Davy Kirkpatrick, Adam Burgasser, I. Neill Reid, David G. Monet, James Liebert, ...
We use three field L and T dwarfs that were discovered to be wide companions to known stars by the Two Micron All-Sky Survey to derive a preliminary brown dwarf companion frequency. Observed L and T...
HST search for M subdwarf binaries (2007)
Riaz, Basmah, Gizis, John E., Samaddar, Debasmita
We present HST/ACS observations of 19 nearby M subdwarfs in a search for binary systems. Other than the wide common proper motion pair LHS 2140/2139, none of our sdM and esdM targets are found to be...
The Trigonometric Parallax of the Brown Dwarf Planetary System 2MASSW J1207334-393254 (2007)
Gizis, John E., Jao, Wei-Chun, Subasavage, John P., Henry, Todd J.
We have measured a trigonometric parallax to the young brown dwarf 2MASSW J1207334-393254. The distance [54.0 (+3.2,-2.8) pc] and space motion confirm membership in the TW Hydrae Association. The...
Characterizing the disk around the TW Hydrae Association brown dwarf 2MASSW J1207334-393254 (2007)
We present detailed modeling of the disk around the TW Hydrae Association (TWA) brown dwarf 2MASSW J1207334-393254 (2M1207), using {\it Spitzer} observations from 3.6 to 24 $\micron$. The spectral...
Infrared observations of a mid-L dwarf with strong H$\alpha$ emission (2006)
We present {\it Spitzer}/IRAC observations of the L5 dwarf, 2MASSI J1315309-264951 (2M1315). This ultracool dwarf is known to display strong emission in the H$\alpha$ line. The SED for this object...
Spitzer Observations of Nearby M Dwarfs (2006)
Riaz, Basmah, Mullan, D. J., Gizis, John E.
We present Spitzer IRAC and MIPS observations for a sample of eight M dwarfs: six dMe, one dM, and one sdMe star. All of our targets are found to have SEDs which are fitted within the error bars by a...
Spitzer Observations of two TW Hydrae Association Brown Dwarfs (2006)
Riaz, Basmah, Gizis, John E., Hmiel, Abraham
We present Spitzer Space Telescope observations of two TW Hydrae Association brown dwarfs, 2MASSW J1207334-393254 and 2MASSW J1139511-315921, in the IRAC and MIPS 24 micron bands. Based on their IRAC...
Identification of New M Dwarfs in the Solar Neighborhood (2006)
Riaz, Basmah, Gizis, John E., Harvin, James
We present the results from a spectroscopic study of 1080 nearby active M dwarfs, selected by correlating the 2MASS and ROSAT catalogs. We have derived the spectral types and estimated distances for...
First Ultraviolet Spectrum of a Brown Dwarf: Evidence for H_2 Fluorescence and Accretion (2005)
Gizis, John E., Shipman, Harry L., Harvin, James A.
We analyze an HST/STIS ultraviolet spectrum of the young brown dwarf 2MASSW J1207334-393254, a member of the ten million-year old TW Hya Association that has a planetary-mass companion. We detect and...
A Chandra Observation of a TW Hydrae Association Brown Dwarf (2004)
We present Chandra observations of the young brown dwarf 2MASSW J1207334-393254, which is a probable member of the TW Hya association. Although this substellar object has strong H alpha emission, it...
The First Substellar Subdwarf? Discovery of a Metal-poor L Dwarf with Halo Kinematics (2003)
Burgasser, Adam J., Kirkpatrick, J. Davy, Burrows, Adam, Liebert, James, Reid, I. Neill, Gizis, John E., ...
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 ($J-K_s =...
Binarity in Brown Dwarfs: T Dwarf Binaries Discovered with the Hubble Space Telescope WPFC2 (2002)
Burgasser, Adam J., Kirkpatrick, J. Davy, Reid, I. Neill, Brown, Michael E., Miskey, Cherie L., Gizis, John E.
(abridged) We present the discovery of two T dwarf binaries, 2MASS 1225-2739AB and 2MASS 1534-2952AB, identified in a sample of ten T dwarfs imaged with the Hubble Space Telescope Wide Field...
A Flaring L5 Dwarf: The Nature of H\alpha Emission in Very Low Mass (Sub)Stellar Objects (2002)
Liebert, James, Kirkpatrick, J. Davy, Cruz, K. L., Reid, I. Neill, Burgasser, Adam, Tinney, C. G., ...
Time series spectrophotometry of the L5 dwarf 2MASS 01443536-0716142 showed strong H\alpha emission which declined by nearly 75% in four consecutive exposures. The line was not detected in emission...
Brown Dwarfs and the TW Hya Association (2002)
I report the results of a survey for low-mass (0.030
A Search for Variability in the Active T dwarf 2MASS 1237+6526 (2002)
Burgasser, Adam J., Liebert, James, Kirkpatrick, J. Davy, Gizis, John E.
We present spectroscopic and imaging observations of the active T dwarf 2MASS 1237+6526, intended to investigate the emission mechanism of this cool brown dwarf. The H$\alpha$ emission line first...
Effective Temperatures of late L dwarfs and the onset of Methane signatures (2001)
Schweitzer, Andreas, Gizis, John E., Hauschildt, Peter H., Allard, France, Howard, Eric M., Kirkpatrick, J. Davy
We present a spectral analysis of a sample of late L dwarfs. We use our latest model atmospheres and synthetic spectra and optical and K band spectra to determine effective temperatures. We derive...
The Spectra of T Dwarfs I: Near-Infrared Data and Spectral Classification (2001)
Burgasser, Adam J., Kirkpatrick, J. Davy, Brown, Michael E., Reid, I. Neill, Burrows, Adam, Liebert, James, ...
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...
Analysis of Keck HIRES spectra of early L-type dwarfs (2001)
Schweitzer, Andreas, Gizis, John E., Hauschildt, Peter H., Allard, France, Reid, I. Neill
We present analyses of high resolution and medium resolution spectra of early L dwarfs. We used our latest set of model atmospheres to reproduce and analyze the observed features. We can model the...
Brown Dwarf Companions to G-type Stars. I: Gliese 417B and Gliese 584C (2001)
Kirkpatrick, J. Davy, Dahn, Conard C., Monet, David G., Reid, I. Neill, Gizis, John E., Liebert, James, ...
We present astrometric and spectroscopic observations confirming that two nearby G dwarf systems (Gliese 417 = BD+36 2162 and Gliese 584AB = eta CrB AB) have a widely separated, L dwarf, substellar...
Substellar Companions to Main Sequence Stars: No Brown Dwarf Desert at Wide Separations (2001)
Gizis, John E., Kirkpatrick, J. Davy, Burgasser, Adam, Reid, I. Neill, Monet, David G., Liebert, James, ...
We use three field L and T dwarfs which were discovered to be wide companions to known stars by the Two Micron All-Sky Survey (2MASS) to derive a preliminary brown dwarf companion frequency. Observed...
A 2MASS L Dwarf Companion to the Nearby K Dwarf GJ 1048 (2000)
Gizis, John E., Kirkpatrick, J. Davy, Wilson, John C.
We report the discovery of a probable L1 companion to the nearby K2 dwarf GJ 1048 using the Two Micron All-Sky Survey (2MASS). This source, 2MASSI J0235599-233120 or GJ 1048B, has 2MASS near-infrared...
Activity and Kinematics of M and L Dwarfs (2000)
I discuss observations of two traditional age indicators, chromospheric activity and kinematics, in late-M and L dwarfs near the hydrogen-burning limit. The frequency and strength of chromospheric...
The Two Micron All-Sky Survey: Removing the Infrared Foreground (2000)
Gizis, John E., Skrutskie, Michael F.
We introduce the properties of the Two Micron All-Sky Survey (2MASS) survey for IAU Symposium 204. 2MASS is a near-infrared survey of the entire sky characterized by high reliability and...
A search for L dwarf binary systems (2000)
Reid, I. Neill, Gizis, John E., Kirkpatrick, J. Davy, Koerner, D. W.
We present analysis of HST Planetary Camera images of twenty L dwarfs identified in the course of the Two Micron All-Sky Survey. Four of the targets have faint, red companions at separations between...
New Neighbors from 2MASS: Activity and Kinematics at the Bottom of the Main Sequence (2000)
Gizis, John E., Monet, David G., Reid, I. Neill, Kirkpatrick, J. Davy, Liebert, James, Williams, Rik J.
We have combined 2MASS and POSS II data in a search for nearby ultracool (later than M6.5) dwarfs with K_s6 Angstroms) ultracool M dwarfs are consistent with an ordinary old disk stellar population,...
Discovery of a Bright Field Methane (T-type) Brown Dwarf by 2MASS (2000)
Burgasser, Adam J., Wilson, John C., Kirkpatrick, J. Davy, Skrutskie, Michael F., Colonno, Michael R., Enos, Alan T., ...
We report the discovery of a bright (J = 13.83$\pm$0.03) methane brown dwarf, or T dwarf, by the Two Micron All Sky Survey. This object, 2MASSI J0559191-140448, is the first brown dwarf identified by...
Sixty-seven Additional L Dwarfs Discovered by the Two Micron All Sky Survey (2MASS) (2000)
Kirkpatrick, J. Davy, Reid, I. Neill, Liebert, James, Gizis, John E., Burgasser, Adam J., Monet, David G., ...
We present JHKs photometry, far red spectra, and spectral classifications for an additional 67 L dwarfs discovered by the Two Micron All Sky Survey. One of the goals of this new search was to locate...
Detection of H Alpha Emission in a Methane (T-Type) Brown Dwarf (2000)
Burgasser, Adam J., Kirkpatrick, J. Davy, Reid, I. Neill, Liebert, James, Gizis, John E., Brown, Michael E.
We report the detection of H{$\alpha$} emission in the T dwarf (methane brown dwarf) 2MASSW J1237392+652615 over three days using the Keck Low Resolution Imaging Spectrograph. The measured line flux,...
An Improved Red Spectrum of the Methane or T-dwarf SDSS 1624+0029: Role of the Alkali Metals (2000)
Liebert, James, Reid, I. Neill, Burrows, Adam, Burgasser, Adam J., Kirkpatrick, J. Davy, Gizis, John E.
A Keck~II low resolution spectrum shortward of ome-micron is presented for SDSS 1624+0029, the first field methane or T dwarf discovered in the Sloan Digital Sky Survey. Significant flux is detected...
HST Observations of M Subdwarfs (2000)
Gizis, John E., Reid, I. Neill
We present the results of an HST snapshot program to search for very-low-mass stellar companions to nearby M subdwarfs. None of our nine targetted metal-poor primaries have companions more massive...
A 2MASS Survey for Brown Dwarfs Towards the Hyades (1999)
Gizis, John E., Reid, I. Neill, Monet, David G.
We present results of a search for very low mass stars and brown dwarfs towards the central region of the Hyades cluster. Using Two Micron All Sky Survey (2MASS) near-infrared and Second Palomar Sky...
Adam J. Burgasser, J. Davy Kirkpatrick, Michael E. Brown, I. Neill Reid, John E. Gizis, Conard C. Dahn, ...
We report the discovery of four field methane (“T”-type) brown dwarfs using Two Micron All-Sky Survey (2MASS) data. One additional methane dwarf, previously discovered by the Sloan Digital Sky...
The distance to NGC 6397 by M-subdwarf main-sequence fitting (1998)
Reid, I. Neill, Gizis, John E.
Recent years have seen a substantial improvement both in photometry of low luminosity stars in globular clusters and in modelling the stellar atmospheres of late-type dwarfs. We build on these...
Forever Young: High Chromospheric Activity in M subdwarfs (1998)
We present spectroscopic observations of two halo M subdwarfs which have H alpha emission lines. We show that in both cases close companions are the most likely cause of the chromospheric activity in...
The Lower Main Sequence and the Orbital Period Distribution of Cataclysmic Variable Stars (1997)
Clemens, J. Christopher, Reid, I. Neill, Gizis, John E., O'Brien, M. Sean
The color-magnitude diagram of the lower main sequence, as measured from a volume-limited sample of nearby stars, shows an abrupt downward jump between Mv = 12 and 13. This jump indicates that the...
Low-mass Binaries in the Hyades - A scarcity of brown dwarfs (1997)
Reid, I. Neill, Gizis, John E.
We have obtained HST Planetary Camera observations of a total of fifty-three low-mass (M < 0.3 M_solar) members of the Hyades cluster. Nine of these stars are resolved as binaries, with separations...
M Subdwarf Secondaries: A Test of the Metallicity Scale (1997)
Gizis, John E., Reid, I. Neill
We present spectra of three M subdwarfs which are common proper motion companions to F or G subdwarfs of known metallicity. The assumption that the companions have the same composition allows us to...
Probing the LHS Catalog. I. New Nearby Stars and the Coolest Subdwarf (1997)
Gizis, John E., Reid, I. Neill
We present moderate resolution spectroscopy of 112 cool dwarf stars to supplement the observations we have already presented in the Palomar/MSU Nearby-Star Spectroscopic Survey. The sample consists...
M-Subdwarfs: Spectroscopic Classification and the Metallicity Scale (1996)
We present a spectroscopic classification system for M-dwarfs and M-subdwarfs based on quantitative measures of TiO and CaH features in the region 6200 - 7400 Angstroms. Our sample of cool stars...