No Neutron Star Companion To The Lowest Mass SDSS White Dwarf (2009)
Agueros, Marcel, Heinke, Craig, Camilo, Fernando, Kilic, Mukremin, Anderson, Scott, Freire, Paulo, ...
SDSS J091709.55+463821.8 (hereafter J0917+4638) is the lowest surface gravity white dwarf (WD) currently known, with log g = 5.55 +/- 0.05 (M ~ 0.17 M_sun; Kilic et al. 2007a,b). Such low-mass white...
Kirkpatrick, J. Davy, Cruz, Kelle L., Barman, Travis S., Burgasser, Adam J., Looper, Dagny L., Tinney, C. G., ...
Using a large sample of optical spectra of late-type dwarfs, we identify a subset of late-M through L field dwarfs that, because of the presence of low-gravity features in their spectra, are believed...
Meeting the cool neighbors. X. Ultracool dwarfs from the 2MASS All-Sky data reslease (2008)
Reid, I. Neill, Cruz, Kelle L., Kirkpatrick, J. Davy, Allen, Peter R., Mungall, F., Liebert, James, ...
Using data from the 2 Micron All Sky Survey All-Sky Point Source Catalogue, we have extended our census of nearby ultracool dwarfs to cover the full celestial sphere above Galactic latitude of 15°....
Kirkpatrick, J. Davy, Cruz, Kelle L., Barman, Travis S., Burgasser, Adam J., Looper, Dagny L., Tinney, C. G., ...
Using a large sample of optical spectra of late-type dwarfs, we identify a subset of late-M through L field dwarfs that, because of the presence of low-gravity features in their spectra, are believed...
Meeting the Cool Neighbors X: Ultracool dwarfs from the 2MASS All-Sky Data Release (2008)
Reid, I. Neill, Cruz, Kelle L., Kirkpatrick, J. Davy, Allen, Peter R., Mungall, F., Liebert, James, ...
Using data from the 2MASS All-Sky Point Source Catalogue, we have extended our census of nearby ultracool dwarfs to cover the full celestial sphere above Galactic latitute 15 degrees. Starting with...
SDSS J142625.71+575218.3, a Prototype for a New Class of Variable White Dwarf (2008)
Montgomery, M. H., Williams, Kurtis A., Winget, D. E., Dufour, Patrick, Degennaro, Steven, Liebert, James
We present the results of a search for pulsations in six of the recently discovered carbon-atmosphere white dwarf ("hot DQ") stars. Based on our theoretical calculations, the star SDSS...
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...
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...
Rare White dwarf stars with carbon atmospheres (2007)
Dufour, P., Liebert, James, Fontaine, G., Behara, N.
White dwarfs represent the endpoint of stellar evolution for stars with initial masses between approximately 0.07 msun and 8-10 msun, where msun is the mass of the Sun (more massive stars end their...
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...
Silvestri, Nicole M., Lemagie, Mara P., Hawley, Suzanne L., West, Andrew A., Schmidt, Gary D., Liebert, James, ...
We present the latest catalog of more than 1200 spectroscopically-selected close binary systems observed with the Sloan Digital Sky Survey through Data Release Five. We use the catalog to search for...
Dufour, P., Bergeron, P., Liebert, James, Harris, H. C., Knapp, G. R., Hall, Patrick B., ...
We present a detailed analysis of a large spectroscopic and photometric sample of DZ white dwarfs based on our latest model atmosphere calculations. We revise the atmospheric parameters of the...
Cruz, Kelle L., Reid, I. Neill, Kirkpatrick, J. Davy, Burgasser, Adam J., Liebert, James, Solomon, Adam R., ...
We present a 20 pc, volume-limited sample of M7-L8 dwarfs created through spectroscopic follow-up of sources selected from the Two Micron All Sky Survey Second Incremental Release Point Source...
Activity and Kinematics of Ultracool Dwarfs Including An Amazing Flare Observation (2007)
Schmidt, Sarah J., Cruz, Kelle L., Bongiorno, Bethany J., Liebert, James, Reid, I. Neill
We present the activity and kinematics of a representative volume-limited (20 pc) sample of 152 late-M and L dwarfs (M7--L8) photometrically selected from the Two Micron All-Sky Survey (2MASS). Using...
On the Nature of the Unique H$\alpha$-Emitting T Dwarf 2MASS J12373919+6526148 (2006)
Liebert, James, Burgasser, Adam J.
We explore and discount the hypothesis that the strong, continual H$\alpha$-emitting T dwarf 2MASS J12373919+6526148 can be explained as a young, low gravity, very low mass brown dwarf. The source is...
The Pre-cataclysmic Binary HS 1136+6646 May Have a Companion (2006)
Liebert, James, Williams, Kurtis A., Holberg, J. B., Sing, D. K.
Because of the similarity of the primary star of HS 1136+6646 to the planetary nebula central star BE Ursae Majoris, we did wide field imaging of the former with an H-alpha filter. No nebulosity was...
Cruz, Kelle L., Reid, I. Neill, Kirkpatrick, J. Davy, Burgasser, Adam J., Liebert, James, Solomon, Adam R., ...
We present a 20-pc, volume-limited sample of M7-L8 dwarfs created through spectroscopic follow-up of sources selected from the Two Micron All Sky Survey (2MASS) Second Incremental Release Point...
Using the Galactic Dynamics of M7 Dwarfs to Infer the Evolution of Their Magnetic Activity (2006)
West, Andrew A., Bochanski, John J., Hawley, Suzanne L., Cruz, Kelle L., Covey, Kevin R., Silvestri, Nicole M., ...
We present a spectroscopic study and dynamical analysis of ~2600 M7 dwarfs. We confirm our previous finding that the fraction of magnetically active stars decreases with vertical distance from the...
Model Atmosphere Analysis of the Weakly Magnetic DZ White Dwarf G165-7 (2006)
Dufour, P., Bergeron, P., Schmidt, G. D., Liebert, James, Harris, H. C., Knapp, G. R., ...
A reanalysis of the strongly metal-blanketed DZ white dwarf G165-7 is presented. An improved grid of model atmospheres and synthetic spectra is used to analyze BVRI, JHK, and ugriz photometric...
Eisenstein, Daniel J., Liebert, James, Harris, Hugh C., Kleinmann, S. J., Nitta, Atsuko, Silvestri, Nicole, ...
We present a catalog of 9316 spectroscopically confirmed white dwarfs from the Sloan Digital Sky Survey Data Release 4. We have selected the stars through photometric cuts and spectroscopic modeling,...
Hot DB White Dwarfs from the Sloan Digital Sky Survey (2006)
Eisenstein, Daniel J., Liebert, James, Koester, Detlev, Kleinmann, S. J., Nitta, Atsuko, Smith, Paul S., ...
We present ugriz photometry and optical spectroscopy for 28 DB and DO white dwarfs with temperatures between 28,000K and 45,000K. About 10 of these are particularly well-observed; the remainder are...
Spitzer/IRAC Photometry of M, L, and T Dwarfs (2006)
Patten, Brian M., Stauffer, John R., Burrows, Adam, Marengo, Massimo, Hora, Joseph L., Luhman, Kevin L., ...
We present the results of a program to acquire photometry for eighty-six late-M, L, and T dwarfs using the Infrared Array Camera (IRAC) on the Spitzer Space Telescope. We examine the behavior of...
Burgasser, Adam J., Kirkpatrick, J. Davy, Cruz, Kelle L., Reid, I. Neill, Leggett, Sandy K., Liebert, James, ...
We present the results of a Hubble Space Telescope NICMOS imaging survey of 22 T-type field brown dwarfs. Five are resolved as binary systems with angular separations of 0"05-0"35, and companionship...
A Hot DQ White Dwarf in the Open Star Cluster M35 (2006)
Williams, Kurtis A., Liebert, James, Bolte, Michael, Hanson, Robert B.
We report the discovery of a hot DQ white dwarf, NGC 2168:LAWDS 28, that is a likely member of the 150-Myr old cluster NGC 2168 (Messier 35). The spectrum of the white dwarf is dominated by CII...
Adam J. Burgasser, J. Davy Kirkpatrick, Kelle L. Cruz, I. Neill Reid, Y K. Leggett, James Liebert, ...
We present the results of a Hubble Space Telescope NICMOS imaging survey of 22 T-type field brown dwarfs. Five are resolved as binary systems with angular separations of 0B05Y0B35, and companionship...
The White Dwarf Luminosity Function from SDSS Imaging Data (2005)
Harris, Hugh C., Munn, Jeffrey A., Kilic, Mukremin, Liebert, James, Williams, Kurtis A., Von Hippel, Ted, ...
A sample of white dwarfs is selected from SDSS DR3 imaging data using their reduced proper motions, based on improved proper motions from SDSS plus USNO-B combined data. Numerous SDSS and followup...
SDSS J042348.57-041403.5AB: A Brown Dwarf Binary Straddling the L/T Transition (2005)
Burgasser, Adam J., Reid, I. Neill, Leggett, S. K., Kirkpatrick, J. Davy, Liebert, James, Burrows, Adam
We present the discovery of SDSS J042348.57-041403.5 as a closely-separated (0"16) brown dwarf binary, resolved by the Hubble Space Telescope Near Infrared Camera and Multi-Object Spectrometer....
The Age and Progenitor Mass of Sirius B (2005)
Liebert, James, Young, Patrick A., Arnett, David, Holberg, J. B., Williams, Kurtis A.
The Sirius AB binary system has masses that are well determined from many decades of astrometric measurements. Because of the well-measured radius and luminosity of Sirius A, we employed the TYCHO...
Magnetic White Dwarfs from the SDSS II. The Second and Third Data Releases (2005)
Vanlandingham, Karen M., Schmidt, Gary D., Eisenstein, Daniel J., Harris, Hugh C., Anderson, Scott F., Hall, Pat B., ...
Fifty-two magnetic white dwarfs have been identified in spectroscopic observations from the Sloan Digital Sky Survey (SDSS) obtained between mid-2002 and the end of 2004, including Data Releases 2...
Cool White Dwarfs in the Sloan Digital Sky Survey (2005)
Kilic, Mukremin, Munn, Jeffrey A., Harris, Hugh C., Liebert, James, Von Hippel, Ted, Williams, Kurtis A., ...
A reduced proper motion diagram utilizing Sloan Digital Sky Survey (SDSS) photometry and astrometry and USNO-B plate astrometry is used to separate cool white dwarf candidates from metal-weak,...
Williams, Kurtis A., Bolte, Michael, Liebert, James
We present spectroscopic observations of the remaining four candidate white dwarfs in Praesepe. All four candidates are quasars with redshifts between 0.8 and 2.8. One quasar, LB 6072, is observed to...
Discovery of New Ultracool White Dwarfs in the Sloan Digital Sky Survey (2004)
Gates, Evalyn, Gyuk, Geza, Harris, Hugh C., Subbarao, Mark, Anderson, Scott, Kleinman, S. J., ...
We report the discovery of five very cool white dwarfs in the Sloan Digital Sky Survey (SDSS). Four are ultracool, exhibiting strong collision induced absorption (CIA) from molecular hydrogen and are...
A Helium White Dwarf of Extremely Low Mass (2004)
Liebert, James, Bergeron, P., Eisenstein, Daniel, Harris, H. C., Kleinman, S. J., Nitta, Atsuko, ...
We analyze the spectrum of an unusually-low mass white dwarf, SDSSJ123410.37-022802.9 (0335-264-52000), found in our recent, white dwarf catalog from the SDSS DR1 data release. Two independent, model...
Kleinman, S. J., Harris, Hugh C., Eisenstein, Daniel J., Liebert, James, Nitta, Atsuko, Krzesiński, Jurek, ...
We present the full spectroscopic white dwarf and hot subdwarf sample from the SDSS first data release, DR1. We find 2551 white dwarf stars of various types, 240 hot subdwarf stars, and an additional...
2MASS J05185995-2828372: Discovery of an Unresolved L/T Binary (2004)
Cruz, Kelle L., Burgasser, Adam J., Reid, I. Neill, Liebert, James
We present the peculiar near-infrared spectrum of the newly discovered brown dwarf 2MASS J05185995-2828372, identified in the Two Micron All-Sky Survey. Features characteristic of both L and T dwarfs...
Meeting the Cool New Neighbors V: A 2MASS-Selected Sample of Ultracool Dwarfs (2003)
Cruz, Kelle L., Reid, I. Neill, Liebert, James, Kirkpatrick, J. Davy, Lowrance, Patrick J.
We present initial results of our effort to create a statistically robust, volume-limited sample of ultracool dwarfs from the 2MASS Second Incremental Data Release. We are engaged in a multifaceted...
The Spectra of T Dwarfs. II. Red Optical Data (2003)
Burgasser, Adam J., Kirkpatrick, J. Davy, Liebert, James, Burrows, Adam
We present 6300--10100 {\AA} spectra for a sample of 13 T dwarfs observed using LRIS mounted on the Keck I 10m Telescope. A variety of features are identified and analyzed, including...
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 =...
Blue Horizontal Branch Stars in Old, Metal-Rich Stellar Systems (2003)
Peterson, Ruth C., Carney, Bruce W., Dorman, Ben, Green, Elizabeth M., Landsman, Wayne, Liebert, James, ...
Twenty years ago, Burstein et al. (1984)suggested that strong CN and Hbeta absorption meant younger ages among globular clusters in the Andromeda galaxy (M31), unless blue stars above the...
The Discovery of Two Nearby Carbon Dwarfs (2003)
Lowrance, Patrick J., Kirkpatrick, J. Davy, Reid, I. Neill, Cruz, Kelle L., Liebert, James
The comparison of optical and 2MASS near-infrared photometry for large samples of catalogued proper motion stars has the potential to discover previously unrecognized nearby objects of rare type. In...
The True Incidence of Magnetism among Field White Dwarfs (2002)
Liebert, James, Bergeron, P., Holberg, J. B.
We study the incidence of magnetism in white dwarfs from three large and well-observed samples of hot, cool, and nearby white dwarfs in order to test whether the fraction of magnetic degenerates is...
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...
Post-T Tauri Stars in the Nearest OB Association (2002)
Mamajek, Eric E., Meyer, Michael R., Liebert, James
We present results of a spectroscopic survey of X-ray- and proper motion-selected samples of late-type stars in the Lower Cen-Cru (LCC) and Upper Cen-Lup (UCL) subgroups of the nearest OB...
Close, Laird M., Siegler, Nick, Potter, Dan, Brandner, Wolfgang, Liebert, James
Use of the highly sensitive Hokupa'a/Gemini curvature wavefront sensor has allowed for the first time direct adaptive optics (AO) guiding on M8-M9 very low mass (VLM) stars. An initial survey of 20...
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...
A spectroscopic analysis of the DAB white dwarf PG 1115+166 is presented. The observed hydrogen and helium line profiles are shown to be incompatible with model spectra calculated under the...
Theoretical Spectral Models of T Dwarfs at Short Wavelengths and Their Comparison with Data (2001)
Burrows, Adam, Burgasser, Adam J., Kirkpatrick, J. Davy, Liebert, James, Milsom, J. A., Sudarsky, David, ...
We have generated new, self-consistent spectral and atmosphere models for the effective temperature range 600 K to 1300 K thought to encompass the known T dwarfs. For the first time, theoretical...
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...
Three newly-discovered M-dwarf companions of Solar Neighbourhood stars (2001)
Kirkpatrick, J. Davy, Liebert, James, Cruz, K. L., Gizis, J. E., Reid, I. Neill
We present low-resolution spectroscopy of newly-discovered candidate companions to three stars in the Solar Neighbourhood. All three companions are M dwarfs, with spectral types ranging from M4 to...
Observational Tests and Predictive Stellar Evolution (2001)
Young, P. A., Mamajek, E. E., Arnett, David, Liebert, James
We compare eighteen binary systems with precisely determined radii and masses from 23 to 1.1 M_sol, and stellar evolution models produced with our newly revised code TYCHO. ``Overshooting'' and...
The Theory of Brown Dwarfs and Extrasolar Giant Planets (2001)
Burrows, Adam, Hubbard, W. B., Lunine, J. I., Liebert, James
Straddling the traditional realms of the planets and the stars, objects below the edge of the main sequence have such unique properties, and are being discovered in such quantities, that one can...
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...
Discovery of a Magnetic DZ White Dwarf with Zeeman-Split Lines of Heavy Elements (2000)
Reid, I. Neill, Liebert, James, Schmidt, Gary D.
A spectroscopic survey of previously-unstudied Luyten Half Second proper motion stars has resulted in the discoveries of two new cool magnetic white dwarfs. One (LHS 2273) is a routine DA star, T=...
On the Origin of Subdwarf B Stars and Related Metal-Rich Binaries (2000)
Green, Elizabeth M., Liebert, James, Saffer, Rex A.
Mounting evidence from subdwarf B (sdB) stars in the galactic field and their recently discovered counterparts in old open clusters indicates that at least two thirds of local disk sdB stars are...
A Survey for Faint Stars of Large Proper Motion Using Extra Poss II Plates (2000)
Monet, David G., Fisher, Matthew D., Liebert, James, Canzian, Blaise, Harris, Hugh C., Reid, I. Neill
We have conducted a search for new stars of high proper motion ($\geq$0.4 arcsec yr$^{-1}$) using POSS II fields for which an extra IIIaF (red) plate of good quality exists, along with useable IIIaJ...
New Neighbors from 2MASS: Activity and Kinematics at the Bottom of the Main Sequence (2000)
Gizis, John E., Monet, David G., Reid, I. Neill, Kirkpatrick, J. Davy, Liebert, James, Williams, Rik J.
We have combined 2MASS and POSS II data in a search for nearby ultracool (later than M6.5) dwarfs with K_s6 Angstroms) ultracool M dwarfs are consistent with an ordinary old disk stellar population,...
Sixty-seven Additional L Dwarfs Discovered by the Two Micron All Sky Survey (2MASS) (2000)
Kirkpatrick, J. Davy, Reid, I. Neill, Liebert, James, Gizis, John E., Burgasser, Adam J., Monet, David G., ...
We present JHKs photometry, far red spectra, and spectral classifications for an additional 67 L dwarfs discovered by the Two Micron All Sky Survey. One of the goals of this new search was to locate...
Detection of H Alpha Emission in a Methane (T-Type) Brown Dwarf (2000)
Burgasser, Adam J., Kirkpatrick, J. Davy, Reid, I. Neill, Liebert, James, Gizis, John E., Brown, Michael E.
We report the detection of H{$\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...
Reid, I. Neill, Kirkpatrick, J. Davy, Gizis, J. E., Dahn, C. C., Monet, D. G., Williams, R. J., ...
We present spectroscopic, photometric and astrometric observations of four bright L dwarfs identified in the course of the 2MASS near-infrared survey. Our spectroscopic data extend to wavelengths...
A Very Low-Luminosity, Very Cool, DC White Dwarf (1999)
Harris, Hugh, Dahn, Conard, Vrba, Frederick, Henden, Arne, Liebert, James, Schmidt, Gary, ...
The star LHS 3250 is found to be a white dwarf at a distance of 30 pc. Its absolute magnitudes (M_V = 15.72; M_bol = 16.2) put it among the least-luminous white dwarfs known. Its optical spectrum...
On the Nature of the Peculiar Hot Star in the Young LMC Cluster NGC1818 (1999)
The blue star reported in the field of the young LMC cluster NGC1818 by Elson et al. (1998) has the wrong luminosity and radius to be a "luminous white dwarf" member of the cluster. In addition,...
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 Age, Extinction and Distance of the Old, Metal-Rich Open Cluster NGC 6791 (1998)
Chaboyer, Brian, Green, Elizabeth M., Liebert, James
An extensive grid of metal-rich isochrones utilizing the latest available input physics has been calculated for comparison with the old, metal-rich open cluster NGC 6791. The isochrones have been...
Brown Dwarfs: From Mythical to Ubiquitous (1998)
Astrophysical objects below the stellar mass limit but well above the mass of Jupiter eluded discovery for nearly three decades after Kumar first proposed their existence, and for two decades after...
Discovery of New Ultracool White Dwarfs in the Sloan Digital Sky Survey (1998)
Gates, Evalyn, Gyuk, Geza, Harris, Hugh D., Subbarao, Mark, Anderson, Scott, Kleinman, S. J., ...
We report the discovery of five new white dwarfs in the Sloan Digital Sky Survey. Four are ultracool, exhibiting strong collision-induced absorption (CIA) from molecular hydrogen and are similar in...
The White Dwarf Luminosity Function from Sloan Digital Sky Survey Imaging Data (1998)
Harris, Hugh C., Munn, Jeffrey A., Kilic, Mukremin, Liebert, James, Kleinman, S. J., Metcalfe, T. S., ...
A sample of white dwarfs is selected from the Sloan Digital Sky Survey (SDSS) Data Release 3 using their reduced proper motions, based on improved proper motions from combined SDSS and USNO-B data....
Understanding the Cool DA White Dwarf, G29-38 (1997)
Kleinman, S. J., Nather, R. E., Winget, D. E., Clemens, J. C., Bradley, P. A., Kanaan, A., ...
The white dwarfs are promising laboratories for the study of cosmochronology and stellar evolution. Through observations of the pulsating white dwarfs, we can measure their internal structures and...
Discovery of Extended Blue Horizontal Branches in Two Metal-Rich Globular Clusters (1997)
Rich, R. Michael, Sosin, Craig, Djorgovski, S. George, Piotto, Giampaolo, King, Ivan R., Renzini, Alvio, ...
We have used WFPC2 to construct B, V color-magnitude diagrams of four metal-rich globular clusters, NGC 104 (47 Tuc), NGC 5927, NGC 6388, and NGC 6441. All four clusters have well populated red...
Peculiar Multimodality on the Horizontal Branch of the Globular Cluster NGC 2808 (1997)
Sosin, Craig, Dorman, Ben, Djorgovski, S. George, Piotto, Giampaolo, Rich, R. Michael, King, Ivan R., ...
We present distributions of colors of stars along the horizontal branch of the globular cluster NGC 2808, from Hubble Space Telescope WFPC2 imaging in B, V, and an ultraviolet filter (F218W). This...
Renzini, Alvio, Bragaglia, Angela, Ferraro, Francesco R., Gilmozzi, Roberto, Ortolani, Sergio, Holberg, J. B., ...
Deep Hubble Space Telescope (HST) observations with WFPC2 of the nearby globular cluster NGC 6752 have allowed us to obtain accurate photometry for the cluster white dwarfs (WD). A sample of local...