TODD J. HENRY

B.A. ... Cornell University
Ph.D. ... University of Arizona

Director, RECONS
Principal Investigator, CTIOPI and MASSIF
Principal Investigator for GSU, SMARTS Consortium
Member, Space Interferometry Mission Science Team

Professor of Astronomy, Department of Physics & Astronomy
Georgia State University, Atlanta, GA 30302-4106
phone: 404-413-6054 .......... email: thenry @ chara . gsu . edu

RECONS page CTIOPI page SMARTS page
ASPENS page MASSIF page NStars page

Curriculum Vitae (.pdf format, updated JAN 2008)

Research Programs

RECONS page RECONS: Research Consortium on Nearby Stars
RECONS formed in 1994 with the intent of understanding the nature of the Sun's nearest stellar neighbors, both individually and as a population. The projects described below are all associated with the overall RECONS effort. Our goals are to discover ``missing'' members of the sample of stars within 10 parsecs (32.6 light years) and to characterize all stars within that distance limit. New members are found via astrometric, photometric, and spectroscopic techniques, or through companionship studies at small and large separations. Characterization includes photometry and spectroscopy at both optical and infrared wavelengths, as well as determinations of the luminosity function, mass function, and multiplicity fraction of the nearby stars.
RECONS page CTIOPI: Cerro Tololo Interamerican Observatory Parallax Investigation
The CTIOPI Team is on the hunt to discover nearby white, red, and brown dwarfs that lurk unidentified in the solar neighborhood. Our goal is to discover 150 new nearby southern star systems by determining trigonometric parallaxes accurate to 3 milliarcseconds. Since 1999, we have used the 0.9m telescope at the Cerro Tololo Interamerican Observatory, located in the foothills of the Chilean Andes, to measure the distances to potential nearby stars. CTIOPI started under the auspices of the NOAO Surveys Program and continues via the SMARTS Consortium. Through accurate trigonometric parallax measurements, we hope to increase the population of stars known within 25 pc of the Sun by 20% in the southern sky.
SMARTS page SMARTS: Small and Moderate Aperture Research Telescope System
On 01 February 2003, SMARTS took over responsibility for operation of four telescopes at CTIO. These telescopes include the CTIO 1.5m, CTIO 1.3m (formerly the 2MASS telescope), the Yale 1.0m, and the CTIO 0.9m. Long-term partners in SMARTS include the Association of Universities for Research in Astonomy (NOAO in Tucson, AZ and La Serena, Chile), Georgia State University (Atlanta, GA), Ohio State University (Columbus, OH), State University of New York (Stony Brook, NY), and Yale University (New Haven, CT).
RECONS page ASPENS: Astrometric Search for Planets Encircling Nearby Stars
Parallax studies such as CTIOPI have demonstrated that a 1-m class telescope equipped with a CCD camera can provide astrometric precision at the 1-2 mas level. This represents a considerable improvement over past planet-searches that were carried out with photographic plates. ASPENS joins forces with CTIOPI to take advantage of this capability within the framework of a long-timeline, volume-limited survey of the reflex motions of nearby red and white dwarf stars. This study will be able to detect companions throughout the entire brown-dwarf mass regime and possibly massive planets.
RECONS page MASSIF: Masses and Stellar Systems with Interferometry
Mass is the single most important attribute of a star. The purpose of the MASSIF Team, formed in 2000, is to measure masses of stellar and substellar objects to high precision using state-of-the-art astrometric and spectroscopic techniques, and thereby create a better understanding of the stars we see at night. Key areas of research include determining masses for the dominant members of the Galactic population, the red dwarfs, searching for the most massive and least massive stars, and improving our knowledge of the fundamental mass-luminosity relation for all stars.
RECONS page NSTARS: The Nearby Stars Project
The Nearby Stars Project (NStars) originated in 1998 and is based at Northern Arizona University in Flagstaff. Its mission is to be the most current, complete and accurate source of scientific data about all stellar objects within 25 parsecs of the Sun. At present this includes approximately 2600 stars. NStars provides research grade internet capabilities to astronomers and other scientists, support for NASA deep space missions, and basic star information to students and amateur sky observers. In addition to compiling, organizing, and presenting data for the sample members, NStars supports active research programs on nearby stars. [NStars is currently undergoing a major overhaul ... stay tuned.]

Selected Publications

  • 2006:  TSN17: Parallax Results from the CTIOPI 0.9 m Program: 20 New Members of the RECONS 10 Parsec Sample    Henry et al.
  • 2004:  TSN10: New Nearby Stars in the Southern Sky and Accurate Photometric Distance Estimates for Red Dwarfs    Henry et al.
  • 2002:  TSN06: New Southern Nearby Stars Identified by Optical Spectroscopy    Henry et al.
  • 1999:  The Optical Mass-Luminosity Relation at the End of the Main Sequence (0.08 to 0.20 Msun)    Henry et al.
  • 1997:  TSN04: Discovery of the Twentieth Nearest Star System    Henry et al.
  • 1996:  A Survey of Ca II H and K Chromospheric Emission in Southern Solar-Type Stars    Henry et al.
  • 1994:  TSN01: Standard Spectral Types (K5 to M8) for Northern Dwarfs within Eight Parsecs    Henry et al.
  • 1993:  The Mass-Luminosity Relation for Stars of Mass 1.0 to 0.08 Msun   Henry & McCarthy
  • 1991:  Plasma Discharge in N2 + CH4 at Low Pressures: Experimental Results and Applications to Titan    Thompson et al.
  • 1990:  A Systematic Search for Brown Dwarfs Orbiting Nearby Stars    Henry et al.

    • last updated 10 November 2008