The Center for Astrophysics | Harvard & Smithsonian

The Center for Astrophysics | Harvard & Smithsonian

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David Latham

Center for Astrophysics

Senior Astronomer

David Latham

dlatham@cfa.harvard.edu

About

I am an observational astronomer. I have spent many nights using telescopes to study stars and to measure the masses of planets that orbit them. These days I work with space telescopes such as Kepler, K2, and TESS to measure the sizes of transiting planets. Together the masses and radii tell us a lot about the bulk properties of the planets, such as the density and whether they might have rocky surfaces where the temperature is right for water to be liquid. Our goal is to find and characterize planets enough like the Earth that we can imagine that life as we know it might be comfortable there.

Projects

CfA Redshift Catalog

Optical and Infrared Astronomy

The universe is expanding, carrying galaxies with it like flotsam on a fast-flowing river. This expansion also stretches the wavelength of light, which astronomers call cosmological redshift, since it pushes visible light colors toward the red end of the spectrum. That means astronomers can determine the distance to far-away galaxies by measuring the redshift of light they produce. The CfA Redshift Catalog (ZCAT), created by researchers at the Center for Astrophysics | Harvard & Smithsonian, is a clearinghouse for historical redshift data from a number of observatories, including the 1.5-Meter Tillinghast Telescope and the MMT Observatory, both CfA-operated telescopes located at the Fred Lawrence Whipple Observatory (FLWO) in Arizona. This data provides a map of galaxies in three dimensions, allowing astronomers to piece together how galaxies group on the largest scales in the universe. ZCAT is an essential resource for data on redshift surveys up to 2008, carrying on the legacy of the original CfA Redshift Surveys conducted in the 1970s and ‘80s.

Telescopes and Instruments

High Accuracy Radial Velocity Planet Searcher-North (HARPS-N)

Measuring the mass of a distant exoplanet requires tracking the changes in light of the host star as the planet’s gravity tugs it slightly — a delicate process. The High Accuracy Radial velocity Planet Searcher for the Northern hemisphere (HARPS-N) is an instrument designed for that purpose. HARPS-N is installed on the Telescopio Nazionale Galileo at the Roque de los Muchachos Observatory on the island of La Palma in the Canary Islands. The instrument provides valuable follow-up observations for the smaller exoplanets identified by NASA’s Kepler/K2 space telescope and other observatories. Astronomers at the Center for Astrophysics | Harvard & Smithsonian are part of the international collaboration operating the instrument. Using the high quality data from HARPS-N, astronomers hope to measure the masses of Earth-like worlds to sufficient accuracy to determine how much these planets resemble ours.

Visit the HARPS-N Website

MMT Observatory

The MMT Observatory is the premier visible-light and infrared telescope jointly managed by the Smithsonian Astrophysical Observatory, part of the Center for Astrophysics | Harvard & Smithsonian, and the University of Arizona. Located at the Fred Lawrence Whipple Observatory (FLWO) in southern Arizona, this 6.5-meter (21 foot) telescope is used to study objects across the field of astronomy, from the Solar System to distant galaxies. The MMT has provided a testbed for new telescope technologies developed by scientists and engineers at the CfA and the University of Arizona.

Visit the MMT Website

Transiting Exoplanet Survey Satellite (TESS)

Astronomers have discovered thousands of planets orbiting other stars. Extrapolating from that knowledge, the Milky Way alone is probably home to hundreds of billions of planets, many of which are likely rocky, Earth-like worlds. NASA’s Transiting Exoplanet Survey Satellite (TESS) is a space observatory designed to look for exoplanets in orbit around 200,000 nearby bright stars, with a particular interest in identifying small planets. Astronomers from the Center for Astrophysics | Harvard & Smithsonian are part of the scientific team to analyze TESS data, as well as performing follow-up observations. The relative closeness of worlds in the TESS survey will allow astronomers to even study some of their atmospheres, using the future Giant Magellan Telescope (GMT) and other observatories. TESS observational program is complementary to NASA’s long-running Kepler/K2 mission, and could identify as many as 20,000 new exoplanet orbiting a wide variety of star types.

Visit the TESS Website

Hungarian-made Automated Telescope Network (HATNet)

The Hungarian-made Automated Telescope Network (HATNet) is a set of computer-controlled small telescopes located at various observatories around the world. Five of these telescopes are hosted at the Fred Lawrence Whipple Observatory (FLWO), a Center for Astrophysics | Harvard & Smithsonian facility in southern Arizona. HATNet is designed to look for planets in orbit around bright stars; since beginning operations in 2001, astronomers have used the network to identify 70 confirmed exoplanets and several hundred additional candidates that have not yet been confirmed as exoplanets or ruled out as false positives.

Visit the HATNet Website

Kepler/K2

Since the early 1990s, astronomers have identified thousands of planets orbiting other stars. Most of those identifications have come thanks to one observatory: NASA’s Kepler space telescope. Until it lost its ability to point, Kepler observed a region of the sky containing about 150,000 stars with potential planets, monitoring them for the slight decrease in light caused by planets crossing in front of the star. After the spacecraft’s pointing control failed, the mission was renamed K2, and it continued to hunt for exoplanets as it tumbled slowly, with its field of view drifting slowly across the sky. The mission finally ended in 2018, though the data it produced continues to provide astronomers with valuable information about planets in our galactic neighborhood. Astronomers from the Center for Astrophysics | Harvard & Smithsonian were responsible for the preparation of the catalog for potentially interesting stars, and have participated extensively in follow-up observations of Kepler planetary discoveries.

Visit the Kepler/K2 Website

Magellan Telescopes

The twin Magellan Telescopes in Chile are each 6.5 meter optical telescopes. These telescopes are both equipped with instruments to take images and spectra of light from a wide variety of astronomical sources, including exoplanet systems, star-forming regions, supernova remnants, and interacting galaxies. The Magellan Telescopes — named Baade and Clay — are hosted at the Las Campanas Observatory and are operated by a consortium of institutions, including the Center for Astrophysics | Harvard & Smithsonian, Carnegie Institution for Science, University of Arizona, the University of Michigan, and the Massachusetts Institute of Technology. In addition, CfA scientists and engineers provided a wide field f/5 focal system (including secondary mirror and corrective optics), and a powerful astronomical camera for use at the Clay telescope.

Visit the Magellan Telescopes Website

MEarth

How many Earth-sized planets are out there? How many of those might support life? Answering these questions is complicated because Earth-like worlds are small, making them hard to detect. The MEarth Project — pronounced “mirth” — simplifies the problem by looking for planets orbiting small, red M dwarf stars. Potentially habitable Earth-sized planets have smaller orbits around these stars than yellow Sun-like stars, allowing MEarth to identify them. The MEarth telescopes are operated by the Center for Astrophysics | Harvard & Smithsonian and located at the CfA’s Fred Lawrence Whipple Observatory (FLWO) in Arizona and the Cerro Tololo Inter-American Observatory (CTIO) in Chile. Astronomers have used MEarth to identify multiple planets, including the rocky planet GJ1132b.

Visit the MEarth Website