As the second full day of the American Astronomical Society (AAS) meeting comes to an end, exoplanets yet again were a major focus. The first press conference of the day included announcements of surprising planetary systems. First, we learned of evidence of a planetary system in the Hyades star cluster. This cluster is just 150 light-years from Earth and provides a laboratory to study stellar evolution. Ben Zuckerman of UCLA and colleagues used the HIRES instrument on the Keck Telescope to observe the elemental characteristics of 10 white dwarfs in the Hyades star cluster. (A white dwarf is the remnant core of a Sun-like star.) One of those targets shows a strong signature of calcium, which is an element a white dwarf shouldn’t contain unless it shredded a rocky body — such as an asteroid — and pulled in the material.
The first planets discovered outside our solar system were found orbiting a compact stellar remnant called a neutron star. // photo by NASA/JPL-Caltech/R. Hurt (SSC)
Aleksander Wolszczan of Pennsylvania State University then described observations and the current understanding of planetary systems around compact neutron stars. Wolszczan has been involved in the search for exoplanets for a long time — he discovered the first confirmed extrasolar planets. He closed the press conference with a statement that echoes throughout this meeting: Planets are everywhere.
I also attended a few science sessions about characterizing exoplanet atmospheres. One interesting talk in particular was from Laura Kreidberg, a graduate student at the University of Chicago. She and her advisor (Jacob Bean) are using the near-infrared Wide Field Camera 3 on the Hubble Space Telescope to analyze the light from GJ 1214b. They’re trying to determine if this super-Earth’s atmosphere is completely water vapor or something else. So far, they’ve completed data collection from four out of 15 orbits and expect to have all their data by July. When asked what their next observational target will be, Kreidberg quickly stated 55 Cancri e, which is another nearby super-Earth.
On Tuesday evening, I attended a town hall presentation (and lively discussion) about the Wide-Field InfraRed Survey Telescope (WFIRST) and whether to use one of the telescopes recently donated to NASA by the National Reconnaissance Office (NRO). WFIRST is the top priority space mission for the next decade, as described by Astro2010: The Astronomy and Astrophysics Decadal Survey. This project will incorporate a large infrared survey, dark energy research, and direct imaging of exoplanets (clearly, this research topic is everywhere).
Astro2010: The Astronomy and Astrophysics Decadal Survey listed the Wide-Field InfraRed Survey Telescope (WFIRST) as the top priority space mission in the next decade. Scientists have re-evaluated its design; shown here is a previous possible layout. Now, astronomers are exploring the option of use one of the 2.4-meter telescopes donated by National Reconnaissance Office in 2012. // photo by NASA
Astronomers had begun thinking of telescope assembly ideas for the observatory, but the NRO scopes provide another option: a 2.4-meter mirror, which is about twice the size of the WFIRST proposals originally considered. During Tuesday night’s town hall meeting, the co-chairs of the project’s Science Definition Team (Neil Gehrels of NASA and David Spergel of Princeton) described the basic capabilities of WFIRST and compared the previous structure options to the 2.4-meter one. This telescope would image down to 27th magnitude over thousands of square degrees.
Roughly a dozen scientists presented different research topics that WFIRST would investigate and what type of results they expect from the larger aperture instrument. These included mapping dwarf galaxies near the Andromeda Galaxy (M31), exoplanet searches using microlensing, observing thousands of galaxy clusters across cosmic time (to learn about dark energy’s effects), and ways to block a star’s light while trying to image its worlds. “We’ll be looking at a wealth of information when surveying the skies,” says Spergel. And given the excitement from each of the presenters, it’s clear that many in that room agreed.
Not all, however, think that launching WFIRST (with the 2.4-meter NRO telescope body) will be feasible. To study infrared radiation, the instruments must be cooled to very low temperatures. This is because infrared radiation traces heat, and scientists need to ensure that the telescope’s heat doesn’t effect observations. Thus, the observatory would have to carry a large (and heavy) cooling system.
The Science Definition Team is currently evaluating both the positives and negatives of adapting one of the 2.4-meter NRO telescopes for WFIRST. They will report this information to NASA — along with a cost estimate — at the end of April.
Tuesday was certainly an interesting day at AAS, and I’m looking forward to another information-packed day on Wednesday.
Check out my Monday recap here.