Monday, May 21, 2012
Astronomy Tea Talk
Detecting Small Planets Orbiting Small Stars Using Small Telescopes and GPS
Cullen Blake, Princeton
The majority of stars in the solar neighborhood are low-mass M dwarfs. However, these small stars have largely been excluded from the ongoing Doppler surveys that so far have identified hundreds of extrasolar planets. Low-mass stars are attractive targets for planet searches, and present a potential shortcut to the detection of rocky, Earth-like planets orbiting their hosts in the so-called Habitable Zone. The current best precision for Doppler measurements at optical wavelengths is 1 m/s, but comparable precision has not yet been demonstrated in the near infrared (NIR), where low-mass stars are brightest. I will present a new take on an old technique for making Doppler measurements in the NIR. This method relies on absorption features in Earth's atmosphere (telluric lines) as a "zero velocity" reference. I will show how data from a Global Positioning System (GPS) receiver can be used to generate precise synthetic telluric absorption templates, which are crucial for NIR Doppler measurements. I will describe results from Doppler observations of low-mass stars using NIRSPEC on Keck as well as an ongoing survey of 1,000 M stars using the APOGEE instrument as part of SDSS-3. Finally, I will outline future plans to use a network of small telescopes coupled to a NIR spectrometer to carry out a census of companions down to a few Earth masses orbiting the 50 closest low mass stars to the Sun.