Monday, May 21, 2012
Cahill, Hameetman Auditorium
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.