NEAR-INFRARED CALIBRATION SOURCES FOR HIGH-PRECISION RADIAL VELOCITY MEASUREMENTS AND THE SEARCH FOR LIFE OUTSIDE OUR SOLAR SYSTEM

 

Stephen L. Redman, Gillian Nave, and Craig J. Sansonetti

 

An Earth-mass planet in the habitable zone around a solar-type star imparts a 0.08 m s-1 radial velocity in the stellar spectrum with a period of 365 days.  Such a radial velocity signal is undetectable on current optical astrophysical spectrometers, primarily because of the magnitude of the radial velocity signal.  In comparison, an Earth-mass planet in the habitable zone around a low-mass star (such as an M dwarf) would impart a 1 or 2 m s-1 radial velocity signal in the stellar spectrum.  Such a signal would be readily measurable, except that these stars give off most of their light in the near-infrared (1 micrometer - 5 micrometers), and there is currently a dearth of calibration sources for this spectral region. 

Here at NIST, we have been working with astrophysicists around the world to develop and measure new calibration sources for this spectral region.  These calibration sources include atomic emission lamps (such as uranium-neon), molecular NIST Standard Reference Material (SRM) absorption cells, fiber fabry perots (FFPs), and laser frequency combs (LFCs).  We anticipate that these calibration sources will be utilized on the next generation of near-infrared astrophysical spectrographs, including Calar Alto high-Resolution search for M dwarfs with Exoearths with Near-infrared and optical Échelle Spectrographs (CARMENES), the Habitable-zone Planet Finder (HPF), and SpectroPolarimetre InfraROUge (SPIRou).