Vacuum Extreme Radial Velocity Experiment (VERVE)

The VERVE spectrograph, which is stand-alone and observatory ready.

Overview

Precision radial velocity continues to be a key exoplanet detection method. The need to complete the census of neighborhood stars down to Earth masses, along with follow-up of planetary candidates from NASA transit missions such as Kepler and TESS, increases the need for ultra-precise Doppler technology. Ground-based precision radial velocity measurements support science objectives for: 1) target identification, 2) follow-up validation and characterization, and 3) mass and orbit determination. These NASA missions include Kepler, TESS, JWST, WFIRST, and future HABEX/ LUVOIR missions.

Our approach involves the development and fusion of two technologies: 1) externally dispersed spectrographs and 2) compact adaptive optics systems. The development of these two technologies are closely tied together. We have developed technology capable of achieving 10 cm/s Doppler precision on nearby bright stars, for the purpose of detecting and characterizing terrestrial-mass planets. This instrument is called Vacuum Extreme Radial Velocity Experiment or VERVE. The instrument hardware has been designed, developed, assembled, aligned and tested, and is ready for deployment to an observatory. However, this is a single-mode optical fiber fed instrument. To efficiently couple light into this instrument, the light that is injected needs to be diffraction limited.

Thus the motivation for the second part of this development activity - the development of a compact adaptive optics unit to provide such a diffraction limited image. To do this, we strongly leverage off the work done on the Keck fiber injection unit. This narrowly-focused compact AO system/fiber injection unit will improve coupling efficiency into the single mode fiber and open up opportunities for use on many undersubscribed, ground-based telescopes of modest aperture size (1.5 to 4 meter).

Publications

Attaining Doppler Precision of 10 cm s-1 with a Lock-in Amplified Spectrometer
Rebecca Jensen-Clem, Philip S. Muirhead, Michael Bottom, J. Kent Wallace, Gautam Vasisht, and John Asher Johnson
Publications of the Astronomical Society of the Pacific, vol. 127, 1105 (2015)

Ultra-Precise Radial Velocimetry with Lock-In Amplified Externally Dispersed Interferometry
Rebecca Jensen-Clem, Philip S. Muirhead, Gautam Vasisht, J. Kent Wallace, and John Asher Johnson
American Astronomical Society, AAS Meeting 221, id.149.10 (2013)