Astronomy & Telescopes

Sub-milli-Kelvin Instruments – Radial Velocity Measurements: Tests with the Habitable-zone Planet Finder

By Keith Cowing
Press Release
October 20, 2016
Filed under
Sub-milli-Kelvin Instruments – Radial Velocity Measurements: Tests with the Habitable-zone Planet Finder

Insufficient instrument thermo-mechanical stability is one of the many roadblocks for achieving 10cm/s Doppler radial velocity (RV) precision, the precision needed to detect Earth-twins orbiting Solar-type stars.

Highly temperature and pressure stabilized spectrographs allow us to better calibrate out instrumental drifts, thereby helping in distinguishing instrumental noise from astrophysical stellar signals. We present the design and performance of the Environmental Control System (ECS) for the Habitable-zone Planet Finder (HPF), a high-resolution (R=50,000) fiber-fed near infrared (NIR) spectrograph for the 10m Hobby Eberly Telescope at McDonald Observatory. HPF will operate at 180K, driven by the choice of an H2RG NIR detector array with a 1.7micron cutoff. This ECS has demonstrated 0.6mK RMS stability over 15 days at both 180K and 300K, and maintained high quality vacuum (<10βˆ’7Torr) over months, during long-term stability tests conducted without a planned passive thermal enclosure surrounding the vacuum chamber. This control scheme is versatile and can be applied as a blueprint to stabilize future NIR and optical high precision Doppler instruments over a wide temperature range from ~77K to elevated room temperatures. A similar ECS is being implemented to stabilize NEID, the NASA/NSF NN-EXPLORE spectrograph for the 3.5m WIYN telescope at Kitt Peak, operating at 300K. A full SolidWorks 3D-CAD model and a comprehensive parts list of the HPF ECS are included with this manuscript to facilitate the adaptation of this versatile environmental control scheme in the broader astronomical community. A Versatile Technique to Enable sub-milli-Kelvin Instrument Stability for Precise Radial Velocity Measurements: Tests with the Habitable-zone Planet Finder Gudmundur Stefansson, Frederick Hearty, Paul Robertson, Suvrath Mahadevan, Tyler Anderson, Eric Levi, Chad Bender, Matthew Nelson, Andrew Monson, Basil Blank, Samuel Halverson, Chuck Henderson, Lawrence Ramsey, Arpita Roy, Christian Schwab, Ryan Terrien
(Submitted on 19 Oct 2016)

Comments: Accepted for publication in ApJ. 16 pages, 10 figures. For a publicly available SolidWorks model of the HPF ECS, see this https URL
Subjects: Instrumentation and Methods for Astrophysics (astro-ph.IM); Earth and Planetary Astrophysics (astro-ph.EP)
Cite as: arXiv:1610.06216 [astro-ph.IM] (or arXiv:1610.06216v1 [astro-ph.IM] for this version)
Submission history
From: Gudmundur Stefansson
[v1] Wed, 19 Oct 2016 20:59:41 GMT (11416kb,D)

Explorers Club Fellow, ex-NASA Space Station Payload manager/space biologist, Away Teams, Journalist, Lapsed climber, Synaesthete, Na’Vi-Jedi-Freman-Buddhist-mix, ASL, Devon Island and Everest Base Camp veteran, (he/him) πŸ––πŸ»