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Precise Radial Velocities of Cool Low Mass Stars With iSHELL
- Publication Year :
- 2019
- Publisher :
- arXiv, 2019.
-
Abstract
- The coolest dwarf stars are intrinsically faint at visible wavelengths and exhibit rotationally modulated stellar activity from spots and plages. It is advantageous to observe these stars at near infrared (NIR) wavelengths (1-2.5 microns) where they emit the bulk of their bolometric luminosity and are most quiescent. In this work we describe our methodology and results in obtaining precise radial velocity (RV) measurements of low mass stars using K-band spectra taken with the R~80,000 iSHELL spectrograph and the NASA Infrared Telescope Facility (IRTF) using a methane isotopologue gas cell in the calibration unit. Our novel analysis pipeline extracts RVs by minimizing the RMS of the residuals between the observed spectrum and a forward model. The model accounts for the gas cell, tellurics, blaze function, multiple sources of quasi-sinusoidal fringing, and line spread function of the spectrograph (LSF). The stellar template is derived iteratively using the target observations themselves through averaging barycenter-shifted residuals. We have demonstrated 5 ms^-1 precision over one year timescales for the M4 dwarf Barnard's Star and K dwarf 61 Cygni A, and 3 ms^-1 over a month for the M2 dwarf GJ 15 A. This work demonstrates the potential for iSHELL to determine dynamical masses for candidate exoplanets discovered with the NASA TESS mission, and to search for exoplanets orbiting moderately active and/or young K and M dwarfs.<br />Comment: Accepted for publication in ApJ (2019) 46 pages 31 Figures
- Subjects :
- Physics
Earth and Planetary Astrophysics (astro-ph.EP)
Astrophysics::Instrumentation and Methods for Astrophysics
FOS: Physical sciences
Astronomy and Astrophysics
Astrophysics
Astrophysics::Cosmology and Extragalactic Astrophysics
7. Clean energy
01 natural sciences
010305 fluids & plasmas
Stars
Astrophysics - Solar and Stellar Astrophysics
Space and Planetary Science
0103 physical sciences
Astrophysics::Solar and Stellar Astrophysics
Astrophysics::Earth and Planetary Astrophysics
Low Mass
Astrophysics - Instrumentation and Methods for Astrophysics
010303 astronomy & astrophysics
Instrumentation and Methods for Astrophysics (astro-ph.IM)
Astrophysics::Galaxy Astrophysics
Solar and Stellar Astrophysics (astro-ph.SR)
Astrophysics - Earth and Planetary Astrophysics
Subjects
Details
- Database :
- OpenAIRE
- Accession number :
- edsair.doi.dedup.....d4c778b5b3816caced0e605ecc900a63
- Full Text :
- https://doi.org/10.48550/arxiv.1908.07560