The Crires Search for Planets Around the Lowest-Mass Stars. I. High-Precision Near-Infrared Radial Velocities With an Ammonia Gas Cell

Bean, Jacob L.; Seifahrt, Andreas; Hartman, Henrik; Nilsson, Hampus; Wiedemann, G.; Reiners, A.; Dreizler, S.; Henry, Todd J.

doi:10.1088/0004-637x/713/1/410

Cited by 164 publications

(159 citation statements)

References 52 publications

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“…In addition, Mahadevan & Ge (2009) reported on a mixture that produces a dense absorption spectrum in the H band. Bean et al (2010) reported that for their CRIRES survey consisting of a search for planets around M-dwarfs, they reach a RV precision of 5 m s −1 using a NH 3 gas cell in the K band. A similar strategy for wavelength calibration is the use of telluric lines in the NIR as a natural gas cell.…”

Section: Instrumental Limitationsmentioning

confidence: 99%

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Detecting planets around very cool dwarfs at near infrared wavelengths with the radial velocity technique

Rodler

Burgo

Witte

et al. 2011

A&A

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Context. Radial velocity monitoring of very cool dwarfs such as late M-and hot L-dwarfs has become a promising tool in the search for rocky planets as well as follow-up planetary candidates around dwarfs detected by transit surveys. These stars are faint at optical wavelengths, as their spectral flux distribution peaks at near-infrared (NIR) wavelengths. For this reason, it is desirable to measure the radial velocities in this wavelength regime. However, in the NIR very few medium-and high-resolution spectrographs are available at large telescopes. In the near future, high-resolution spectrographs for the NIR will be built, which will allow us to search for rocky planets around cool M-dwarfs and L-dwarfs from radial velocities monitoring. Aims. We investigate the precision that can be attained in radial velocity measurements of very cool dwarfs in the NIR. The goal is to determine in which atmospheric window of the Earth's atmosphere the highest radial velocity precision can be achieved to help in designing the next generation of NIR high-resolution spectrographs. Methods. We use stellar atmosphere synthetic models for an M-and an L-dwarf with temperatures of 2200 K and 1800 K, respectively, and a theoretical spectrum of the Earth's transmission in the spectral range from 0.9 to 2.5 μm. We simulate a series of Doppler-shifted spectra observed with different resolving powers and signal-to-noise ratios, and for different rotational broadenings of the dwarf. For different combinations of the input parameters, we recover the radial velocity by means of cross-correlation with a high signal-to-noise ratio template and determine the associate uncertainties. Results. The highest precision in radial velocity measurements for the cool M-dwarf is found in the Y band around 1.0 μm, while for the L-dwarf it is determined in the J band around 1.25 μm. We note that synthetic models may lack some faint absorption features or underestimate their abundances. In addition, some instrumental/calibration aspects that are not taken into account in our estimations would increase the uncertainties.

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Section: Instrumental Limitationsmentioning

confidence: 99%

“…Usually, the PSF of the spectrograph is close to a Gaussian function, but it can be slightly asymmetric (e.g. Endl et al 2000;Bean et al 2010). In our simulations, we adopted a Gaussian function as the PSF of the spectrograph.…”

Section: Creating the Data Setsmentioning

confidence: 99%

Detecting planets around very cool dwarfs at near infrared wavelengths with the radial velocity technique

Rodler

Burgo

Witte

et al. 2011

A&A

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“…As an example, iodine gas cells, which have been used extensively as wavelength calibrators in optical RV surveys, do not offer a sufficient density of absorption lines in the NIR domain. For this reason, most existing NIR RV studies have used telluric lines to achieve wavelength calibration (Blake et al 2010;Crockett et al 2011;Bailey et al 2012;Tanner et al 2012;Davison et al 2015), with the exception of Bean et al (2010), who used an ammonia gas cell with CRyogenic high-resolution InfraRed Echelle Spectrograph (CRIRES) at the VLT to obtain unprecedented long-term precisions of ≈5-10 m s −1 in the NIR on targets with K S -band magnitudes between 4.4 and 8.0.…”

Section: Introductionmentioning

confidence: 99%

A High-Precision Near-Infrared Survey for Radial Velocity Variable Low-Mass Stars Using Cshell and a Methane Gas Cell

Gagné

Plavchan

Gao

et al. 2016

ApJ

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233

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We present the results of a precise near-infrared (NIR) radial velocity (RV) survey of 32 low-mass stars with spectral types K2-M4 using CSHELL at the NASA InfraRed Telescope Facility in the K band with an isotopologue methane gas cell to achieve wavelength calibration and a novel, iterative RV extraction method. We surveyed 14 members of young (≈25-150 Myr) moving groups, the young field star εEridani, and 18 nearby (<25 pc) low-mass stars and achieved typical single-measurement precisions of 8-15 m s −1 with a long-term stability of 15-50 m s −1 over longer baselines. We obtain the best NIR RV constraints to date on 27 targets in our sample, 19 of which were never followed by high-precision RV surveys. Our results indicate that very active stars can display long-term RV variations as low as ∼25-50 m s −1 at ≈2.3125 μm, thus constraining the effect of jitter at these wavelengths. We provide the first multiwavelength confirmation of GJ876bc and independently retrieve orbital parameters consistent with previous studies. We recovered RV variabilities for HD160934AB and GJ725AB that are consistent with their known binary orbits, and nine other targets are candidate RV variables with a statistical significance of 3σ-5σ. Our method, combined with the new iSHELL spectrograph, will yield long-term RV precisions of 5 m s −1 in the NIR, which will allow the detection of super-Earths near the habitable zone of mid-M dwarfs.

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“…Planets with masses between 1 and 10 M Earth , ''super-Earths,'' have indeed been detected in the last few years around low-mass stars, such as Gl 581 d and Gl 667C c by radial velocity (Udry et al, 2007;Mayor et al, 2009;Vogt et al, 2010;Bonfils et al, 2011;Forveille et al, 2011;AngladaEscudé et al, 2012;Delfosse et al, 2012) and GJ 1214 b by transit (Charbonneau et al, 2009;Sada et al, 2010;Carter et al, 2011;Kundurthy et al, 2011). Several observational campaigns designed specifically to detect planets around low-mass stars are now underway (Nutzman and Charbonneau, 2008;Boss et al, 2009;Zechmeister et al, 2009;Bean et al, 2010;Rodler et al, 2011).…”

Section: Introductionmentioning

confidence: 99%

Tidal Venuses: Triggering a Climate Catastrophe via Tidal Heating

et al. 2013

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Traditionally, stellar radiation has been the only heat source considered capable of determining global climate on long timescales. Here, we show that terrestrial exoplanets orbiting low-mass stars may be tidally heated at highenough levels to induce a runaway greenhouse for a long-enough duration for all the hydrogen to escape. Without hydrogen, the planet no longer has water and cannot support life. We call these planets ''Tidal Venuses'' and the phenomenon a ''tidal greenhouse.'' Tidal effects also circularize the orbit, which decreases tidal heating. Hence, some planets may form with large eccentricity, with its accompanying large tidal heating, and lose their water, but eventually settle into nearly circular orbits (i.e., with negligible tidal heating) in the habitable zone (HZ). However, these planets are not habitable, as past tidal heating desiccated them, and hence should not be ranked highly for detailed follow-up observations aimed at detecting biosignatures. We simulated the evolution of hypothetical planetary systems in a quasi-continuous parameter distribution and found that we could constrain the history of the system by statistical arguments. Planets orbiting stars with masses < 0.3 M Sun may be in danger of desiccation via tidal heating. We have applied these concepts to Gl 667C c, a *4.5 M Earth planet orbiting a 0.3 M Sun star at 0.12 AU. We found that it probably did not lose its water via tidal heating, as orbital stability is unlikely for the high eccentricities required for the tidal greenhouse. As the inner edge of the HZ is defined by the onset of a runaway or moist greenhouse powered by radiation, our results represent a fundamental revision to the HZ for noncircular orbits. In the appendices we review (a) the moist and runaway greenhouses, (b) hydrogen escape, (c) stellar mass-radius and mass-luminosity relations, (d) terrestrial planet mass-radius relations, and (e) linear tidal theories.

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The Crires Search for Planets Around the Lowest-Mass Stars. I. High-Precision Near-Infrared Radial Velocities With an Ammonia Gas Cell

Cited by 164 publications

References 52 publications

Detecting planets around very cool dwarfs at near infrared wavelengths with the radial velocity technique

Detecting planets around very cool dwarfs at near infrared wavelengths with the radial velocity technique

A High-Precision Near-Infrared Survey for Radial Velocity Variable Low-Mass Stars Using Cshell and a Methane Gas Cell

Tidal Venuses: Triggering a Climate Catastrophe via Tidal Heating

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