Abstract
The Habitable-zone Planet Finder (HPF) is a fiber-fed precise radial velocity (RV) spectrograph at the 10 m Hobby–Eberly Telescope (HET). Due to its fixed-altitude design, the HET pupil ...changes appreciably across a track, leading to significant changes of the fiber far-field illumination. HPF’s fiber scrambler is designed to suppress the impact of these illumination changes on the RVs—but the residual impact on the RV measurements has yet to be probed on-sky. We use GJ 411, a bright early type (M2) M dwarf to probe the effects of far-field input trends due to these pupil variations on HPF RVs. These large changes (∼2x) in the pupil area and centroid present a harsh test of HPF’s far-field scrambling. Our results show that the RVs are effectively decoupled from these extreme far-field input changes due to pupil centroid offsets, attesting to the effectiveness of the scrambler design. This experiment allows us to test the impact of these changes with large pupil variation on-sky, something we would not easily be able to do at a conventional optical telescope. While the pupil and illumination changes expected at these other telescopes are small, scaling from our results enables us to estimate and bound these effects, and show that they are controllable even for the new and next generation of RV instruments in their quest to beat down instrumental noise sources toward the goal of a few
cm
s
−
1
.
Solar contamination, due to moonlight and atmospheric scattering of sunlight, can cause systematic errors in stellar radial velocity (RV) measurements that significantly detract from the ∼10 cm s−1 ...sensitivity required for the detection and characterization of terrestrial exoplanets in or near habitable zones of Sun-like stars. The addition of low-level spectral contamination at variable effective velocity offsets introduces systematic noise when measuring velocities using classical mask-based or template-based cross-correlation techniques. Here we present simulations estimating the range of RV measurement error induced by uncorrected scattered sunlight contamination. We explore potential correction techniques, using both simultaneous spectrometer sky fibers and broadband imaging via coherent fiber imaging bundles, that could reliably reduce this source of error to below the photon-noise limit of typical stellar observations. We discuss the limitations of these simulations, the underlying assumptions, and mitigation mechanisms. We also present and discuss the components designed and built into the NEID (NN-EXPLORE Exoplanet Investigations with Doppler spectroscopy) precision RV instrument for the WIYN 3.5 m telescope, to serve as an ongoing resource for the community to explore and evaluate correction techniques. We emphasize that while "bright time" has been traditionally adequate for RV science, the goal of 10 cm s−1 precision on the most interesting exoplanetary systems may necessitate access to darker skies for these next-generation instruments.
Abstract
The coherent low-frequency radio emission detected by LOFAR from Gliese 1151, a quiescent M4.5 dwarf star, has radio emission properties consistent with theoretical expectations of ...star–planet interactions for an Earth-sized planet on a 1- to 5-day orbit. New near-infrared radial velocities from the Habitable-zone Planet Finder (HPF) spectrometer on the 10 m Hobby–Eberly Telescope at McDonald Observatory, combined with previous velocities from HARPS-N, reveal a periodic Doppler signature consistent with an
m
sin
i
=
2.5
±
0.5
M
⊕
exoplanet on a 2.02-day orbit. Precise photometry from the Transiting Exoplanet Survey Satellite (TESS) shows no flares or activity signature, consistent with a quiescent M dwarf. While no planetary transit is detected in the TESS data, a weak photometric modulation is detectable in the photometry at a ∼2-day period. This independent detection of a candidate planet signal with the Doppler radial velocity technique adds further weight to the claim of the first detection of star–exoplanet interactions at radio wavelengths and helps validate this emerging technique for the detection of exoplanets.
We report on the validation of two planets orbiting the nearby (36 pc) M2 dwarf TOI-1266 observed by the TESS mission. This system is one of a few M dwarf multiplanet systems with close-in planets ...where the inner planet is substantially larger than the outer planet. The inner planet is sub-Neptune-sized (R = 2.46 0.08 R⊕) with an orbital period of 10.9 days, while the outer planet has a radius of R⊕ and resides in the exoplanet radius valley-the transition region between rocky and gaseous planets. With an orbital period of 18.8 days, the outer planet receives an insolation flux of 2.4 times that of Earth, similar to the insolation of Venus. Using precision near-infrared radial velocities with the Habitable-zone Planet Finder Spectrograph, we place upper mass limits of 15.9 and 6.4 M⊕ at 95% confidence for the inner and outer planet, respectively. A more precise mass constraint of both planets, achievable with current radial velocity instruments given the host star brightness (V = 12.9, J = 9.7), will yield further insights into the dominant processes sculpting the exoplanet radius valley.
The Kepler mission has provided a treasure trove of eclipsing binaries (EBs), observed at extremely high photometric precision, nearly continuously for several years. We are carrying out a survey of ...∼100 of these EBs to derive dynamical masses and radii with precisions of 3% or better. We use multiplexed near-infrared H-band spectroscopy from the Sloan Digital Sky Survey-III and -IV APOGEE instrument and optical spectroscopy from the Hobby-Eberly Telescope High-resolution Spectrograph to derive double-lined spectroscopic orbits and dynamical mass ratios (q) for the EB sample, two of which we showcase in this paper. This orbital information is combined with Kepler photometry to derive orbital inclination, dynamical masses of the system components, radii, and temperatures. These measurements are directly applicable for benchmarking stellar models that are integrating the next generation of improvements, such as the magnetic suppression of convection efficiency, updated opacity tables, and fine-tuned equations of state. We selected our EB sample to include systems with low-mass ( ) primary or secondary components, as well as many EBs expected to populate the relatively sparse parameter space below ∼0.5 M . In this paper, we describe our EB sample and the analytical techniques we are utilizing, and also present masses and radii for two systems that inhabit particularly underpopulated regions of mass-radius-period space: KIC 2445134 and KIC 3003991. Our joint spectroscopic and photometric analysis of KIC 2445134 ( ) yields masses and radii of , , , , and a temperature ratio of our analysis of KIC 3003991 ( ) yields , , , , and a temperature ratio of .
Abstract
We validate the planetary nature of an ultra-short-period planet orbiting the M dwarf KOI-4777. We use a combination of space-based photometry from Kepler, high-precision, near-infrared ...Doppler spectroscopy from the Habitable-zone Planet Finder, and adaptive optics imaging to characterize this system. KOI-4777.01 is a Mars-sized exoplanet (
R
p
= 0.51 ± 0.03
R
⊕
) orbiting the host star every 0.412 days (∼9.9 hr). This is the smallest validated ultra-short period planet known and we see no evidence for additional massive companions using our HPF RVs. We constrain the upper 3
σ
mass to
M
p
< 0.34
M
⊕
by assuming the planet is less dense than iron. Obtaining a mass measurement for KOI-4777.01 is beyond current instrumental capabilities.
Binary stars make up a significant portion of all stellar systems. Consequently, an understanding of the bulk properties of binary stars is necessary for a full picture of star formation. Binary ...surveys indicate that both multiplicity fraction and typical orbital separation increase as functions of primary mass. Correlations with higher-order architectural parameters such as mass ratio are less well constrained. We seek to identify and characterize double-lined spectroscopic binaries (SB2s) among the 1350 M-dwarf ancillary science targets with APOGEE spectra in the SDSS-III Data Release 13. We measure the degree of asymmetry in the APOGEE pipeline cross-correlation functions (CCFs) and use those metrics to identify a sample of 44 high-likelihood candidate SB2s. At least 11 of these SB2s are known, having been previously identified by Deshpande et al. and/or El-Badry et al. We are able to extract radial velocities (RVs) for the components of 36 of these systems from their CCFs. With these RVs, we measure mass ratios for 29 SB2s and five SB3s. We use Bayesian techniques to fit maximum-likelihood (but still preliminary) orbits for four SB2s with eight or more distinct APOGEE observations. The observed (but incomplete) mass-ratio distribution of this sample rises quickly toward unity. Two-sided Kolmogorov-Smirnov tests find probabilities of 18.3% and 18.7%, demonstrating that the mass-ratio distribution of our sample is consistent with those measured by Pourbaix et al. and Fernandez et al., respectively.
We report observations of a possible young transiting planet orbiting a previously known weak-lined T-Tauri star in the 7-10 Myr old Orion-OB1a/25-Ori region. The candidate was found as part of the ...Palomar Transient Factory (PTF) Orion project. It has a photometric transit period of 0.448413 + or - 0.000040 days, and appears in both 2009 and 2010 PTF data. Follow-up low-precision radial velocity (RV) observations and adaptive optics imaging suggest that the star is not an eclipsing binary, and that it is unlikely that a background source is blended with the target and mimicking the observed transit. RV observations with the Hobby-Eberly and Keck telescopes yield an RV that has the same period as the photometric event, but is offset in phase from the transit center by approx = - 0.22 periods. The amplitude (half range) of the RV variations is 2.4 km s super(-1) and is comparable with the expected RV amplitude that stellar spots could induce. The RV curve is likely dominated by stellar spot modulation and provides an upper limit to the projected companion mass of M sub(p) sin i sub(orb) <, ~4.8 + or - 1.2 M sub(Jup); when combined with the orbital inclination, i sub(orb), of the candidate planet from modeling of the transit light curve, we find an upper limit on the mass of the planetary candidate of M sub(p) <, ~5.5 + or - 1.4 M sub(Jup). This limit implies that the planet is orbiting close to, if not inside, its Roche limiting orbital radius, so that it may be undergoing active mass loss and evaporation.
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