ABSTRACT We present a catalog of near-infrared (NIR) spectra and associated measurements for 886 nearby M dwarfs. The spectra were obtained with the NASA-Infrared Telescope Facility SpeX Spectrograph ...during a two-year observing campaign; they have high signal-to-noise ratios (S/N > 100-150), span 0.8-2.4 m, and have Our catalog of measured values contains useful Teff and composition-sensitive features, empirical stellar parameter measurements, and kinematic, photometric, and astrometric properties compiled from the literature. We focus on measurements of M dwarf abundances (Fe/H and M/H), capitalizing on the precision of recently published empirical NIR spectroscopic calibrations. We explore systematic differences between different abundance calibrations, and from other similar M dwarf catalogs. We confirm that the M dwarf abundances we measure show the expected inverse dependence with kinematic-, activity-, and color-based age indicators. Finally, we provide updated Fe/H and M/H for 16 M dwarf planet hosts. This catalog represents the largest published compilation of NIR spectra and associated parameters for M dwarfs. It provides a rich and uniform resource for nearby M dwarfs, and will be especially valuable for measuring Habitable Zone locations and comparative abundances of the M dwarf planet hosts that will be uncovered by upcoming exoplanet surveys.
We use high dynamic range, high-resolution L-band spectroscopy to measure the radial velocity (RV) variations of the hot Jupiter in the tau Bootis planetary system. The detection of an exoplanet by ...the shift in the stellar spectrum alone provides a measure of the planet's minimum mass, with the true mass degenerate with the unknown orbital inclination. Treating the tau Boo system as a high flux ratio double-lined spectroscopic binary permits the direct measurement of the planet's true mass as well as its atmospheric properties. After removing telluric absorption and cross-correlating with a model planetary spectrum dominated by water opacity, we measure a 6sigma detection of the planet at K sub(p) = 111 + or - 5 km s super(-1), with a lsigma upper limit on the spectroscopic flux ratio of 10 super(-4). This RV leads to a planetary orbital inclination of i = (ProQuest: Formulae and/or non-USASCII text omitted) and a mass of M sub(P) = (ProQuest: Formulae and/or non-USASCII text omitted) M sub(Jup). We report the first detection of water vapor in the atmosphere of a non-transiting hot Jupiter, tau Boo b.
We describe and characterize a 25 GHz laser frequency comb based on a cavity-filtered erbium fiber mode-locked laser. The comb provides a uniform array of optical frequencies spanning 1450 nm to 1700 ...nm, and is stabilized by use of a global positioning system referenced atomic clock. This comb was deployed at the 9.2 m Hobby-Eberly telescope at the McDonald Observatory where it was used as a radial velocity calibration source for the fiber-fed Pathfinder near-infrared spectrograph. Stellar targets were observed in three echelle orders over four nights, and radial velocity precision of ∼10 m/s (∼6 MHz) was achieved from the comb-calibrated spectra.
Abstract
Recent improvements in the sensitivity and precision of the radial velocity (RV) method for exoplanets have brought it close, but not quite to, the threshold (∼10 cm s
−1
) required to ...detect Earth-mass and other potentially habitable planets around Sun-like stars. Stellar activity-driven noise in RV measurements remains a significant hurdle to achieving this goal. While various efforts have been made to disentangle this noise from real planetary signals, a greater understanding of the relationship between spectra and stellar activity is crucial to informing stellar activity mitigation. We use a partially automated method to analyze spectral lines in a set of observations of the young, active star
ϵ
Eridani from the high-precision spectrograph NEID, correlate their features (depth, FWHM, and integrated flux) with known activity indicators, and filter and curate for well-defined lines whose shape changes are sensitive to certain types of stellar activity. We then present a list of nine lines correlated with the S-index in all three line features, including four newly identified activity-sensitive lines, as well as additional lines correlated with the S-index in at least one feature, and discuss the possible implications of the behavior observed in these lines. Our line lists represent a step forward in the empirical understanding of the complex relationships between stellar activity and spectra and illustrate the importance of studying the time evolution of line morphologies with stabilized spectrographs in the overall effort to mitigate activity in the search for small, potentially Earth-like exoplanets.
ABSTRACT We target the thermal emission spectrum of the non-transiting gas giant HD 88133 b with high-resolution near-infrared spectroscopy, by treating the planet and its host star as a ...spectroscopic binary. For sufficiently deep summed flux observations of the star and planet across multiple epochs, it is possible to resolve the signal of the hot gas giant's atmosphere compared to the brighter stellar spectrum, at a level consistent with the aggregate shot noise of the full data set. To do this, we first perform a principal component analysis to remove the contribution of the Earth's atmosphere to the observed spectra. Then, we use a cross-correlation analysis to tease out the spectra of the host star and HD 88133 b to determine its orbit and identify key sources of atmospheric opacity. In total, six epochs of Keck NIRSPEC L-band observations and three epochs of Keck NIRSPEC K-band observations of the HD 88133 system were obtained. Based on an analysis of the maximum likelihood curves calculated from the multi-epoch cross-correlation of the full data set with two atmospheric models, we report the direct detection of the emission spectrum of the non-transiting exoplanet HD 88133 b and measure a radial projection of the Keplerian orbital velocity of 40 15 km s−1, a true mass of , a nearly face-on orbital inclination of , and an atmosphere opacity structure at high dispersion dominated by water vapor. This, combined with 11 years of radial velocity measurements of the system, provides the most up-to-date ephemeris for HD 88133.
Abstract
We present high-resolution observations of a flaring event in the M8 dwarf vB 10 using the near-infrared Habitable-zone Planet Finder (HPF) spectrograph on the Hobby-Eberly Telescope. The ...high stability of HPF enables us to accurately subtract a vB 10 quiescent spectrum from the flare spectrum to isolate the flare contributions and study the changes in the relative energy of the Ca
ii
infrared triplet, several Paschen lines, the He
λ
10830 triplet lines, and to select iron and magnesium lines in HPF's bandpass. Our analysis reveals the presence of a red asymmetry in the He
λ
10830 triplet, which is similar to signatures of coronal rain in the Sun. Photometry of the flare derived from an acquisition camera before spectroscopic observations and the ability to extract spectra from up-the-ramp observations with the HPF infrared detector enable us to perform time-series analysis of part of the flare and provide coarse constraints on the energy and frequency of such flares. We compare this flare with historical observations of flares around vB 10 and other ultracool M dwarfs and attempt to place limits on flare-induced atmospheric mass loss for hypothetical planets around vB 10.
Abstract
The purpose of this work is to extend a sample of accurately modeled, benchmark-grade eclipsing binaries (EBs) with accurately determined masses and radii. We select four “well-behaved” ...Kepler binaries, KIC 2306740, KIC 4076952, KIC 5193386 and KIC 5288543, each with at least eight double-lined spectra from the Apache Point Observatory Galactic Evolution Experiment instrument that is part of the Sloan Digital Sky Surveys III and IV, and from the Hobby–Eberly High Resolution Spectrograph. We obtain masses and radii with uncertainties of 2.5% or less for all four systems. Three of these systems have orbital periods longer than 9 days, and thus populate an undersampled region of the parameter space for extremely well-characterized detached EBs. We compare the derived masses and radii against
mesa mist
isochrones to determine the ages of the systems. All systems were found to be coeval, showing that the results are consistent across
mesa mist
and
phoebe
.
Using radial velocity data from the Habitable Zone Planet Finder, we have measured the mass of the Neptune-sized planet K2-25b, as well as the obliquity of its M4.5 dwarf host star in the 600-800 Myr ...Hyades cluster. This is one of the youngest planetary systems for which both of these quantities have been measured and one of the very few M dwarfs with a measured obliquity. Based on a joint analysis of the radial velocity data, time-series photometry from the K2 mission, and new transit light curves obtained with diffuser-assisted photometry, the planet's radius and mass are 3.44 0.12 R⊕ and . These properties are compatible with a rocky core enshrouded by a thin hydrogen-helium atmosphere (5% by mass). We measure an orbital eccentricity of e = 0.43 0.05. The sky-projected stellar obliquity is λ = 3° 16°, compatible with spin-orbit alignment, in contrast to other "hot Neptunes" that have been studied around older stars.
We confirm the planetary nature of TOI-1728b using a combination of ground-based photometry, near-infrared Doppler velocimetry and spectroscopy with the Habitable-zone Planet Finder. TOI-1728 is an ...old, inactive M0 star with Teff = K, which hosts a transiting super-Neptune at an orbital period of ∼3.49 days. Joint fitting of the radial velocities and TESS and ground-based transits yields a planetary radius of R⊕, mass M⊕, and eccentricity . We estimate the stellar properties, and perform a search for He 10830 absorption during the transit of this planet and claim a null detection with an upper limit of 1.1% with 90% confidence. A deeper level of He 10830 absorption has been detected in the planet atmosphere of GJ 3470b, a comparable gaseous planet. TOI-1728b is the largest super-Neptune-the intermediate subclass of planets between Neptune and the more massive gas-giant planets-discovered around an M dwarf. With its relatively large mass and radius, TOI-1728 represents a valuable data point in the M-dwarf exoplanet mass-radius diagram, bridging the gap between the lighter Neptune-sized planets and the heavier Jovian planets known to orbit M dwarfs. With a low bulk density of g cm−3, and orbiting a bright host star (J ∼ 9.6, V ∼ 12.4), TOI-1728b is also a promising candidate for transmission spectroscopy both from the ground and from space, which can be used to constrain planet formation and evolutionary models.
Abstract
Using both ground-based transit photometry and high-precision radial velocity spectroscopy, we confirm the planetary nature of TOI-3785 b. This transiting Neptune orbits an M2-Dwarf star ...with a period of ∼4.67 days, a planetary radius of 5.14 ± 0.16
R
⊕
, a mass of
14.95
−
3.92
+
4.10
M
⊕
, and a density of
ρ
=
0.61
−
0.17
+
0.18
g cm
−3
. TOI-3785 b belongs to a rare population of Neptunes (4
R
⊕
<
R
p
< 7
R
⊕
) orbiting cooler, smaller M-dwarf host stars, of which only ∼10 have been confirmed. By increasing the number of confirmed planets, TOI-3785 b offers an opportunity to compare similar planets across varying planetary and stellar parameter spaces. Moreover, with a high-transmission spectroscopy metric of ∼150 combined with a relatively cool equilibrium temperature of
T
eq
= 582 ± 16 K and an inactive host star, TOI-3785 b is one of the more promising low-density M-dwarf Neptune targets for atmospheric follow up. Future investigation into atmospheric mass-loss rates of TOI-3785 b may yield new insights into the atmospheric evolution of these low-mass gas planets around M dwarfs.
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