57 hasil untuk "Samuel Halverson"
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Artikel Jurnal
Exposure-averaged Gaussian Processes for Combining Overlapping Datasets
Physically motivated Gaussian process (GP) kernels for stellar variability, like the commonly used damped, driven simple harmonic oscillators that model stellar granulation and p -mode oscillations, quantify the instantaneous covariance between any two points. For kernels whose timescales are…
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Artikel Jurnal
Revisiting ϵ Eridani with NEID: Identifying New Activity-sensitive Lines in a Young K Dwarf Star
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…
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Artikel Jurnal
The Epoch of Giant Planet Migration Planet Search Program. II. A Young Hot Jupiter Candidate around the AB Dor Member HS Psc
We report the discovery of a hot Jupiter candidate orbiting HS Psc, a K7 (≈0.7 M _⊙ ) member of the ≈130 Myr AB Doradus moving group. Using radial velocities over 4 yr from the Habitable-zone Planet Finder spectrograph at the Hobby–Eberly Telescope, we find a periodic signal of…
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Artikel Jurnal
The Epoch of Giant Planet Migration Planet Search Program. III. The Occurrence Rate of Young Giant Planets inside the Water Ice Line
We present statistical results from the Epoch of Giant Planet Migration RV planet search program. This survey was designed to measure the occurrence rate of giant planets interior to the water ice line of young Sun-like stars, compare this to the prevalence of giant planets at older ages, and…
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Artikel Jurnal
An Obliquity Measurement of the Hot Neptune TOI-1694b
We present spectral observations of the multiplanet host TOI-1694 during the transit of TOI-1694b, a 26.1 M _⊕ hot Neptune with a 3.77 day orbit. By analyzing radial velocities obtained from the Keck Planet Finder, we modeled the Rossiter–McLaughlin effect and constrained the sky-projected…
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Artikel Jurnal
The OATMEAL Survey. II. The 3D Spin–Orbit Obliquity of an Eccentric Transiting Brown Dwarf in the Ruprecht 147 Open Cluster
We present a new analysis of the CWW 89 system as part of the Orbital Architectures of Transiting Massive Exoplanets And Low-mass stars (OATMEAL) survey. The CWW 89 system is a member of the 2.8 Gyr old Ruprecht 147 (NGC 6774) cluster and consists of two stars, CWW 89A (EPIC 219388192) and CWW 89B…
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Artikel Jurnal
Origins of Super Jupiters: TOI-2145b has a Moderately Eccentric and Nearly Aligned Orbit
Super Jupiters are giant planets with several Jupiter masses. It remains an open question whether these planets originate with such high masses or grow through collisions. Previous work demonstrates that warm super Jupiters tend to have more eccentric orbits compared to regular-mass warm Jupiters…
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Artikel Jurnal
Quiet Please: Detrending Radial Velocity Variations from Stellar Activity with a Physically Motivated Spot Model
For solar-type stars, spots and their associated magnetic regions induce radial velocity perturbations through the Doppler rotation signal and the suppression of convective blueshift, collectively known as rotation modulation. We developed the Rotation–Convection (RC) model: a method of detrending…
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Artikel Jurnal
Searching for GEMS: Discovery and Characterization of Two Brown Dwarfs Around M Dwarfs
Brown dwarfs bridge the gap between stars and planets, providing valuable insight into both planetary and stellar-formation mechanisms. Yet the census of transiting brown-dwarf companions, in particular around M-dwarf stars, remains incomplete. We report the discovery of two transiting brown dwarfs…
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Artikel Jurnal
The Death of Vulcan: NEID Reveals That the Planet Candidate Orbiting HD 26965 Is Stellar Activity
We revisit the long-studied radial velocity (RV) target HD 26965 using recent observations from the NASA-NSF “NEID” precision Doppler facility. Leveraging a suite of classical activity indicators, combined with line-by-line RV analyses, we demonstrate that the claimed 45-day signal previously…
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Artikel Jurnal
A Revised Mass and Period for the Habitable Zone super-Earth GJ 3378 b: A Planet Straddling the Cosmic Shoreline
The nearby ( d = 7.7 pc) M4V star GJ 3378 is a target of our radial velocity (RV) exoplanet survey of fully convective stars in the solar neighborhood with the near-IR Habitable-zone Planet Finder (HPF) spectrometer on the Hobby–Eberly Telescope (HET) at McDonald Observatory. Recently, C. Moutou et…
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Artikel Jurnal
Confirmation of the Low-eccentricity Warm Jupiter HD 278555 b with NEID
The study of warm Jupiters is crucial to understanding the processes that govern giant-planet formation and migration. These planets sit at the boundary between cold giant planets and hot Jupiters, and studying their orbital properties, including period, eccentricity, and spin–orbit alignment, can…
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Artikel Jurnal
TOI-5344 b: A Saturn-like Planet Orbiting a Super-solar Metallicity M0 Dwarf
We confirm the planetary nature of TOI-5344 b as a transiting giant exoplanet around an M0-dwarf star. TOI-5344 b was discovered with the Transiting Exoplanet Survey Satellite photometry and confirmed with ground-based photometry (the Red Buttes Observatory 0.6 m telescope), radial velocity (the…
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Artikel Jurnal
Searching for GEMS: Two Super-Jupiters Around M Dwarfs that May have Formed via Gravitational Instability
We present the discovery of TOI-6303b and TOI-6330b, two massive transiting super-Jupiters orbiting a M0 and a M2 dwarf star, respectively, as part of the Searching for Giant Exoplanets around M-dwarf Stars (GEMS) survey. These were detected by NASA’s Transiting Exoplanet Survey Satellite and then…
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Artikel Jurnal
Searching for GEMS: TOI-7149 b, an Inflated Giant Planet Causing a 12% Transit of a Fully Convective M-dwarf
We describe the discovery and characterization of TOI-7149 b, a 0.705 ± 0.075 M _J , 1.18 ± 0.045 R _J gas giant on a ∼2.65 days period orbit transiting an M4V star with a mass of 0.344 ± 0.030 M _⊙ and an effective temperature of 3363 ± 59 K. The planet was first discovered using NASA’s TESS…
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Artikel Jurnal
Searching for GEMS: TOI-5916 b & TOI-6158 b are Two Saturn-density Planets Orbiting M2 Dwarfs
We confirm the planetary nature of (1) TOI-5916 b and (2) TOI-6158 b, two giant exoplanets around M-dwarf stars (GEMS), both discovered by the Transiting Exoplanet Survey Satellite. Both systems were confirmed with ground-based photometry (Red Buttes Observatory and Swope, respectively) and radial…
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Artikel Jurnal
The NEID Earth Twin Survey. IV. Confirming an 89 days, Planet Orbiting a Nearby Sun-like Star
We present the confirmation of HD 190360 d, a warm ( $P=88.69{0}_{-0.049}^{+0.051}\,\mathrm{days}$ ), low-mass ( $m\sin i=10.2{3}_{-0.80}^{+0.81}\,{M}_{\oplus }$ ) planet orbiting the nearby ( d = 16.0 pc), Sun-like (G7) star HD 190360. We detect HD 190360 d at high statistical significance even…
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Artikel Jurnal
TOI-1670 c, a 40 day Orbital Period Warm Jupiter in a Compact System, Is Well Aligned
We report the measurement of the sky-projected obliquity angle λ of the warm Jovian exoplanet TOI-1670 c via the Rossiter–McLaughlin effect. We observed the transit window during UT 2023 April 20 for 7 continuous hours with NEID on the 3.5 m WIYN Telescope at Kitt Peak National Observatory…
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Artikel Jurnal
The NEID Earth Twin Survey. I. Confirmation of a 31 Day Planet Orbiting HD 86728
With close to 3 yr of observations in hand, the NEID Earth Twin Survey (NETS) is starting to unearth new astrophysical signals for a curated sample of bright, radial velocity (RV)-quiet stars. We present the discovery of the first NETS exoplanet, HD 86728b, a ${m}_{p}\sin i={9.16}_{-0.56}^{+0.55}\…
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Artikel Jurnal
The NEID Earth Twin Survey. III. Survey Performance after Three Years on Sky
The NEID Earth Twin Survey (NETS) has been delivering a rich set of precise radial velocity (RV) measurements for 41 bright, nearby main-sequence stars. Here, we describe the status of the survey after 3 yr on sky, and we present the full set of RV measurements and accompanying stellar activity…