نتائج البحث - "Terrien, Ryan"

1

تقرير

The death of Vulcan: NEID reveals the planet candidate orbiting HD 26965 is stellar activity

المصدر: AJ 167 243 (2024)

مصطلحات موضوعية: Astrophysics - Earth and Planetary Astrophysics, Astrophysics - Instrumentation and Methods for Astrophysics, Astrophysics - Solar and Stellar Astrophysics

الوصف: We revisit the long-studied radial velocity (RV) target HD26965 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 identified as a planet candidate is most likely an activity-induced signal. Correlating the bulk (spectrally-averaged) RV with canonical line activity indicators confirms a multi-day 'lag' between the observed activity indicator time series and the measured RV. When accounting for this lag, we show that much of the observed RV signal can be removed by a linear detrending of the data. Investigating activity at the line-by-line level, we find a depth-dependent correlation between individual line RVs and the bulk RVs, further indicative of periodic suppression of convective blueshift causing the observed RV variability, rather than an orbiting planet. We conclude that the combined evidence of the activity correlations and depth dependence is consistent with a radial velocity signature dominated by a rotationally-modulated activity signal at a period of $\sim$42 days. We hypothesize that this activity signature is due to a combination of spots and convective blueshift suppression. The tools applied in our analysis are broadly applicable to other stars, and could help paint a more comprehensive picture of the manifestations of stellar activity in future Doppler RV surveys.
Comment: 25 pages, 13 figures. Accepted in AJ

URL الوصول: http://arxiv.org/abs/2404.17494

2

تقرير

The Epoch of Giant Planet Migration Planet Search Program. II. A Young Hot Jupiter Candidate around the AB Dor Member HS Psc

المؤلفون: Tran, Quang H., Bowler, Brendan P., Cochran, William D., Halverson, Samuel, Mahadevan, Suvrath, Ninan, Joe P., Robertson, Paul, Stefánsson, Guðmundur, Terrien, Ryan C.

مصطلحات موضوعية: Astrophysics - Earth and Planetary Astrophysics

الوصف: We report the discovery of a hot Jupiter candidate orbiting HS Psc, a K7 ($\approx$0.7 $M_\odot$) member of the $\approx$130 Myr AB Doradus moving group. Using radial velocities over 4 years from the Habitable-zone Planet Finder spectrograph at the Hobby-Eberly Telescope, we find a periodic signal at $P_b = 3.986_{-0.003}^{+0.044}$ d. A joint Keplerian and Gaussian process stellar activity model fit to the RVs yields a minimum mass of $m_p \sin i = 1.5_{-0.4}^{+0.6}$ $M_\mathrm{Jup}$. The stellar rotation period is well constrained by the Transiting Exoplanet Survey Satellite light curve ($P_\mathrm{rot} = 1.086 \pm 0.003$ d) and is not an integer harmonic nor alias of the orbital period, supporting the planetary nature of the observed periodicity. HS Psc b joins a small population of young, close-in giant giant planet candidates with robust age and mass constraints and demonstrates that giant planets can either migrate to their close-in orbital separations by 130 Myr or form $in \; situ$. Given its membership in a young moving group, HS Psc represents an excellent target for follow-up observations to further characterize this young hot Jupiter, refine its orbital properties, and search for additional planets in the system.
Comment: Accepted for publication to The Astronomical Journal, 27 pages, 6 figures

URL الوصول: http://arxiv.org/abs/2403.02378

3

تقرير

Revisiting $\epsilon$ Eridani with NEID: Identifying New Activity-Sensitive Lines in a Young K Dwarf Star

المؤلفون: Jiang, Sarah, Roy, Arpita, Halverson, Samuel, Bender, Chad F., Selgas, Carlos, Otor, O. Justin, Mahadevan, Suvrath, Stefánsson, Guðmundur, Terrien, Ryan C., Schwab, Christian

المصدر: The Astronomical Journal (2023), 167, 9

مصطلحات موضوعية: Astrophysics - Earth and Planetary Astrophysics, Astrophysics - Solar and Stellar Astrophysics

الوصف: 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 ($\sim$10 cm/s) 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 $\epsilon$ Eridani from the high-precision spectrograph NEID, correlate their features (depth, full width at half maximum, and integrated flux) with known activity indicators, and filter and curate for well-behaved lines whose shape changes are sensitive to certain types of stellar activity. We then present a list of 9 lines correlated with the S-index in all three line features, including 4 newly-identified activity-sensitive lines; as well as additional lines correlated with 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.
Comment: 16 pages, 9 figures. For associated data cube, see https://doi.org/10.5281/zenodo.10085919

URL الوصول: http://arxiv.org/abs/2311.10677

4

تقرير

TOI-5344 b: A Saturn-like planet orbiting a super-Solar metallicity M0 dwarf

المصدر: AJ 167 4 (2024)

مصطلحات موضوعية: Astrophysics - Earth and Planetary Astrophysics, Astrophysics - Solar and Stellar Astrophysics

الوصف: 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 0.6m telescope), radial velocity (the Habitable-zone Planet Finder), and speckle imaging (the NN-Explore Exoplanet Stellar Speckle Imager). TOI-5344 b is a Saturn-like giant planet ($\rho = 0.80^{+0.17}_{-0.15}\ \text{g cm}^{-3}$) with a planetary radius of $9.7 \pm \ 0.5 \ \text{R}_{\oplus}$ ($0.87 \pm \ 0.04 \ \text{R}_{\text{Jup}}$) and a planetary mass of $135^{+17}_{-18} \text{M}_{\oplus}$ ($0.42^{+0.05}_{-0.06} \ \text{M}_{\text{Jup}}$). It has an orbital period of $3.792622 \pm 0.000010$ days and an orbital eccentricity of $0.06^{+0.07}_{-0.04}$. We measure a high metallicity for TOI-5344 of [Fe/H] = $0.48 \pm 0.12$, where the high metallicity is consistent with expectations from formation through core accretion. We compare the metallicity of the M-dwarf hosts of giant exoplanets to that of M-dwarf hosts of non-giants ($\lesssim 8\ \text{R}_{\oplus}$). While the two populations appear to show different metallicity distributions, quantitative tests are prohibited by various sample caveats.
Comment: 19 pages, 10 figures, 4 tables, AJ accepted. Added references

URL الوصول: http://arxiv.org/abs/2310.20634

5

تقرير

TOI-2015b: A Warm Neptune with Transit Timing Variations Orbiting an Active mid M Dwarf

مصطلحات موضوعية: Astrophysics - Earth and Planetary Astrophysics

الوصف: We report the discovery of a close-in ($P_{\mathrm{orb}} = 3.349\:\mathrm{days}$) warm Neptune with clear transit timing variations (TTVs) orbiting the nearby ($d=47.3\:\mathrm{pc}$) active M4 star, TOI-2015. We characterize the planet's properties using TESS photometry, precise near-infrared radial velocities (RV) with the Habitable-zone Planet Finder (HP) Spectrograph, ground-based photometry, and high-contrast imaging. A joint photometry and RV fit yields a radius $R_p~=~3.37_{-0.20}^{+0.15} \:\mathrm{R_\oplus}$, mass $m_p~=~16.4_{-4.1}^{+4.1}\:\mathrm{M_\oplus}$, and density $\rho_p~=~2.32_{-0.37}^{+0.38} \:\mathrm{g cm^{-3}}$ for TOI-2015b, suggesting a likely volatile-rich planet. The young, active host star has a rotation period of $P_{\mathrm{rot}}~=~8.7 \pm~0.9~\mathrm{days}$ and associated rotation-based age estimate of $1.1~\pm~0.1\:\mathrm{Gyr}$. Though no other transiting planets are seen in the TESS data, the system shows clear TTVs of super period $P_{\mathrm{sup}}~\approx~430\:\mathrm{days}$ and amplitude $\sim$$100\:\mathrm{minutes}$. After considering multiple likely period ratio models, we show an outer planet candidate near a 2:1 resonance can explain the observed TTVs while offering a dynamically stable solution. However, other possible two-planet solutions -- including 3:2 and 4:3 resonance -- cannot be conclusively excluded without further observations. Assuming a 2:1 resonance in the joint TTV-RV modeling suggests a mass of $m_b~=~13.3_{-4.5}^{+4.7}\:\mathrm{M_\oplus}$ for TOI-2015b and $m_c~=~6.8_{-2.3}^{+3.5}\:\mathrm{M_\oplus}$ for the outer candidate. Additional transit and RV observations will be beneficial to explicitly identify the resonance and further characterize the properties of the system.
Comment: 29 pages, 15 figures, 6 tables. Accepted for publication in The Astronomical Journal

URL الوصول: http://arxiv.org/abs/2310.11775

6

تقرير

The Extreme Stellar-Signals Project III. Combining Solar Data from HARPS, HARPS-N, EXPRES, and NEID

المؤلفون: Zhao, Lily L., Dumusque, Xavier, Ford, Eric B., Llama, Joe, Mortier, Annelies, Bedell, Megan, Moulla, Khaled Al, Bender, Chad F., Blake, Cullen H., Brewer, John M., Cameron, Andrew Collier, Cosentino, Rosario, Figueira, Pedro, Fischer, Debra A., Ghedina, Adriano, Gonzalez, Manuel, Halverson, Samuel, Kanodia, Shubham, Latham, David W., Lin, Andrea S. J., Curto, Gaspare Lo, Lodi, Marcello, Logsdon, Sarah E., Lovis, Christophe, Mahadevan, Suvrath, Monson, Andrew, Ninan, Joe P., Pepe, Francesco, Roettenbacher, Rachael M., Roy, Arpita, Santos, Nuno C., Schwab, Christian, Stefánsson, Guðmundur, Szymkowiak, Andrew E., Terrien, Ryan C., Udry, Stephane, Weiss, Sam A., Wildi, François, Wildi, Thibault, Wright, Jason T.

مصطلحات موضوعية: Astrophysics - Earth and Planetary Astrophysics, Astrophysics - Instrumentation and Methods for Astrophysics, Astrophysics - Solar and Stellar Astrophysics

الوصف: We present an analysis of Sun-as-a-star observations from four different high-resolution, stabilized spectrographs -- HARPS, HARPS-N, EXPRES, and NEID. With simultaneous observations of the Sun from four different instruments, we are able to gain insight into the radial velocity precision and accuracy delivered by each of these instruments and isolate instrumental systematics that differ from true astrophysical signals. With solar observations, we can completely characterize the expected Doppler shift contributed by orbiting Solar System bodies and remove them. This results in a data set with measured velocity variations that purely trace flows on the solar surface. Direct comparisons of the radial velocities measured by each instrument show remarkable agreement with residual intra-day scatter of only 15-30 cm/s. This shows that current ultra-stabilized instruments have broken through to a new level of measurement precision that reveals stellar variability with high fidelity and detail. We end by discussing how radial velocities from different instruments can be combined to provide powerful leverage for testing techniques to mitigate stellar signals.
Comment: 17 pages, 9 figures, accepted for publication

URL الوصول: http://arxiv.org/abs/2309.03762

7

تقرير

Stable fiber-illumination for extremely precise radial velocities with NEID

مصطلحات موضوعية: Astrophysics - Instrumentation and Methods for Astrophysics, Astrophysics - Earth and Planetary Astrophysics

الوصف: NEID is a high-resolution red-optical precision radial velocity (RV) spectrograph recently commissioned at the WIYN 3.5 m telescope at Kitt Peak National Observatory, Arizona, USA. NEID has an extremely stable environmental control system, and spans a wavelength range of 380 to 930 nm with two observing modes: a High Resolution (HR) mode at R $\sim$ 112,000 for maximum RV precision, and a High Efficiency (HE) mode at R $\sim$ 72,000 for faint targets. In this manuscript we present a detailed description of the components of NEID's optical fiber feed, which include the instrument, exposure meter, calibration system, and telescope fibers. Many parts of the optical fiber feed can lead to uncalibratable RV errors, which cannot be corrected for using a stable wavelength reference source. We show how these errors directly cascade down to performance requirements on the fiber feed and the scrambling system. We detail the design, assembly, and testing of each component. Designed and built from the bottom-up with a single-visit instrument precision requirement of 27 $\textrm{cm~s}^{-1}$, close attention was paid to the error contribution from each NEID subsystem. Finally, we include the lab and on-sky tests performed during instrument commissioning to test the illumination stability, and discuss the path to achieving the instrumental stability required to search for a true Earth twin around a Solar-type star.
Comment: The Astronomical Journal, Volume 166, Number 3, 2023

URL الوصول: http://arxiv.org/abs/2307.12403

8

تقرير

TOI-1859b: A 64-Day Warm Jupiter on an Eccentric and Misaligned Orbit

مصطلحات موضوعية: Astrophysics - Earth and Planetary Astrophysics

الوصف: Warm Jupiters are close-in giant planets with relatively large planet-star separations (i.e., $10< a/R_\star <100$). Given their weak tidal interactions with their host stars, measurements of stellar obliquity may be used to probe the initial obliquity distribution and dynamical history for close-in gas giants. Using spectroscopic observations, we confirm the planetary nature of TOI-1859b and determine the stellar obliquity of TOI-1859 to be $\lambda = 38.9^{+2.8}_{-2.7}\deg$ relative to its planetary companion using the Rossiter-McLaughlin effect. TOI-1859b is a 64-day warm Jupiter orbiting around a late-F dwarf and has an orbital eccentricity of $0.57^{+0.12}_{-0.16}$, inferred purely from transit light curves. The eccentric and misaligned orbit of TOI-1859b is likely an outcome of dynamical interactions, such as planet-planet scattering and planet-disk resonance crossing.
Comment: 15 pages, 7 figures, 1 table; accepted to ApJL

URL الوصول: http://arxiv.org/abs/2305.16495

9

تقرير

Stellar Characterization and Radius Inflation of Hyades M Dwarf Stars From the APOGEE Survey

مصطلحات موضوعية: Astrophysics - Solar and Stellar Astrophysics, Astrophysics - Astrophysics of Galaxies

الوصف: We present a spectroscopic analysis of a sample of 48 M dwarf stars ($0.2 M_{\odot}< M < 0.6 M_{\odot}$) from the Hyades open cluster using high-resolution H-band spectra from the SDSS/APOGEE survey. Our methodology adopts spectrum synthesis with LTE MARCS model atmospheres, along with the APOGEE DR17 line list, to determine effective temperatures, surface gravities, metallicities, and projected rotational velocities. The median metallicity obtained for the Hyades M dwarfs is [M/H]= 0.09$\pm$0.03 dex, indicating a small internal uncertainty and good agreement with optical results for Hyades red-giants. Overall, the median radii are larger than predicted by stellar models by 1.6$\pm$2.3\% and 2.4$\pm$2.3\%, relative to a MIST and DARTMOUTH isochrone, respectively. We emphasize, however, that these isochrones are different and the fractional radius inflation for the fully- and partially-convective regimes have distinct behaviors depending on the isochrone. Using a MIST isochrone there is no evidence of radius inflation for the fully convective stars, while for the partially convective M-dwarfs the radii are inflated by 2.7$\pm$2.1\%, which is in agreement with predictions from models that include magnetic fields. For the partially-convective stars, rapid-rotators present on average higher inflation levels than slow-rotators. The comparison with SPOTS isochrone models indicates that the derived M dwarf radii can be explained by accounting for stellar spots in the photosphere of the stars, with 76\% of the studied M dwarfs having up to 20\% spot coverage, and the most inflated stars with $\sim$20 -- 40\% spot coverage.
Comment: Accepted for publication by The Astrophysical Journal (ApJ)

URL الوصول: http://arxiv.org/abs/2305.07065

10

تقرير

TOI-5375 B: A Very Low Mass Star at the Hydrogen-Burning Limit Orbiting an Early M-type Star

المؤلفون: Lambert, Mika, Bender, Chad F., Kanodia, Shubham, Cañas, Caleb I., Monson, Andrew, Stefánsson, Guðmundur, Cochran, William D., Everett, Mark E., Gupta, Arvind F., Hearty, Fred, Kobulnicky, Henry A., Libby-Roberts, Jessica E., Lin, Andrea S. J., Mahadevan, Suvrath, Ninan, Joe P., Parker, Brock A., Robertson, Paul, Schwab, Christian, Terrien, Ryan C.

مصطلحات موضوعية: Astrophysics - Solar and Stellar Astrophysics, Astrophysics - Earth and Planetary Astrophysics

الوصف: The TESS mission detected a companion orbiting TIC 71268730, categorized it as a planet candidate, and designated the system TOI-5375. Our follow-up analysis using radial velocity data from the Habitable-zone Planet Finder (HPF), photometric data from Red Buttes Observatory (RBO), and speckle imaging with NN-EXPLORE Exoplanet Stellar Speckle Imager (NESSI) determined that the companion is a very low mass star (VLMS) near the hydrogen-burning mass limit with a mass of 0.080$\pm{0.002} M_{\Sun}$ ($83.81\pm{2.10} M_{J}$), a radius of 0.1114$^{+0.0048}_{-0.0050} R_{\Sun}$ (1.0841$^{0.0467}_{0.0487} R_{J}$), and brightness temperature of $2600\pm{70}$ K. This object orbits with a period of 1.721553$\pm{0.000001}$ days around an early M dwarf star ($0.62\pm{0.016}M_{\Sun}$). TESS photometry shows regular variations in the host star's TESS light curve, which we interpreted as activity-induced variation of $\sim$2\%, and used this variability to measure the host star's stellar rotation period of 1.9716$^{+0.0080}_{-0.0083}$ days. The TOI-5375 system provides tight constraints on stellar models of low-mass stars at the hydrogen-burning limit and adds to the population in this important region.
Comment: 15 pages, 8 figures, Accepted to the Astronomical Journal

URL الوصول: http://arxiv.org/abs/2303.16193

تنقيح النتائج