Browsing by Author "Dong, Jiayin"

Now showing 1 - 4 of 4
  • Thumbnail Image
    Item
    Gaia-4b and 5b: Radial Velocity Confirmation of Gaia Astrometric Orbital Solutions Reveal a Massive Planet and a Brown Dwarf Orbiting Low-mass Stars
    (IOP Publishing Ltd, 2025) Stefansson, Gudmundur; Mahadevan, Suvrath; Winn, Joshua N.; Marcussen, Marcus L.; Kanodia, Shubham; Albrecht, Simon; Fitzmaurice, Evan; Mikulskyte, One; Canas, Caleb I.; Espinoza Retamal, Juan Ignacio; Zwart, Yiri; Krolikowski, Daniel M.; Hotnisky, Andrew; Robertson, Paul; Alvarado-Montes, Jaime A.; Bender, Chad F.; Blake, Cullen H.; Callingham, J. R.; Cochran, William D.; Delamer, Megan; Diddams, Scott A.; Dong, Jiayin; Fernandes, Rachel B.; Giovinazzi, Mark R.; Halverson, Samuel; Libby-Roberts, Jessica; Logsdon, Sarah E.; Mcelwain, Michael W.; Ninan, Joe P.; Rajagopal, Jayadev; Reji, Varghese; Roy, Arpita; Schwab, Christian; Wright, Jason T.
    Gaia astrometry of nearby stars is precise enough to detect the tiny displacements induced by substellar companions, but radial velocity (RV) data are needed for definitive confirmation. Here we present RV follow-up observations of 28 M and K stars with candidate astrometric substellar companions, which led to the confirmation of two systems, Gaia-4b and Gaia-5b, identification of five systems that are single lined but require additional data to confirm as substellar companions, and the refutation of 21 systems as stellar binaries. Gaia-4b is a massive planet (M = 11.8 +/- 0.7 MJ) in a P = 571.3 +/- 1.4 day orbit with a projected semimajor axis a0 = 0.312 +/- 0.040 mas orbiting a 0.644 +/- 0.02M circle dot star. Gaia-5b is a brown dwarf (M = 20.9 +/- 0.5MJ) in a P = 358.62 +/- 0.20 days eccentric e = 0.6423 +/- 0.0026 orbit with a projected angular semimajor axis of a0 = 0.947 +/- 0.038 mas around a 0.34 +/- 0.03M circle dot star. Gaia-4b is one of the first exoplanets discovered via the astrometric technique, and is one of the most massive planets known to orbit a low-mass star.
  • No Thumbnail Available
    Item
    NEID Reveals That the Young Warm Neptune TOI-2076 b Has a Low Obliquity
    (2023) Frazier, Robert C.; Stefansson, Gudmundur; Mahadevan, Suvrath; Yee, Samuel W.; Canas, Caleb I.; Winn, Joshua N.; Luhn, Jacob; Dai, Fei; Doyle, Lauren; Cegla, Heather; Kanodia, Shubham; Robertson, Paul; Wisniewski, John; Bender, Chad F.; Dong, Jiayin; Gupta, Arvind F.; Halverson, Samuel; Hawley, Suzanne; Hebb, Leslie; Holcomb, Rae; Kowalski, Adam; Libby-Roberts, Jessica; Lin, Andrea S. J.; McElwain, Michael W.; Ninan, Joe P.; Petrovich, Cristobal; Roy, Arpita; Schwab, Christian; Terrien, Ryan C.; Wright, Jason T.
    TOI-2076 b is a sub-Neptune-sized planet (R = 2.39 + 0.10 R-circle plus) that transits a young (204 + 50 MYr) bright (V= 9.2) K-dwarf hosting a system of three transiting planets. Using spectroscopic observations obtained with the NEID spectrograph on the WIYN 3.5 m Telescope, we model the Rossiter-McLaughlin effect of TOI-2076 b, and derive a sky-projected obliquity of lambda = - 3 (-15) (+16) . Using the size of the star (R = 0.775 + 0.015 R-?), and the stellar 16 rotation period (P-rot = 7.27 + 0.23 days), we estimate an obliquity of y =18(-9) (+10) (psi < 34 degrees at 95% confidence), 10 demonstrating that TOI-2076 b is in a well-aligned orbit. Simultaneous diffuser-assisted photometry from the 3.5 m telescope at Apache Point Observatory rules out flares during the transit. TOI-2076 b joins a small but growing sample of young planets in compact multi-planet systems with well-aligned orbits, and is the fourth planet with an age ?300 Myr in a multi-transiting system with an obliquity measurement. The low obliquity of TOI-2076 b and the presence of transit timing variations in the system suggest the TOI-2076 system likely formed via convergent disk migration in an initially well-aligned disk.
  • No Thumbnail Available
    Item
    Precise Transit and Radial-velocity Characterization of a Resonant Pair: The Warm Jupiter TOI-216c and Eccentric Warm Neptune TOI-216b
    (2021) Dawson, Rebekah I.; Huang, Chelsea X.; Brahm, Rafael; Collins, Karen A.; Hobson, Melissa J.; Jordan, Andres; Dong, Jiayin; Korth, Judith; Trifonov, Trifon; Abe, Lyu; Agabi, Abdelkrim; Bruni, Ivan; Butler, R. Paul; Barbieri, Mauro; Collins, Kevin I.; Conti, Dennis M.; Crane, Jeffrey D.; Crouzet, Nicolas; Dransfield, Georgina; Evans, Phil; Espinoza, Nestor; Gan, Tianjun; Guillot, Tristan; Henning, Thomas; Lissauer, Jack J.; Jensen, Eric L. N.; Sainte, Wenceslas Marie; Mekarnia, Djamel; Myers, Gordon; Nandakumar, Sangeetha; Relles, Howard M.; Sarkis, Paula; Torres, Pascal; Shectman, Stephen; Schmider, Francois-Xavier; Shporer, Avi; Stockdale, Chris; Teske, Johanna; Triaud, Amaury H. M. J.; Wang, Sharon Xuesong; Ziegler, Carl; Ricker, G.; Vanderspek, R.; Latham, David W.; Seager, S.; Winn, J.; Jenkins, Jon M.; Bouma, L. G.; Burt, Jennifer A.; Charbonneau, David; Levine, Alan M.; McDermott, Scott; McLean, Brian; Rose, Mark E.; Vanderburg, Andrew; Wohler, Bill
    TOI-216 hosts a pair of warm, large exoplanets discovered by the TESS mission. These planets were found to be in or near the 2:1 resonance, and both of them exhibit transit timing variations (TTVs). Precise characterization of the planets' masses and radii, orbital properties, and resonant behavior can test theories for the origins of planets orbiting close to their stars. Previous characterization of the system using the first six sectors of TESS data suffered from a degeneracy between planet mass and orbital eccentricity. Radial-velocity measurements using HARPS, FEROS, and the Planet Finder Spectrograph break that degeneracy, and an expanded TTV baseline from TESS and an ongoing ground-based transit observing campaign increase the precision of the mass and eccentricity measurements. We determine that TOI-216c is a warm Jupiter, TOI-216b is an eccentric warm Neptune, and that they librate in 2:1 resonance with a moderate libration amplitude of deg, a small but significant free eccentricity of for TOI-216b, and a small but significant mutual inclination of 12-39 (95% confidence interval). The libration amplitude, free eccentricity, and mutual inclination imply a disturbance of TOI-216b before or after resonance capture, perhaps by an undetected third planet.
  • No Thumbnail Available
    Item
    The Warm Neptune GJ 3470b Has a Polar Orbit
    (2022) Stefansson, Gudmundur; Mahadevan, Suvrath; Petrovich, Cristobal; Winn, Joshua N.; Kanodia, Shubham; Millholland, Sarah C.; Maney, Marissa; Canas, Caleb, I; Wisniewski, John; Robertson, Paul; Ninan, Joe P.; Ford, Eric B.; Bender, Chad F.; Blake, Cullen H.; Cegla, Heather; Cochran, William D.; Diddams, Scott A.; Dong, Jiayin; Endl, Michael; Fredrick, Connor; Halverson, Samuel; Hearty, Fred; Hebb, Leslie; Hirano, Teruyuki; Lin, Andrea S. J.; Logsdon, Sarah E.; Lubar, Emily; McElwain, Michael W.; Metcalf, Andrew J.; Monson, Andrew; Rajagopal, Jayadev; Ramsey, Lawrence W.; Roy, Arpita; Schwab, Christian; Schweiker, Heidi; Terrien, Ryan C.; Wright, Jason T.
    The warm Neptune GJ 3470b transits a nearby (d = 29 pc) bright slowly rotating M1.5-dwarf star. Using spectroscopic observations during two transits with the newly commissioned NEID spectrometer on the WIYN 3.5 m Telescope at Kitt Peak Observatory, we model the classical Rossiter-McLaughlin effect, yielding a sky-projected obliquity of lambda = 98(-12)(+15)degrees and a v sin i = 0.85(-033)(+0.27) km s(-1). Leveraging information about the rotation period and size of the host star, our analysis yields a true obliquity of psi = 95(-8)(+9)degrees, revealing that GJ 3470b is on a polar orbit. Using radial velocities from HIRES, HARPS, and the Habitable-zone Planet Finder, we show that the data are compatible with a long-term radial velocity (RV) slope of gamma = -0.0022 +/- 0.0011 m s(-1) day(-1) over a baseline of 12.9 yr. If the RV slope is due to acceleration from another companion in the system, we show that such a companion is capable of explaining the polar and mildly eccentric orbit of GJ 3470b using two different secular excitation models. The existence of an outer companion can be further constrained with additional RV observations, Gaia astrometry, and future high-contrast imaging observations. Lastly, we show that tidal heating from GJ 3470b's mild eccentricity has most likely inflated the radius of GJ 3470b by a factor of similar to 1.5-1.7, which could help account for its evaporating atmosphere.