Browsing by Author "Adibekyan, Vardan"

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    TESS spots a mini- interior to a hot saturn in the TOI-2000 system
    (2023) Sha, Lizhou; Vanderburg, Andrew M.; Huang, Chelsea X.; Armstrong, David J.; Brahm, Rafael; Giacalone, Steven; Wood, Mackenna L.; Collins, Karen A.; Nielsen, Louise D.; Hobson, Melissa J.; Ziegler, Carl; Howell, Steve B.; Torres-Miranda, Pascal; Mann, Andrew W.; Zhou, George; Delgado-Mena, Elisa; Rojas, Felipe, I; Abe, Lyu; Trifonov, Trifon; Adibekyan, Vardan; Sousa, Sergio G.; Fajardo-Acosta, Sergio B.; Guillot, Tristan; Howard, Saburo; Littlefield, Colin; Hawthorn, Faith; Schmider, Francois-Xavier; Eberhardt, Jan; Tan, Thiam-Guan; Osborn, Ares; Schwarz, Richard P.; Strom, Paul; Jordan, Andres; Wang, Gavin; Henning, Thomas; Massey, Bob; Law, Nicholas; Stockdale, Chris; Furlan, Elise; Srdoc, Gregor; Wheatley, Peter J.; Navascues, David Barrado; Lissauer, Jack J.; Stassun, Keivan G.; Ricker, George R.; Vanderspek, Roland K.; Latham, David W.; Winn, Joshua N.; Seager, Sara; Jenkins, Jon M.; Barclay, Thomas; Bouma, Luke G.; Christiansen, Jessie L.; Guerrero, Natalia; Rose, Mark E.
    Hot jupiters (P < 10 d, M > 60 M.) are almost always found alone around their stars, but four out of hundreds known have inner companion planets. These rare companions allow us to constrain the hot jupiter's formation history by ruling out high-eccentricity tidal migration. Less is known about inner companions to hot Saturn-mass planets. We report here the discovery of the TOI-2000 system, which features a hot Saturn-mass planet with a smaller inner companion. The mini-neptune TOI-2000 b (2.70 +/- 0.15 R-circle plus, 11.0 +/- 2.4 M.) is in a 3.10-d orbit, and the hot saturn TOI-2000 c (8.14(+0.31) (-0.30) R-circle plus, 81.7(-4.6)(+4.7) M.) is in a 9.13-d orbit. Both planets transit their host star TOI-2000 (TIC 371188886, V = 10.98, TESS magnitude = 10.36), a metal-rich ([Fe/H] = 0.439 (+0.041)(-0.043)) G dwarf 173 pc away. TESS observed the two planets in sectors 9-11 and 36-38, and we followed up with groundbased photometry, spectroscopy, and speckle imaging. Radial velocities from CHIRON, FEROS, and HARPS allowed us to confirm both planets by direct mass measurement. In addition, we demonstrate constraining planetary and stellar parameters with MIST stellar evolutionary tracks through Hamiltonian Monte Carlo under the PYMC framework, achieving higher sampling efficiency and shorter run time compared to traditional Markov chain Monte Carlo. Having the brightest host star in the V band among similar systems, TOI-2000 b and c are superb candidates for atmospheric characterization by the JWST, which can potentially distinguish whether they formed together or TOI-2000 c swept along material during migration to form TOI-2000 b.
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    Stellar Astrophysics and Exoplanet Science with the Maunakea Spectroscopic Explorer (MSE)
    (2019) Bergemann, Maria; Huber, Daniel; Adibekyan, Vardan; Angelou, George; Barría, Daniela; Beers, Timothy C.; Beck, Paul G.; Bellinger, Earl P.; Bestenlehner, Joachim M.; Bitsch, Bertram; Burgasser, Adam; Buzasi, Derek; Cassisi, Santi; Catelan, Marcio; Escorza, Ana; Fleming, Scott W.; Gänsicke, Boris T.; Gandolfi, Davide; García, Rafael A.; Gieles, Mark; Karakas, Amanda; Lebreton, Yveline; Lodieu, Nicolas; Melis, Carl; Merle, Thibault; Mészáros, Szabolcs; Miglio, Andrea; Molaverdikhani, Karan; Monier, Richard; Morel, Thierry; Neilson, Hilding R.; Oshagh, Mahmoudreza; Rybizki, Jan; Serenelli, Aldo; Smiljanic, Rodolfo; Szabó, Gyula M.; Toonen, Silvia; Tremblay, Pier-Emmanuel; Valentini, Marica; Van Eck, Sophie; Zwintz, Konstanze; Bayo, Amelia; Cami, Jan; Casagrande, Luca; Gabdeev, Maksim; Gaulme, Patrick; Guiglion, Guillaume; Handler, Gerald; Hillenbrand, Lynne; Yildiz, Mutlu; Marley, Mark; Mosser, Benoit; Price-Whelan, Adrian M.; Prsa, Andrej; Hernández Santisteban, Juan V.; Silva Aguirre, Victor; Sobeck, Jennifer; Stello, Dennis; Szabo, Robert; Tsantaki, Maria; Villaver, Eva; Wright, Nicholas J.; Xu, Siyi; Zhang, Huawei; Anguiano, Borja; Bedell, Megan; Chaplin, Bill; Collet, Remo; Kamath, Devika; Martell, Sarah; Sousa, Sérgio G.; Ting, Yuan-Sen; Venn, Kim
    The Maunakea Spectroscopic Explorer (MSE) is a planned 11.25-m aperture facility with a 1.5 square degree field of view that will be fully dedicated to multi-object spectroscopy. A rebirth of the 3.6m Canada-France-Hawaii Telescope on Maunakea, MSE will use 4332 fibers operating at three different resolving powers (R ~ 2500, 6000, 40000) across a wavelength range of 0.36-1.8mum, with dynamical fiber positioning that allows fibers to match the exposure times of individual objects. MSE will enable spectroscopic surveys with unprecedented scale and sensitivity by collecting millions of spectra per year down to limiting magnitudes of g ~ 20-24 mag, with a nominal velocity precision of ~100 m/s in high-resolution mode. This white paper describes science cases for stellar astrophysics and exoplanet science using MSE, including the discovery and atmospheric characterization of exoplanets and substellar objects, stellar physics with star clusters, asteroseismology of solar-like oscillators and opacity-driven pulsators, studies of stellar rotation, activity, and multiplicity, as well as the chemical characterization of AGB and extremely metal-poor stars....