Browsing by Author "Beichman, Charles A."

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    197 CANDIDATES AND 104 VALIDATED PLANETS IN K2's FIRST FIVE FIELDS
    (2016) Crossfield, Ian J. M.; Ciardi, David R.; Petigura, Erik A.; Sinukoff, Evan; Schlieder, Joshua E.; Howard, Andrew W.; Beichman, Charles A.; Isaacson, Howard; Dressing, Courtney D.; Christiansen, Jessie L.; Fulton, Benjamin J.; Lepine, Sebastien; Weiss, Lauren; Hirsch, Lea; Livingston, John; Baranec, Christoph; Law, Nicholas M.; Riddle, Reed; Ziegler, Carl; Howell, Steve B.; Horch, Elliott; Everett, Mark; Teske, Johanna; Martinez, Arturo O.; Obermeier, Christian; Benneke, Bjorn; Scott, Nic; Deacon, Niall; Aller, Kimberly M.; Hansen, Brad M. S.; Mancini, Luigi; Ciceri, Simona; Brahm, Rafael; Jordan, Andres; Knutson, Heather A.; Henning, Thomas; Bonnefoy, Michael; Liu, Michael C.; Crepp, Justin R.; Lothringer, Joshua; Hinz, Phil; Bailey, Vanessa; Skemer, Andrew; Defrere, Denis
    We present 197 planet candidates discovered using data from the first year of the NASA K2 mission (Campaigns 0-4), along with the results of an intensive program of photometric analyses, stellar spectroscopy, high-resolution imaging, and statistical validation. We distill these candidates into sets of 104 validated planets (57 in multi-planet systems), 30 false positives, and 63 remaining candidates. Our validated systems span a range of properties, with median values of R-P = 2.3 R-circle plus, P = 8.6 days, T-eff = 5300 K, and Kp = 12.7 mag. Stellar spectroscopy provides precise stellar and planetary parameters for most of these systems. We show that K2 has increased by 30% the number of small planets known to orbit moderately bright stars (1-4 R-circle plus, Kp = 9-13. mag). Of particular interest are 76 planets smaller than 2 R-circle plus, 15 orbiting stars brighter than Kp = 11.5. mag, 5 receiving Earth-like irradiation levels, and several multi-planet systems-including 4 planets orbiting the M dwarf K2-72 near mean-motion resonances. By quantifying the likelihood that each candidate is a planet we demonstrate that our candidate sample has an overall false positive rate of 15%-30%, with rates substantially lower for small candidates (<2 R-circle plus) and larger for candidates with radii >8 R-circle plus and/or with P < 3 days. Extrapolation of the current planetary yield suggests that K2 will discover between 500 and 1000 planets in its planned four-year mission, assuming sufficient follow-up resources are available. Efficient observing and analysis, together with an organized and coherent follow-up strategy, are essential for maximizing the efficacy of planet-validation efforts for K2, TESS, and future large-scale surveys.
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    An ultrahot Neptune in the Neptune desert
    (2020) Jenkins, James S.; Diaz, Matias R.; Kurtovic, Nicolas T.; Espinoza, Nestor; Vines, Jose I.; Rojas, Pablo A. Pena; Brahm, Rafael; Torres, Pascal; Cortes-Zuleta, Pia; Soto, Maritza G.; Lopez, Eric D.; King, George W.; Wheatley, Peter J.; Winn, Joshua N.; Ciardi, David R.; Ricker, George; Vanderspek, Roland; Latham, David W.; Seager, Sara; Jenkins, Jon M.; Beichman, Charles A.; Bieryla, Allyson; Burke, Christopher J.; Christiansen, Jessie L.; Henze, Christopher E.; Klaus, Todd C.; McCauliff, Sean; Mori, Mayuko; Narita, Norio; Nishiumi, Taku; Tamura, Motohide; de Leon, Jerome Pitogo; Quinn, Samuel N.; Villasenor, Jesus Noel; Vezie, Michael; Lissauer, Jack J.; Collins, Karen A.; Collins, Kevin I.; Isopi, Giovanni; Mallia, Franco; Ercolino, Andrea; Petrovich, Cristobal; Jordan, Andres; Acton, Jack S.; Armstrong, David J.; Bayliss, Daniel; Bouchy, Francois; Belardi, Claudia; Bryant, Edward M.; Burleigh, Matthew R.; Cabrera, Juan; Casewell, Sarah L.; Chaushev, Alexander; Cooke, Benjamin F.; Eigmueller, Philipp; Erikson, Anders; Foxell, Emma; Gansicke, Boris T.; Gill, Samuel; Gillen, Edward; Guenther, Maximilian N.; Goad, Michael R.; Hooton, Matthew J.; Jackman, James A. G.; Louden, Tom; McCormac, James; Moyano, Maximiliano; Nielsen, Louise D.; Pollacco, Don; Queloz, Didier; Rauer, Heike; Raynard, Liam; Smith, Alexis M. S.; Tilbrook, Rosanna H.; Titz-Weider, Ruth; Turner, Oliver; Udry, Stephane; Walker, Simon. R.; Watson, Christopher A.; West, Richard G.; Palle, Enric; Ziegler, Carl; Law, Nicholas; Mann, Andrew W.
    About 1 out of 200 Sun-like stars has a planet with an orbital period shorter than one day: an ultrashort-period planet(1,2). All of the previously known ultrashort-period planets are either hot Jupiters, with sizes above 10 Earth radii (R-circle plus), or apparently rocky planets smaller than 2 R-circle plus. Such lack of planets of intermediate size (the `hot Neptune desert') has been interpreted as the inability of low-mass planets to retain any hydrogen/ helium (H/He) envelope in the face of strong stellar irradiation. Here we report the discovery of an ultrashort-period planet with a radius of 4.6 R-circle plus and a mass of 29 M-circle plus, firmly in the hot Neptune desert. Data from the Transiting Exoplanet Survey Satellite(3) revealed transits of the bright Sun-like star LTT 9779 every 0.79 days. The planet's mean density is similar to that of Neptune, and according to thermal evolution models, it has a H/He-rich envelope constituting 9.0(-2.9)(+2.7) % of the total mass. With an equilibrium temperature around 2,000 K, it is unclear how this `ultrahot Neptune' managed to retain such an envelope. Follow-up observations of the planet's atmosphere to better understand its origin and physical nature will be facilitated by the star's brightness (V-mag = 9.8).
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    Author correction: An ultrahot Neptune in the Neptune desert
    (2020) Jenkins, James S.; Díaz, Matías R.; Kurtovic, Nicolás T.; Espinoza, Néstor; Vines, Jose I.; Peña Rojas, Pablo A.; Brahm, Rafael; Torres, Pascal; Cortés Zuleta, Pía ; Soto, Maritza G.; López, Eric D.; King, George W.; Wheatley, Peter J.; Winn, Joshua N.; Ciardi, David R.; Ricker, George; Vanderspek, Roland; Latham, David W.; Seager, Sara; Jenkins, Jon M.; Beichman, Charles A.; Bieryla, Allyson; Burke, Christopher J.; Christiansen , Jessie L.; Henze, Christopher E.; Klaus, Todd C.; McCaulif, Sean; Mori, Mayuko; Narita, Norio; Nishiumi, Taku; Tamura, Motohide; Pitogo de Leon, Jerome; Quinn, Samuel N.; Villaseñor, Jesus Noel; Vezie, Michael; Lissauer, Jack J.; Collins, Karen A.; Collins, Kevin I.; Isopi, Giovanni; Mallia, Franco; Ercolino, Andrea; Petrovich, Cristobal; Jordán, Andrés; Acton, Jack S.; Armstrong, David J.; Bayliss, Daniel; Bouchy, François; Belardi, Claudia; Bryant, Edward M.; Burleigh, Matthew R.; Cabrera, Juan; Casewell, Sarah L.; Chaushev, Alexander; Cooke, Benjamin F.; Eigmüller, Philipp; Erikson, Anders; Foxell, Emma; Gänsicke, Boris T.; Gill, Samuel; Gillen, Edward; Günther, Maximilian N.; Goad, Michael R.; Hooton, Matthew J.; Jackman, James A. G.; Louden, Tom; McCormac, James; Moyano, Maximiliano; Nielsen, Louise D.; Pollacco, Don; Queloz, Didier; Rauer, Heike; Raynard, Liam; Smith, Alexis M. S.; Tilbrook, Rosanna H.; Titz Weider, Ruth; Turner, Oliver; Udry, Stéphane; Walker, Simon R.; Watson, Christopher A.; West, Richard G.; Palle, Enric; Ziegler, Carl; Law, Nicholas; Mann, Andrew W.
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    Spitzer Microlensing Parallax for OGLE-2017-BLG-0896 Reveals a Counter-rotating Low-mass Brown Dwarf
    (2019) Shvartzvald, Yossi; Yee, Jennifer C.; Skowron, Jan; Lee, Chung-Uk; Udalski, Andrzej; Novati, Sebastiano Calchi; Bozza, Valerio; Beichman, Charles A.; Bryden, Geoffery; Rabus, Markus
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    VaTEST I: validation of sub-Saturn exoplanet TOI-181b in narrow orbit from its host star
    (2023) Mistry, Priyashkumar; Pathak, Kamlesh; Lekkas, Georgios; Prasad, Aniket; Bhattarai, Surendra; Maity, Mousam; Beichman, Charles A.; Ciardi, David R.; Evans, Phil; Bieryla, Allyson; Eastman, Jason D.; Esquerdo, Gilbert A.; Lucero, Jennifer P.
    We present here a validation of sub-Saturn exoplanet TOI-181b orbiting a K spectral type star TOI-181 (mass: 0.822 +/- 0.04 M-circle dot, radius: 0.745 +/- 0.02 R-circle dot, temperature: 4994 +/- 50 K) as a part of Validation of Transiting Exoplanets using Statistical Tools (VaTEST) project. TOI-181b is a planet with radius 6.95 +/- 0.08 R-circle plus, mass 46.16 +/- 2.71 M-circle plus, orbiting in a slightly eccentric orbit with eccentricity 0.15 +/- 0.06 and semimajor axis of 0.054 +/- 0.004 au, with an orbital period of 4.5320 +/- 0.000002 d. The transit photometry data were collected using Transiting Exoplanet Survey Satellite (TESS) and spectroscopic data for radial velocity analysis were collected using The European Southern Observatory's (ESO) High Accuracy Radial Velocity Planet Searcher (HARPS) telescope. Based on the radial velocity best-fit model we measured RV semi-amplitude to be 20.56 +/- 2.37 m s(-1). Additionally, we used VESPA and TRICERATOPS to compute the False Positive Probability (FPP), and the findings were FPP values of 1.68 x 10(-14) and 3.81 x 10(-04), respectively, which are significantly lower than the 1 per cent threshold. The finding of TOI-181b is significant in the perspective of future work on the formation and migration history of analogous planetary systems since warm sub-Saturns are uncommon in the known sample of exoplanets.