Browsing by Author "Brahm, Rafael"

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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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    A 2:1 Mean-motion Resonance Super-Jovian Pair Revealed by TESS, FEROS, and HARPS
    (2023) Bozhilov, Vladimir; Antonova, Desislava; Hobson, Melissa J.; Brahm, Rafael; Jordan, Andres; Henning, Thomas; Eberhardt, Jan; Rojas, Felipe I.; Batygin, Konstantin; Torres-Miranda, Pascal; Stassun, Keivan G.; Millholland, Sarah C.; Stoeva, Denitza; Minev, Milen; Espinoza, Nestor; Ricker, George R.; Latham, David W.; Dragomir, Diana; Kunimoto, Michelle; Jenkins, Jon M.; Ting, Eric B.; Seager, Sara; Winn, Joshua N.; Villasenor, Jesus Noel; Bouma, Luke G.; Medina, Jennifer; Trifonov, Trifon
    We report the discovery of a super-Jovian 2:1 mean-motion resonance (MMR) pair around the G-type star TIC 279401253, whose dynamical architecture is a prospective benchmark for planet formation and orbital evolution analysis. The system was discovered thanks to a single-transit event recorded by the Transiting Exoplanet Survey Satellite mission, which pointed to a Jupiter-sized companion with poorly constrained orbital parameters. We began ground-based precise radial velocity (RV) monitoring with HARPS and FEROS within the Warm gIaNts with tEss survey to constrain the transiting body's period, mass, and eccentricity. The RV measurements revealed not one but two massive planets with periods of 76.80(-0.06)(+0.06) and 155.3(-0.7)(+0.7) days, respectively. A combined analysis of transit and RV data yields an inner transiting planet with a mass of 6.14(-0.42)(+0.39) M-Jup and a radius of 1.00(-0.04)(+0.04) R-Jup, and an outer planet with a minimum mass of 8.02(-0.18)(+0.18) M-Jup, indicating a massive giant pair. A detailed dynamical analysis of the system reveals that the planets are locked in a strong firstorder, eccentricity-type 2:1 MMR, which makes TIC 279401253 one of the rare examples of truly resonant architectures supporting disk-induced planet migration. The bright host star, V approximate to 11.9 mag, the relatively short orbital period (P-b = 76.80(-0.06)(+0.06) days), and pronounced eccentricity (e = 0.448(-0.029)(+0.029)) make the transiting planet a valuable target for atmospheric investigation with the James Webb Space Telescope and ground-based extremely large telescopes.
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    A long-period transiting substellar companion in the super-Jupiters to brown dwarfs mass regime and a prototypical warm-Jupiter detected by TESS
    (2024) Jones, Matias I.; Reinarz, Yared; Brahm, Rafael; Tala Pinto, Marcelo; Eberhardt, Jan; Rojas, Felipe; Triaud, Amaury H. M. J.; Gupta, Arvind F.; Ziegler, Carl; Hobson, Melissa J.; Jordan, Andres; Henning, Thomas; Trifonov, Trifon; Schlecker, Martin; Espinoza, Nestor; Torres-Miranda, Pascal; Sarkis, Paula; Ulmer-Moll, Solene; Lendl, Monika; Uzundag, Murat; Moyano, Maximiliano; Hesse, Katharine; Caldwell, Douglas A.; Shporer, Avi; Lund, Michael B.; Jenkins, Jon M.; Seager, Sara; Winn, Joshua N.; Ricker, George R.; Burke, Christopher J.; Figueira, Pedro; Psaridi, Angelica; Al Moulla, Khaled; Mounzer, Dany; Standing, Matthew R.; Martin, David V.; Dransfield, Georgina; Baycroft, Thomas; Dragomir, Diana; Boyle, Gavin; Suc, Vincent; Mann, Andrew W.; Timmermans, Mathilde; Ducrot, Elsa; Hooton, Matthew J.; Zuniga-Fernandez, Sebastian; Sebastian, Daniel; Gillon, Michael; Queloz, Didier; Carson, Joe; Lissauer, Jack J.
    We report on the confirmation and follow-up characterization of two long-period transiting substellar companions on low-eccentricity orbits around TIC 4672985 and TOI-2529, whose transit events were detected by the TESS space mission. Ground-based photometric and spectroscopic follow-up from different facilities, confirmed the substellar nature of TIC 4672985 b, a massive gas giant in the transition between the super-Jupiters and brown dwarfs mass regime. From the joint analysis we derived the following orbital parameters: P = 69.0480(-0.0005)(+0.0004) d, M-p = 12.74(-1.01)(+1.01) M-J, R-p = 1.026(-0.067)(+0.065) R-J and e = 0.018(-0.004)(+0.004). In addition, the RV time series revealed a significant trend at the similar to 350 m s(-1) yr(-1) level, which is indicative of the presence of a massive outer companion in the system. TIC 4672985 b is a unique example of a transiting substellar companion with a mass above the deuterium-burning limit, located beyond 0.1 AU and in a nearly circular orbit. These planetary properties are difficult to reproduce from canonical planet formation and evolution models. For TOI-2529 b, we obtained the following orbital parameters: P = 64.5949(-0.0003)(+0.0003) d, M-p = 2.340(-0.195)(+0.197) M-J, R-p = 1.030(-0.050)(+0.050) R-J and e = 0.021(-0.015)(+0.024), making this object a new example of a growing population of transiting warm giant planets.
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    A Pair of Warm Giant Planets near the 2:1 Mean Motion Resonance around the K-dwarf Star TOI-2202*
    (2021) Trifonov, Trifon; Brahm, Rafael; Espinoza, Nestor; Henning, Thomas; Jordan, Andres; Nesvorny, David; Dawson, Rebekah I.; Lissauer, Jack J.; Lee, Man Hoi; Kossakowski, Diana; Rojas, Felipe I.; Hobson, Melissa J.; Sarkis, Paula; Schlecker, Martin; Bitsch, Bertram; Bakos, Gaspar A.; Barbieri, Mauro; Bhatti, W.; Butler, R. Paul; Crane, Jeffrey D.; Nandakumar, Sangeetha; Diaz, Matias R.; Shectman, Stephen; Teske, Johanna; Torres, Pascal; Suc, Vincent; Vines, Jose I.; Wang, Sharon X.; Ricker, George R.; Shporer, Avi; Vanderburg, Andrew; Dragomir, Diana; Vanderspek, Roland; Burke, Christopher J.; Daylan, Tansu; Shiao, Bernie; Jenkins, Jon M.; Wohler, Bill; Seager, Sara; Winn, Joshua N.
    TOI-2202 b is a transiting warm Jovian-mass planet with an orbital period of P = 11.91 days identified from the Full Frame Images data of five different sectors of the TESS mission. Ten TESS transits of TOI-2202 b combined with three follow-up light curves obtained with the CHAT robotic telescope show strong transit timing variations (TTVs) with an amplitude of about 1.2 hr. Radial velocity follow-up with FEROS, HARPS, and PFS confirms the planetary nature of the transiting candidate (a (b) = 0.096 +/- 0.001 au, m (b) = 0.98 +/- 0.06 M (Jup)), and a dynamical analysis of RVs, transit data, and TTVs points to an outer Saturn-mass companion (a (c) = 0.155 +/- 0.002 au, m (c) = 0.37 +/- 0.10 M (Jup)) near the 2:1 mean motion resonance. Our stellar modeling indicates that TOI-2202 is an early K-type star with a mass of 0.82 M (circle dot), a radius of 0.79 R (circle dot), and solar-like metallicity. The TOI-2202 system is very interesting because of the two warm Jovian-mass planets near the 2:1 mean motion resonance, which is a rare configuration, and their formation and dynamical evolution are still not well understood.
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    A Transiting Warm Giant Planet around the Young Active Star TOI-201
    (2021) Hobson, Melissa J.; Brahm, Rafael; Jordan, Andres; Espinoza, Nestor; Kossakowski, Diana; Henning, Thomas; Rojas, Felipe; Schlecker, Martin; Sarkis, Paula; Trifonov, Trifon; Thorngren, Daniel; Binnenfeld, Avraham; Shahaf, Sahar; Zucker, Shay; Ricker, George R.; Latham, David W.; Seager, S.; Winn, Joshua N.; Jenkins, Jon M.; Addison, Brett; Bouchy, Francois; Bowler, Brendan P.; Briegal, Joshua T.; Bryant, Edward M.; Collins, Karen A.; Daylan, Tansu; Grieves, Nolan; Horner, Jonathan; Huang, Chelsea; Kane, Stephen R.; Kielkopf, John; McLean, Brian; Mengel, Matthew W.; Nielsen, Louise D.; Okumura, Jack; Jones, Matias; Plavchan, Peter; Shporer, Avi; Smith, Alexis M. S.; Tilbrook, Rosanna; Tinney, C. G.; Twicken, Joseph D.; Udry, Stephane; Unger, Nicolas; West, Richard; Wittenmyer, Robert A.; Wohler, Bill; Torres, Pascal; Wright, Duncan J.
    We present the confirmation of the eccentric warm giant planet TOI-201 b, first identified as a candidate in Transiting Exoplanet Survey Satellite photometry (Sectors 1-8, 10-13, and 27-28) and confirmed using groundbased photometry from Next Generation Transit Survey and radial velocities from FEROS, HARPS, CORALIE, and MINERVA-Australis. TOI-201 b orbits a young (0.87(-0.49)(+0.46)) and bright (V = 9.07 mag) F-type star with a 52.9781 day period. The planet has a mass of 0.42(-0.03)(+0.05) M-J, a radius of 1.008(-0.015)(+0.012) R-J, and an orbital eccentricity of 0.28(-0.09)(+0.06); it appears to still be undergoing fairly rapid cooling, as expected given the youth of the host star. The star also shows long-term variability in both the radial velocities and several activity indicators, which we attribute to stellar activity. The discovery and characterization of warm giant planets such as TOI-201 b are important for constraining formation and evolution theories for giant planets.
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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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    Distinguishing a planetary transit from false positives: a Transformer-based classification for planetary transit signals
    (2023) Salinas, Helem; Pichara, Karim; Brahm, Rafael; Perez-Galarce, Francisco; Mery, Domingo
    Current space-based missions, such as the Transiting Exoplanet Survey Satellite (TESS), provide a large database of light curves that must be analysed efficiently and systematically. In recent years, deep learning (DL) methods, particularly convolutional neural networks (CNN), have been used to classify transit signals of candidate exoplanets automatically. However, CNNs have some drawbacks; for example, they require many layers to capture dependencies on sequential data, such as light curves, making the network so large that it eventually becomes impractical. The self-attention mechanism is a DL technique that attempts to mimic the action of selectively focusing on some relevant things while ignoring others. Models, such as the Transformer architecture, were recently proposed for sequential data with successful results. Based on these successful models, we present a new architecture for the automatic classification of transit signals. Our proposed architecture is designed to capture the most significant features of a transit signal and stellar parameters through the self-attention mechanism. In addition to model prediction, we take advantage of attention map inspection, obtaining a more interpretable DL approach. Thus, we can identify the relevance of each element to differentiate a transit signal from false positives, simplifying the manual examination of candidates. We show that our architecture achieves competitive results concerning the CNNs applied for recognizing exoplanetary transit signals in data from the TESS telescope. Based on these results, we demonstrate that applying this state-of-the-art DL model to light curves can be a powerful technique for transit signal detection while offering a level of interpretability.
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    Early optical spectra of nova V1369 Cen show the presence of lithium
    (2015) Izzo, Luca; Della Valle, Massimo; Mason, Elena; Matteucci, F.; Romano, Donatella; Pasquini, Luca; Vanzi, Leonardo; Jordán Colzani, Andrés Cristóbal; Fernandez, José Miguel; Bluhm, Paz; Brahm, Rafael; Espinoza, Nestor; Williams, Robert
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    Evolution of BD-14 3065b (TOI-4987b) from giant planet to brown dwarf as possible evidence of deuterium burning at old stellar ages
    (2024) Subjak, Jan; Latham, David W.; Quinn, Samuel N.; Berlind, Perry; Calkins, Michael L.; Esquerdo, Gilbert A.; Brahm, Rafael; Caballero, Jose A.; Collins, Karen A.; Guenther, Eike; Janik, Jan; Kabath, Petr; Schwarz, Richard P.; Tan, Thiam-Guan; Vanzi, Leonardo; Zambelli, Roberto; Ziegler, Carl; Jenkins, Jon M.; Mireles, Ismael; Seager, Sara; Shporer, Avi; Striegel, Stephanie; Winn, Joshua N.
    The present study confirms BD-14 3065b as a transiting planet-brown dwarf in a triple-star system, with a mass near the deuterium-burning boundary. BD-14 3065b has the largest radius observed within the sample of giant planets and brown dwarfs around post-main sequence stars. Its orbital period is 4.3 days and it transits a subgiant F-type star with a mass of M-* = 1.41 +/- 0.05 M-circle dot, a radius of R-* = 2.35 +/- 0.08 R-circle dot, an effective temperature of T-eff = 6935 +/- 90 K, and a metallicity of -0.34 +/- 0.05 dex. By combining TESS photometry with high-resolution spectra acquired with the TRES and Pucheros+ spectrographs, we measured a mass of M-p = 12.37 +/- 0.92 M-Jup and a radius of R-p = 1.926 +/- 0.094 R-Jup. Our discussion of potential processes that could be responsible for the inflated radius led us to conclude that deuterium burning is a plausible explanation for the heating taking place in BD-14 3065b's interior. Detections of the secondary eclipse with TESS photometry enabled a precise determination of the eccentricity, e(p) = 0.066 +/- 0.011, and reveal that BD-14 3065b has a brightness temperature of 3520 +/- 130 K. With its unique characteristics, BD-14 3065b presents an excellent opportunity to study its atmosphere via thermal emission spectroscopy.
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    HATS-38 b and WASP-139 b Join a Growing Group of Hot Neptunes on Polar Orbits
    (2024) Espinoza-Retamal, Juan I.; Stefansson, Gudmundur; Petrovich, Cristobal; Brahm, Rafael; Jordan, Andres; Sedaghati, Elyar; Lucero, Jennifer P.; Pinto, Marcelo Tala; Munoz, Diego J.; Boyle, Gavin; Leiva, Rodrigo; Suc, Vincent
    We constrain the sky-projected obliquities of two low-density hot Neptune planets, HATS-38 b and WASP-139 b, orbiting nearby G and K stars using Rossiter-McLaughlin (RM) observations with VLT/ESPRESSO, yielding lambda=-108(-16)(+11) deg and -85.6(-4.2)(+7.7) deg, respectively. To model the RM effect, we use a new publicly available code, ironman, which is capable of jointly fitting transit photometry, Keplerian radial velocities, and RM effects. WASP-139 b has a residual eccentricity e=0.103(-0.041)(+0.050) while HATS-38 b has an eccentricity of e=0.112(-0.070)(+0.072), which is compatible with a circular orbit given our data. Using the obliquity constraints, we show that they join a growing group of hot and low-density Neptunes on polar orbits. We use long-term radial velocities to rule out companions with masses similar to 0.3-50 M-J within similar to 10 au. We show that the orbital architectures of the two Neptunes can be explained with high-eccentricity migration from greater than or similar to 2 au driven by an unseen distant companion. If HATS-38b has no residual eccentricity, its polar and circular orbit can also be consistent with a primordial misalignment. Finally, we performed a hierarchical Bayesian modeling of the true obliquity distribution of Neptunes and found suggestive evidence for a higher preponderance of polar orbits of hot Neptunes compared to Jupiters. However, we note that the exact distribution is sensitive to the choice of priors, highlighting the need for additional obliquity measurements of Neptunes to robustly compare the hot Neptune obliquity distribution to Jupiters.
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    Hats-3b: An inflated hot jupiter transiting an F-type star*
    (2013) Bayliss, D.; Zhou, Guangyuan; Penev, Kaloyan; Bakos, G. Á.; Hartman, J. D.; Jordán Colzani, Andrés Cristóbal; Mancini, Luigi; Mohler-Fischer, Maren; Suc, Vincent; Rabus, Markus; Béky, Bence; Csubry, Zoltan; Buchhave, L.; Henning, T.; Nikolov, Nikolay; Csák, B.; Brahm, Rafael; Espinoza Pérez, Néstor
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    HD 2685 b: a hot Jupiter orbiting an early F-type star detected by TESS
    (2019) Jones, Matias, I; Brahm, Rafael; Espinoza, Nestor; Wang, Songhu; Shporer, Avi; Henning, Thomas; Jordan, Andres; Sarkis, Paula; Paredes, Leonardo A.; Hodari-Sadiki, James; Henrys, Todd; Cruz, Bryndis; Nielsen, Louise D.; Bouchy, Francois; Pepe, Francesco; Segransan, Damien; Turner, Oliver; Udry, Stephane; Marmier, Maxime; Lovis, Christophe; Bakos, Gaspar; Osip, David; Suc, Vincent; Ziegler, Carl; Tokovinin, Andrei; Law, Nick M.; Mann, Andrew W.; Relles, Howard; Collins, Karen A.; Bayliss, Daniel; Sedaghati, Elyar; Latham, David W.; Seager, Sara; Winn, Joshua N.; Jenkins, Jon M.; Smith, Jeffrey C.; Davies, Misty; Tenenbaum, Peter; Dittmann, Jason; Vanderburg, Andrew; Christiansen, Jessie L.; Haworth, Kari; Doty, John; Furesz, Gabor; Laughlin, Greg; Matthews, Elisabeth; Crossfield, Ian; Howell, Steve; Ciardi, David; Gonzales, Erica; Matson, Rachel; Beichman, Charles; Schlieder, Joshua
    We report on the confirmation of a transiting giant planet around the relatively hot (T-eff = 6801 +/- 76 K) star HD 2685, whose transit signal was detected in Sector 1 data of NASA's TESS mission. We confirmed the planetary nature of the transit signal using Doppler velocimetric measurements with CHIRON, CORALIE, and FEROS, as well as using photometric data obtained with the Chilean-Hungarian Automated Telescope and the Las Cumbres Observatory. From the joint analysis of photometry and radial velocities, we derived the following parameters for HD 2685 b: P =4.12688(-0.00004)(+0.00005) days, e =0.091(-0.047)(+0.039), Mp = 1.17 +/- 0.12 M-J, and R-p =1.44 +/- 0.05 R-J. This system is a typical example of an inflated transiting hot Jupiter in a low-eccentricity orbit. Based on the apparent visual magnitude (V = 9.6 mag) of the host star, this is one of the brightest known stars hosting a transiting hot Jupiter, and it is a good example of the upcoming systems that will be detected by TESS during the two-year primary mission. This is also an excellent target for future ground- and space-based atmospheric characterization as well as a good candidate for measuring the projected spin-orbit misalignment angle through the Rossiter-McLaughlin effect.
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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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    K2-280 b - a low density warm sub-Saturn around a mildly evolved star
    (2020) Nowak, Grzegorz; Palle, Enric; Gandolfi, Davide; Deeg, Hans J.; Hirano, Teruyuki; Barragan, Oscar; Kuzuhara, Masayuki; Dai, Fei; Luque, Rafael; Persson, Carina M.; Fridlund, Malcolm; Johnson, Marshall C.; Korth, Judith; Livingston, John H.; Grziwa, Sascha; Mathur, Savita; Hatzes, Artie P.; Prieto-Arranz, Jorge; Nespral, David; Hidalgo, Diego; Hjorth, Maria; Albrecht, Simon; Van Eylen, Vincent; Lam, Kristine W. F.; Cochran, William D.; Esposito, Massimiliano; Csizmadia, Szilard; Guenther, Eike W.; Kabath, Petr; Blay, Pere; Brahm, Rafael; Jordan, Andres; Espinoza, Nestor; Rojas, Felipe; Casasayas Barris, Nuria; Rodler, Florian; Alonso Sobrino, Roi; Cabrera, Juan; Carleo, Ilaria; Chaushev, Alexander; de Leon, Jerome; Eigmueller, Philipp; Endl, Michael; Erikson, Anders; Fukui, Akihiko; Georgieva, Iskra; Gonzalez-Cuesta, Lucia; Knudstrup, Emil; Lund, Mikkel N.; Montanes Rodriguez, Pilar; Murgas, Felipe; Narita, Norio; Niraula, Prajwal; Paetzold, Martin; Rauer, Heike; Redfield, Seth; Ribas, Ignasi; Skarka, Marek; Smith, Alexis M. S.; Subjak, Jano
    We present an independent discovery and detailed characterization of K2-280 b, a transiting low density warm sub-Saturn in a 19.9-d moderately eccentric orbit (e = 0.35(-0.04)(+0.05)) from K2 campaign 7. A joint analysis of high precision HARPS, HARPS-N, and FIES radial velocity measurements and K2 photometric data indicates that K2-280 b has a radius of R-b = 7.50 +/- 0.44 R-circle plus and a mass of M-b = 37.1 +/- 5.6 M-circle plus, yielding a mean density of rho(b) = 0.48(-0.10)(+0.13) g cm(-3). The host star is a mildly evolved G7 star with an effective temperature of T-eff = 5500 +/- 100 K, a surface gravity of log g(star) = 4.21 +/- 0.05 (cgs), and an iron abundance of [Fe/H] = 0.33 +/- 0.08 dex, and with an inferred mass of M-star = 1.03 +/- 0.03 M-circle dot and a radius of R-star = 1.28 +/- 0.07 R-circle dot. We discuss the importance of K2-280 b for testing formation scenarios of sub-Saturn planets and the current sample of this intriguing group of planets that are absent in the Solar system.
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    Mass determination of two Jupiter-sized planets orbiting slightly evolved stars: TOI-2420 b and TOI-2485 b
    (2024) Carleo, Ilaria; Barragan, Oscar; Persson, Carina M.; Fridlund, Malcolm; Lam, Kristine W. F.; Messina, Sergio; Gandolfi, Davide; Smith, Alexis M. S.; Johnson, Marshall C.; Cochran, William; Osborne, Hannah L. M.; Brahm, Rafael; Ciardi, David R.; Collins, Karen A.; Everett, Mark E.; Giacalone, Steven; Guenther, Eike W.; Hatzes, Artie; Hellier, Coel; Horner, Jonathan; Kabath, Petr; Korth, Judith; MacQueen, Phillip; Masseron, Thomas; Murgas, Felipe; Nowak, Grzegorz; Rodriguez, Joseph E.; Watkins, Cristilyn N.; Wittenmyer, Rob; Zhou, George; Ziegler, Carl; Bieryla, Allyson; Boyd, Patricia T.; Clark, Catherine A.; Dressing, Courtney D.; Eastman, Jason D.; Eberhardt, Jan; Endl, Michael; Espinoza, Nestor; Fausnaugh, Michael; Guerrero, Natalia M.; Henning, Thomas; Hesse, Katharine; Hobson, Melissa J.; Howell, Steve B.; Jordan, Andres; Latham, David W.; Lund, Michael B.; Mireles, Ismael; Narita, Norio; Tala Pinto, Marcelo; Pugh, Teznie; Quinn, Samuel N.; Ricker, George; Rodriguez, David R.; Rojas, Felipe I.; Rose, Mark E.; Rudat, Alexander; Sarkis, Paula; Savel, Arjun B.; Schlecker, Martin; Schwarz, Richard P.; Seager, Sara; Shporer, Avi; Smith, Jeffrey C.; Stassun, Keivan G.; Stockdale, Chris; Trifonov, Trifon; Vanderspek, Roland; Winn, Joshua N.; Wright, Duncan
    Context. Hot and warm Jupiters might have undergone the same formation and evolution path, but the two populations exhibit different distributions of orbital parameters. This challenges our understanding of their actual origin. Aims. We report the results of our warm Jupiters survey, which was carried out with the CHIRON spectrograph within the KESPRINT collaboration. We addressed the question of the population origin by studying two planets that might help to bridge the gap between the two populations. Methods. We confirm two planets and determine their mass. One is a hot Jupiter (with an orbital period shorter than 10 days), TOI-2420 b, and the other is a warm Jupiter, TOI-2485 b. We analyzed them using a wide variety of spectral and photometric data in order to characterize these planetary systems. Results. We found that TOI-2420 b has an orbital period of P-b=5.8 days, a mass of M-b=0.9 M-J, and a radius of R-b=1.3 R-J, with a planetary density of 0.477 g cm(-3). TOI-2485 b has an orbital period of P-b=11.2 days, a mass of M-b=2.4 M-J, and a radius of R-b=1.1 R-J with a density of 2.36 g cm(-3). Conclusions. With the current parameters, the migration history for TOI-2420 b and TOI-2485 b is unclear: Scenarios of a high-eccentricity migration cannot be ruled out, and the characteristics of TOI-2485 b even support this scenario.
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    NGTS-11 b (TOI-1847 b): A Transiting Warm Saturn Recovered from a TESS Single-transit Event
    (2020) Gill, Samuel; Wheatley, Peter J.; Cooke, Benjamin F.; Jordan, Andres; Nielsen, Louise D.; Bayliss, Daniel; Anderson, David R.; Vines, Jose, I; Lendl, Monika; Acton, Jack S.; Armstrong, David J.; Bouchy, Francois; Brahm, Rafael; Bryant, Edward M.; Burleigh, Matthew R.; Casewell, Sarah L.; Eigmueller, Philipp; Espinoza, Nestor; Gillen, Edward; Goad, Michael R.; Grieves, Nolan; Gunther, Maximilian N.; Henning, Thomas; Hobson, Melissa J.; Hogan, Aleisha; Jenkins, James S.; McCormac, James; Moyano, Maximiliano; Osborn, Hugh P.; Pollacco, Don; Queloz, Didier; Rauer, Heike; Raynard, Liam; Rojas, Felipe; Sarkis, Paula; Smith, Alexis M. S.; Pinto, Marcelo Tala; Tilbrook, Rosanna H.; Udry, Stephane; Watson, Christopher A.; West, Richard G.
    We report the discovery of NGTS-11 b (=TOI-1847b), a transiting Saturn in a 35.46 day orbit around a mid K-type star (T-eff = 5050 +/- 80 K). We initially identified the system from a single-transit event in a TESS full-frame image light curve. Following 79 nights of photometric monitoring with an NGTS telescope, we observed a second full transit of NGTS-11 b approximately one year after the TESS single-transit event. The NGTS transit confirmed the parameters of the transit signal and restricted the orbital period to a set of 13 discrete periods. We combined our transit detections with precise radial-velocity measurements to determine the true orbital period and measure the mass of the planet. We find NGTS-11 b has a radius of 0.817 +/-(0.028)(0.032) R-Jup, a mass of 0.344 +/-(0.092)(0.073) M-Jup, and an equilibrium temperature of just 435 +/-(34)(32) K, making it one of the coolest known transiting gas giants. NGTS-11 b is the first exoplanet to be discovered after being initially identified as a TESS single-transit event, and its discovery highlights the power of intense photometric monitoring in recovering longer-period transiting exoplanets from single-transit events.
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    Orbital Alignment of the Eccentric Warm Jupiter TOI-677 b
    (2023) Sedaghati, Elyar; Jordan, Andres; Brahm, Rafael; Munoz, Diego J.; Petrovich, Cristobal; Hobson, Melissa J.
    Warm Jupiters lay out an excellent laboratory for testing models of planet formation and migration. Their separation from the host star makes tidal reprocessing of their orbits ineffective, which preserves the orbital architectures that result from the planet-forming process. Among the measurable properties, the orbital inclination with respect to the stellar rotational axis, stands out as a crucial diagnostic for understanding the migration mechanisms behind the origin of close-in planets. Observational limitations have made the procurement of spin-orbit measurements heavily biased toward hot Jupiter systems. In recent years, however, high-precision spectroscopy has begun to provide obliquity measurements for planets well into the warm Jupiter regime. In this study, we present Rossiter-McLaughlin (RM) measurements of the projected obliquity angle for the warm Jupiter TOI-677 b using ESPRESSO at the VLT. TOI-677 b exhibits an extreme degree of alignment (lambda = 0.3 +/- 1.3 deg), which is particularly puzzling given its significant eccentricity (e approximate to 0.45). TOI-677 b thus joins a growing class of close-in giants that exhibit large eccentricities and low spin-orbit angles, which is a configuration not predicted by existing models. We also present the detection of a candidate outer brown dwarf companion on an eccentric, wide orbit (e approximate to 0.4 and P approximate to 13 yr). Using simple estimates, we show that this companion is unlikely to be the cause of the unusual orbit of TOI-677 b. Therefore, it is essential that future efforts prioritize the acquisition of RM measurements for warm Jupiters.
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    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.
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    Resolving the planetesimal belt of HR 8799 with ALMA
    (2016) Haworth-Booth, Mark; Jordán Colzani, Andrés Cristóbal; Casassus, Simon; Hales, Antonio S.; Dent, William R. F.; Faramaz, Virginie; Matrà, Luca; Barkats, Denis; Brahm, Rafael; Cuadra Stipetich, Jorge Rodrigo