The multi-planet system TOI-421 -- A warm Neptune and a super puffy mini-Neptune transiting a G9 V star in a visual binary
Ilaria Carleo, Davide Gandolfi, Oscar Barragán, John H. Livingston, Carina M. Persson, Kristine W. F. Lam, Aline Vidotto, Michael B. Lund, Carolina Villarreal D… 展开作者
Ilaria Carleo, Davide Gandolfi, Oscar Barragán, John H. Livingston, Carina M. Persson, Kristine W. F. Lam, Aline Vidotto, Michael B. Lund, Carolina Villarreal D'Angelo, Karen A. Collins, Luca Fossati, Andrew W. Howard, Daria Kubyshkina, Rafael Brahm, Antonija Oklopčić, Paul Mollière, Seth Redfield, Luisa Maria Serrano, Fei Dai, Malcolm Fridlund, Francesco Borsa, Judith Korth, Massimiliano Esposito, Matías R. Díaz, Louise Dyregaard Nielsen, Coel Hellier, Savita Mathur, Hans J. Deeg, Artie P. Hatzes, Serena Benatti, Florian Rodler, Javier Alarcon, Lorenzo Spina, Ângela R. G. Santos, Iskra Georgieva, Rafael A. García, Lucía González-Cuesta, George R. Ricker, Roland Vanderspek, David W. Latham, Sara Seager, Joshua N. Winn, Jon M. Jenkins, Simon Albrecht, Natalie M. Batalha, Corey Beard, Patricia T. Boyd, François Bouchy, Jennifer A. Burt, R. Paul Butler, Juan Cabrera, Ashley Chontos, David Ciardi, William D. Cochran, Kevin I. Collins, Jeffrey D. Crane, Ian Crossfield, Szilard Csizmadia, Diana Dragomir, Courtney Dressing, Philipp Eigmüller, Michael Endl, Anders Erikson, Nestor Espinoza, Michael Fausnaugh, Fabo Feng, Erin Flowers, Benjamin Fulton, Erica J. Gonzales, Nolan Grieves, Sascha Grziwa, Eike W. Guenther, Natalia M. Guerrero, Thomas Henning, Diego Hidalgo, Teruyuki Hirano, Maria Hjorth, Daniel Huber, Howard Isaacson, Matias Jones, Andrés Jordán, Petr Kabáth, Stephen R. Kane, Emil Knudstrup, Jack Lubin, Rafael Luque, Ismael Mireles, Norio Narita, David Nespral, Prajwal Niraula, Grzegorz Nowak, Enric Palle, Martin Pätzold, Erik A Petigura, Jorge Prieto-Arranz, Heike Rauer, Paul Robertson, Mark E. Rose, Arpita Roy, Paula Sarkis, Joshua E. Schlieder, Damien Ségransan, Stephen Shectman, Marek Skarka, Alexis M. S. Smith, Jeffrey C. Smith, Keivan Stassun, Johanna Teske, Joseph D. Twicken, Vincent Van Eylen, Sharon Wang, Lauren M. Weiss, Aurélien Wyttenbach
We report the discovery of a warm Neptune and a hot sub-Neptune transiting TOI-421 (BD-14 1137, TIC 94986319), a bright (V=9.9) G9 dwarf star in a visual binary system observed by the TESS space mission in Sectors 5 and 6. We performed ground-based follow-up observations -- comprised of LCOGT transit photometry, NIRC2 adaptive optics imaging, and FIES, CORALIE, HARPS, HIRES, and PFS high-precision Doppler measurements -- and confirmed the planetary nature of the 16-day transiting candidate announced by the TESS team. We discovered an additional radial velocity signal with a period of 5 days induced by the presence of a second planet in the system, which we also found to transit its host star. We found that the inner mini-Neptune, TOI-421b, has an orbital period of Pb =5.19672 +- 0.00049 days, a mass of Mb = 7.17 +- 0.66 Mearth and a radius of Rb = 2.68+0.19-0.18 Rearth, whereas the outer warm Neptune, TOI-421 c, has a period of Pc =16.06819 +- 0.00035 days, a mass of Mc = 16.42+1.06-1.04 Mearth, a radius of Rc = 5.09+0.16-0.15 Rearth and a density of rho_c =0.685+0.080-0.072 g cm-3 . With its characteristics the inner planet (rho_b=2.05+0.52-0.41 g cm-3) is placed in the intriguing class of the super-puffy mini-Neptunes. TOI-421b and TOI-421c are found to be well suitable for atmospheric characterization. Our atmospheric simulations predict significant Ly-alpha transit absorption, due to strong hydrogen escape in both planets, and the presence of detectable CH_4 in the atmosphere of TOI-421c if equilibrium chemistry is assumed.
We report the discovery and validation of two TESS exoplanets orbiting faint M dwarfs: TOI-4479b and TOI-2081b. We have jointly analyzed space (TESS mission) and ground based (MuSCAT2, MuSCAT3 and SINISTRO instruments) lightcurves using our multi-color photometry transit analysis pipeline. This allowed us to compute contamination limits for both candidates and validate them as planet-sized companions. We found TOI-4479b to be a sub-Neptune-sized planet ($R_{p}=2.82^{+0.65}_{-0.63}~\rm R_{\oplus}$) and TOI-2081b to be a super-Earth-sized planet ($R_{p}=2.04^{+0.50}_{-0.54}~\rm R_{\oplus}$). Fur…
TESS is revolutionising the search for planets orbiting bright and nearby stars. In sectors 3 and 4, TESS observed TOI-402 (TIC-120896927), a bright V=9.1 K1 dwarf also known as HD 15337, and found two transiting signals with period of 4.76 and 17.18 days and radius of 1.90 and 2.21\,\Rearth. This star was observed as part of the radial-velocity search for planets using the HARPS spectrometer, and 85 precise radial-velocity measurements were obtained over a period of 14 years. In this paper, we analyse the HARPS radial-velocity measurements in hand to confirm the planetary nature of these two …
We confirm the planetary nature of TOI-1728b using a combination of ground-based photometry, near-infrared Doppler velocimetry and spectroscopy with the Habitable-zone Planet Finder.TOI-1728 is an old, inactive M0 star with \teff{} $= 3980^{+31}_{-32}$ K, which hosts a transiting super Neptune at an orbital period of $\sim$ 3.49 days. Joint fitting of the radial velocities and TESS and ground-based transits yields a planetary radius of $5.05_{-0.17}^{+0.16}$ R$_{\oplus}$, mass $26.78_{-5.13}^{+5.43}$ M$_{\oplus}$ and eccentricity $0.057_{-0.039}^{+0.054}$. We estimate the stellar properties, a…
We investigate the exoplanet candidate TOI-1422b, which was discovered by the TESS space telescope around the high proper-motion G2V star TOI-1422 ($V=10.6$ mag), 155pc away, with the primary goal of confirming its planetary nature and characterising its properties. We monitored TOI-1422 with the HARPS-N spectrograph for 1.5 years to precisely quantify its radial velocity variation. The radial velocity measurements are analyzed jointly with TESS photometry and we also check for blended companions through high-spatial resolution images using the AstraLux instrument. We estimate that the parent …
The Kepler and TESS missions revealed a remarkable abundance of sub-Neptune exoplanets. Despite this abundance, our understanding of the nature and compositional diversity of sub-Neptunes remains limited, to a large part because atmospheric studies via transmission spectroscopy almost exclusively aimed for low-density sub-Neptunes and even those were often affected by high-altitude clouds. The recent TESS discovery of the hot, dense TOI-824b ($2.93\,R_\oplus$ and $18.47\,M_\oplus$) opens a new window into sub-Neptune science by enabling the study of a dense sub-Neptune via secondary eclipses. …
We report the detection of a transiting hot Neptune exoplanet orbiting TOI-824 (SCR J1448-5735), a nearby (d = 64 pc) K4V star, using data from the \textit{Transiting Exoplanet Survey Satellite} (TESS). The newly discovered planet has a radius, $R_{\rm{p}}$ = 2.93 $\pm$ 0.20 R$_{\oplus}$, and an orbital period of 1.393 days. Radial velocity measurements using the Planet Finder Spectrograph (PFS) and the High Accuracy Radial velocity Planet Searcher (HARPS) spectrograph confirm the existence of the planet and we estimate its mass to be $M_{\rm{p}}$ = 18.47 $\pm$ 1.84 M$_{\oplus}$. The planet's …
We present the validation of a transiting low-density exoplanet orbiting the M2.5 dwarf TOI 620 discovered by the NASA TESS mission. We utilize photometric data from both TESS and ground-based follow-up observations to validate the ephemerides of the 5.09-day transiting signal and vet false positive scenarios. High-contrast imaging data are used to resolve the stellar host and exclude stellar companions at separations $\gtrsim 0.2''$. We obtain follow-up spectroscopy and corresponding precise radial velocities (RVs) with multiple PRV spectrographs to confirm the planetary nature of the transit…
Based on HARPS-N radial velocities (RVs) and TESS photometry, we present a full characterisation of the planetary system orbiting the late G dwarf TOI-561. After the identification of three transiting candidates by TESS, we discovered two additional external planets from RV analysis. RVs cannot confirm the outer TESS transiting candidate, which would also make the system dynamically unstable. We demonstrate that the two transits initially associated with this candidate are instead due to single transits of the two planets discovered using RVs. The four planets orbiting TOI-561 include an ultra…
TOI-333b: A Neptune Desert planet around a F7V star
Universidad de Chile（智利大学）；Centro de Astrofísica y Tecnologías Afines (CATA)（天文及相关技术中心）；Universidad Diego Portales（迭戈·波特莱斯大学）；Universidad Católica del Norte（北方天主教大学）；University of Naples Federico II（那不勒斯费德里科二世大学）；Vanderbilt University（范德堡大学）；Université de Liège（列日大学）；Queen Mary University of London（伦敦大学玛丽女王学院）
The Transiting Exoplanet Survey Satellite, TESS, is currently carrying out an all-sky search for small planets transiting bright stars. In the first year of the TESS survey, steady progress was made in achieving the mission's primary science goal of establishing bulk densities for 50 planets smaller than Neptune. During that year, TESS's observations were focused on the southern ecliptic hemisphere, resulting in the discovery of three mini-Neptunes orbiting the star TOI-125, a V=11.0 K0 dwarf. We present intensive HARPS radial velocity observations, yielding precise mass measurements for TOI-1…
Both young stars and multi-planet systems are primary objects that allow us to study, understand and constrain planetary formation and evolution theories. We validate the physical nature of two Neptune-type planets transiting TOI-942 (TYC 5909-319-1), a previously unacknowledged young star (50+30-20 Myr) observed by the TESS space mission in Sector 5. Thanks to a comprehensive stellar characterization, TESS light curve modelling and precise radial-velocity measurements, we validated the planetary nature of the TESS candidate and detect an additional transiting planet in the system on a larger …
The Neptune desert is a feature seen in the radius-mass-period plane, whereby a notable dearth of short period, Neptune-like planets is found. Here we report the {\it TESS} discovery of a new short-period planet in the Neptune desert, orbiting the G-type dwarf TYC\,8003-1117-1 (TOI-132). {\it TESS} photometry shows transit-like dips at the level of $\sim$1400 ppm occurring every $\sim$2.11 days. High-precision radial velocity follow-up with HARPS confirmed the planetary nature of the transit signal and provided a semi-amplitude radial velocity variation of $\sim$11.5 m s$^{-1}$, which, when co…
Mapping the orbital obliquity distribution of young planets is one avenue towards understanding mechanisms that sculpt the architectures of planetary systems. TOI-942 is a young field star, with an age of ~60 Myr, hosting a planetary system consisting of two transiting Neptune-sized planets in 4.3- and 10.1-day period orbits. We observed the spectroscopic transits of the inner Neptune TOI-942b to determine its projected orbital obliquity angle. Through two partial transits, we find the planet to be in a prograde orbit, with a projected obliquity angle of |lambda| = 1/+41-33 deg. In addition, i…
We investigate the potential for the James Webb Space Telescope (JWST) to detect and characterize the atmospheres of the sub-Neptunian exoplanets in the TOI-270 system. Sub-Neptunes are considered more likely to be water worlds than gas dwarfs. We model their atmospheres using three atmospheric compositions - two examples of hydrogen-dominated atmospheres and a water-dominated atmosphere. We then simulate the infrared transmission spectra of these atmospheres for JWST instrument modes optimized for transit observation of exoplanet atmospheres : NIRISS, NIRSpec and MIRI. We then predict the obs…
We report the detection and characterization of the transiting sub-Neptune TOI-1759 b, using photometric time-series from TESS and near infrared spectropolarimetric data from SPIRou on the CFHT. TOI-1759 b orbits a moderately active M0V star with an orbital period of $18.849975\pm0.000006$ d, and we measure a planetary radius and mass of $3.06\pm0.22$ R$_\oplus$ and $6.8\pm2.0$ M$_\oplus$. Radial velocities were extracted from the SPIRou spectra using both the CCF and the LBL methods, optimizing the velocity measurements in the near infrared domain. We analyzed the broadband SED of the star an…
[Abridged] We exploit the extreme radial velocity (RV) precision of the ultra-stable echelle spectrograph ESPRESSO on the VLT to unveil the physical properties of the transiting sub-Neptune TOI-130 b, uncovered by TESS orbiting the nearby, bright, late F-type star HD 5278 (TOI-130) with a period $P_{\rm b}=14.3$. We use 43 ESPRESSO high-resolution spectra and broad-band photometry information to derive accurate stellar atmospheric and physical parameters of HD 5278. We exploit the TESS light curve (LC) and spectroscopic diagnostics to gauge the impact of stellar activity on the ESPRESSO RVs. W…
We present the discovery of TOI-2136b, a sub-Neptune planet transiting every 7.85 days a nearby M4.5V-type star, identified through photometric measurements from the TESS mission. The host star is located $33$ pc away with a radius of $R_{\ast} = 0.34\pm0.02\ R_{\odot}$, a mass of $0.34\pm0.02\ M_{\odot}$ and an effective temperature of $\rm 3342\pm100\ K$. We estimate its stellar rotation period to be $75\pm5$ days based on archival long-term photometry. We confirm and characterize the planet based on a series of ground-based multi-wavelength photometry, high-angular-resolution imaging observ…
Sibling Sub-Neptunes Around Sibling M Dwarfs: TOI-521 and TOI-912
Instituto de Astrofísica de Canarias (IAC)（加那利群岛天体物理研究所）；Universidad de La Laguna (ULL)（拉古纳大学）；Instituto de Astrofísica de Andalucía (IAA-CSIC)（安达卢西亚天体物理研究所）；Hitotsubashi University（一桥大学）；Institut d’Estudis Espacials de Catalunya (IEEC)（加泰罗尼亚空间研究所）；Institut de Ciències de l’Espai (ICE, CSIC)（空间科学研究所）；Centro de Astrobiología (CSIC-INTA)（天体生物学中心）；Univ. Grenoble Alpes（格勒诺布尔阿尔卑斯大学）；Institute of Astronomy, Faculty of Physics, Astronomy and Informatics, Nicolaus Copernicu（尼古拉·哥白尼大学天文系，物理、天文与信息学院）
Spin-Orbit Alignment of Two Neptune-size Planets Younger than 500 Myr: TOI-560 b and TOI-5082 b
Institute for Astronomy, University of Hawaii（夏威夷大学天文研究所）；Department of Astronomy, California Institute of Technology（加州理工学院天文学系）；Jet Propulsion Laboratory, California Institute of Technology（加州理工学院喷气推进实验室）；Department of Astronomy, University of California Berkeley（加州大学伯克利分校天文学系）；Center for Computational Astrophysics, Flatiron Institute（西蒙斯基金会平顿研究所计算天体物理中心）；Korea Astronomy and Space Science Institute（韩国天文与空间科学研究院）；National Astronomical Observatories, Chinese Academy of Sciences（中国科学院国家天文台）；Department of Astronomy, Indiana University（印第安纳大学天文学系）
Transmission Spectrum of the Benchmark Temperate Exo-Neptune TOI-1231 b
School of Physics and Astronomy, Cardiff University（卡迪夫大学物理与天文学学院）；Institute of Astronomy, University of Cambridge（剑桥大学天文研究所）；Space Telescope Science Institute（太空望远镜科学研究所）；Space Science Institute（空间科学研究所）
We confirm the planetary nature of TOI-532b, using a combination of precise near-infrared radial velocities with the Habitable-zone Planet Finder, TESS light curves, ground based photometric follow-up, and high-contrast imaging. TOI-532 is a faint (J$\sim 11.5$) metal-rich M dwarf with Teff = $3957\pm69$ K and [Fe/H] = $0.38\pm0.04$; it hosts a transiting gaseous planet with a period of $\sim 2.3$ days. Joint fitting of the radial velocities with the TESS and ground-based transits reveal a planet with radius of $5.82\pm0.19$ R$_{\oplus}$, and a mass of $61.5_{-9.3}^{+9.7}$ M$_{\oplus}$. TOI-53…
We present the validation of two planets orbiting M dwarfs, TOI-1696b and TOI-2136b. Both planets are mini-Neptunes orbiting nearby stars, making them promising prospects for atmospheric characterization with the James Webb Space Telescope. We validated the planetary nature of both candidates using high contrast imaging, ground-based photometry, and near-infrared radial velocities. Adaptive Optics images were taken using the ShARCS camera on the 3 m Shane Telescope. Speckle images were taken using the NN-Explore Exoplanet Stellar Speckle Imager on the WIYN 3.5 m telescope. Radii and orbital ep…
JWST NIRSpec G395H Transmission Spectra of Two Similar Sub-Neptunes in the TOI-125 System
Johns Hopkins University（约翰斯·霍普金斯大学）；Space Telescope Science Institute（太空望远镜科学研究所）；University of Oxford（牛津大学）；Cavendish Laboratory, JJ Thomson Avenue, Cambridge CB3 0HE, UK（剑桥大学卡文迪许实验室）；University of California San Diego（加利福尼亚大学圣地亚哥分校）
TOI-2076 b is a sub-Neptune-sized planet ($R= 2.39 \pm 0.10 {R_\oplus}$) that transits a young ($204 \pm 50 {MYr}$) bright ($V = 9.2$) K-dwarf hosting a system of three transiting planets. Using spectroscopic observations 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 $λ=-3_{-15}^{+16\:\circ}$. Using the size of the star ($R=0.775 \pm0.015 {R_\odot}$), and the stellar rotation period ($P_{\mathrm{rot}}=7.27\pm0.23$ days), we estimate an obliquity of $ψ=18_{-9}^{+10\:\circ}$ ($ψ< 34^\circ$ at…
We use TESS, Spitzer, ground-based light curves and HARPS spectrograph radial velocity measurements to establish the physical properties of the transiting exoplanet candidate TOI-674b. We perform a joint fit of the light curves and radial velocity time series to measure the mass, radius, and orbital parameters of the candidate. We confirm and characterize TOI-674b, a low-density super-Neptune transiting a nearby M dwarf. The host star (TIC 158588995, $V = 14.2$ mag, $J = 10.3$ mag) is characterized by its M2V spectral type with $\mathrm{M}_\star=0.420\pm 0.010$ M$_\odot$, $\mathrm{R}_\star = 0…
TOI-270d is a temperate sub-Neptune discovered by the Transiting Exoplanet Survey Satellite (TESS) around a bright (J=9.1mag) M3V host star. With an approximate radius of 2RE and equilibrium temperature of 350K, TOI-270d is one of the most promising small exoplanets for atmospheric characterisation using transit spectroscopy. Here we present a primary transit observation of TOI-270d made with the Hubble Space Telescope (HST) Wide Field Camera 3 (WFC3) spectrograph across the 1.126-1.644 micron wavelength range, and a 95% credible upper limit of $8.2 \times 10^{-14}$ erg s$^{-1}$ cm$^{-2}$ A$^{…
We report observations of the recently discovered warm Neptune TOI-674 b (5.25 \rearth{}, 23.6 \mearth{}) with the Hubble Space Telescope's Wide Field Camera 3 instrument. TOI-674 b is in the Neptune desert, an observed paucity of Neptune-size exoplanets at short orbital periods. Planets in the desert are thought to have complex evolutionary histories due to photoevaporative mass loss or orbital migration, making identifying the constituents of their atmospheres critical to understanding their origins. We obtained near-infrared transmission spectroscopy of the planet's atmosphere with the G141…
Densities of small planets around the M dwarfs TOI-4336 A and TOI-4342 with ESPRESSO: Three sub-Neptunes, one super-Earth, and a Neptune-mass candidate
Observatoire de Genève, Département d’Astronomie, Université de Genève（日内瓦天文台，天文学系，日内瓦大学）；Institut Trottier de recherche sur les exoplanètes, Département de Physique, Université de Montréal（特罗蒂埃系外行星研究所，物理系，蒙特利尔大学）；Institute for Particle Physics and Astrophysics, ETH Zürich（粒子物理学与天体物理学研究所，苏黎世联邦理工学院）；Centro de Astrobiología (CAB), CSIC-INTA（天体生物学中心（CAB），西班牙国家研究委员会-国家航空航天技术研究所）；Instituto de Astrofísica e Ciências do Espaço, Universidade do Porto, CAUP（天体物理学与空间科学研究所，波尔图大学，CAUP）；Departamento de Matemática y Física Aplicadas, Universidad Católica de la Santísima Concepción（应用数学与物理系，天主教神圣启示大学）；Univ. Grenoble Alpes, CNRS, IPAG（格勒诺布尔阿尔卑斯大学，法国国家科学研究中心，IPAG）；Department of Physics and Astronomy, McMaster University（物理与天文学系，麦克马斯特大学）；Center for Astrophysics | Harvard & Smithsonian（天体物理中心，哈佛大学与史密森尼学会）
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 PFS break that de…
We report the discovery of an eccentric hot Neptune and a non-transiting outer planet around TOI-1272. We identified the eccentricity of the inner planet, with an orbital period of 3.3 d and $R_{\rm p,b} = 4.1 \pm 0.2$ $R_\oplus$, based on a mismatch between the observed transit duration and the expected duration for a circular orbit. Using ground-based radial velocity measurements from the HIRES instrument at the Keck Observatory, we measured the mass of TOI-1272b to be $M_{\rm p,b} = 25 \pm 2$ $M_\oplus$. We also confirmed a high eccentricity of $e_b = 0.34 \pm 0.06$, placing TOI-1272b among…
The two planetary systems TOI-942 and TOI-421 share many similar characteristics, apart from their ages (50~Myr and 9~Gyr). Each of the stars hosts two sub-Neptune-like planets at similar orbits and in similar mass ranges. In this paper, we aim to investigate whether the similarity of the host stars and the configuration of the planetary systems can be taken as proof that the two systems were formed and evolved in a similar way. In paper I of this series, we performed a comparative study of these two systems using 3D modeling of atmospheric escape and its interaction with the stellar wind, for…
The Hot Neptune Initiative (HONEI) III. An ultra-hot super Neptune orbiting the metal-rich subgiant star TOI-5646: the largest host for a desert dweller
University of Rome “Tor Vergata”（罗马第二大学）；INAF – Turin Astrophysical Observatory（意大利国家天体物理研究所都灵天文台）；Space Research Institute, Austrian Academy of Sciences（奥地利科学院空间研究所）；University of Bern（伯尔尼大学）；Leiden University（莱顿大学）；INAF – Astronomical Observatory of Rome（意大利国家天体物理研究所罗马天文台）
A Pair of Dynamically Interacting Sub-Neptunes Around TOI-6054
University of Wisconsin–Madison（威斯康星大学麦迪逊分校）；University of Kansas（堪萨斯大学）；Max-Planck-Institut für Astronomie（马克斯·普朗克天文学研究所）；Jet Propulsion Laboratory, California Institute of Technology（加州理工学院喷气推进实验室）；University of California, Irvine（加州大学尔湾分校）；Center for Astrophysics | Harvard & Smithsonian（哈佛与史密森尼天体物理中心）；NASA Exoplanet Science Institute-Caltech/IPAC（NASA系外行星科学研究所-加州理工/IPAC）；Sternberg Astronomical Institute, Lomonosov Moscow State University（莫斯科国立大学斯捷克列夫天文研究所）；NASA Ames Research Center（NASA艾姆斯研究中心）；Bay Area Environmental Research Institute（湾区环境研究所）
