11 research outputs found
TOI-2084 b and TOI-4184 b: two new sub-Neptunes around M dwarf stars
We present the discovery and validation of two TESS exoplanets orbiting
nearby M dwarfs: TOI-2084b, and TOI-4184b. We characterized the host stars by
combining spectra from Shane/Kast and Magellan/FIRE, SED (Spectral Energy
Distribution) analysis, and stellar evolutionary models. In addition, we used
Gemini-South/Zorro & -North/Alopeke high-resolution imaging, archival science
images, and statistical validation packages to support the planetary
interpretation. We performed a global analysis of multi-colour photometric data
from TESS and ground-based facilities in order to derive the stellar and
planetary physical parameters for each system. We find that TOI-2084b and
TOI-4184b are sub-Neptune-sized planets with radii of Rp = 2.47 +/- 0.13R_Earth
and Rp = 2.43 +/- 0.21R_Earth, respectively. TOI-2084b completes an orbit
around its host star every 6.08 days, has an equilibrium temperature of T_eq =
527 +/- 8K and an irradiation of S_p = 12.8 +/- 0.8 S_Earth. Its host star is a
dwarf of spectral M2.0 +/- 0.5 at a distance of 114pc with an effective
temperature of T_eff = 3550 +/- 50 K, and has a wide, co-moving M8 companion at
a projected separation of 1400 au. TOI-4184b orbits around an M5.0 +/- 0.5 type
dwarf star (Kmag = 11.87) each 4.9 days, and has an equilibrium temperature of
T_eq = 412 +/- 8 K and an irradiation of S_p = 4.8 +/- 0.4 S_Earth. TOI-4184 is
a metal poor star ([Fe/H] = -0.27 +/- 0.09 dex) at a distance of 69 pc with an
effective temperature of T_eff = 3225 +/- 75 K. Both planets are located at the
edge of the sub-Jovian desert in the radius-period plane. The combination of
the small size and the large infrared brightness of their host stars make these
new planets promising targets for future atmospheric exploration with JWST.Comment: Accepted for publication in A&
TOI-2084 b and TOI-4184 b:two new sub-Neptunes around M dwarf stars
Funding: The research leading to these results has received funding from the ARC grant for Concerted Research Actions, financed by the Wallonia-Brussels Federation. This research is in part funded by the European Unionâs Horizon 2020 research and innovation program (grants agreements n⊠803193/BEBOP), and from the Science and Technology Facilities Council (STFC; grant n⊠ST/S00193X/1). U.G.J. gratefully acknowledges support from tthe European Union H2020-MSCA-ITN-2019 under grant No. 860470 (CHAMELEON). We acknowledge funding from the European Research Council under the ERC Grant Agreement n. 337591-ExTrA.We present the discovery and validation of two TESS exoplanets orbiting nearby M dwarfs: TOI-2084 b, and TOI-4184b. We characterized the host stars by combining spectra from Shane/Kast and Magellan/FIRE, spectral energy distribution analysis, and stellar evolutionary models. In addition, we used Gemini-South/Zorro & -North/Alopeke high-resolution imaging, archival science images, and statistical validation packages to support the planetary interpretation. We performed a global analysis of multi-colour photometric data from TESS and ground-based facilities in order to derive the stellar and planetary physical parameters for each system. We find that TOI-2084 band TOI-4184 bare sub-Neptune-sized planets with radii of Rp = 2.47 ± 0.13Râ and Rp = 2.43 ± 0.21 Râ, respectively. TOI-2084 b completes an orbit around its host star every 6.08 days, has an equilibrium temperature of Teq = 527 ± 8 K and an irradiation of Sp = 12.8 ± 0.8 Sâ. Its host star is a dwarf of spectral M2.0 ± 0.5 at a distance of 114 pc with an effective temperature of Teff = 3550 ± 50 K, and has a wide, co-moving M8 companion at a projected separation of 1400 au. TOI-4184 b orbits around an M5.0 ± 0.5 type dwarf star (Kmag = 11.87) each 4.9 days, and has an equilibrium temperature of Teq = 412 ± 8 K and an irradiation of Sp = 4.8 ± 0.4 Sâ. TOI-4184 is a metal poor star ([Fe/H] = â0.27 ± 0.09 dex) at a distance of 69 pc with an effective temperature of Teff = 3225 ± 75 K. Both planets are located at the edge of the sub-Jovian desert in the radius-period plane. The combination of the small size and the large infrared brightness of their host stars make these new planets promising targets for future atmospheric exploration with JWST.Publisher PDFPeer reviewe
Constraints on the structure and seasonal variations of Triton's atmosphere from the 5 October 2017 stellar occultation and previous observations
Context. A stellar occultation by Neptune's main satellite, Triton, was observed on 5 October 2017 from Europe, North Africa, and the USA. We derived 90 light curves from this event, 42 of which yielded a central flash detection.
Aims. We aimed at constraining Triton's atmospheric structure and the seasonal variations of its atmospheric pressure since the Voyager 2 epoch (1989). We also derived the shape of the lower atmosphere from central flash analysis.
Methods. We used Abel inversions and direct ray-tracing code to provide the density, pressure, and temperature profiles in the altitude range similar to 8 km to similar to 190 km, corresponding to pressure levels from 9 mu bar down to a few nanobars.
Results. (i) A pressure of 1.18 +/- 0.03 mu bar is found at a reference radius of 1400 km (47 km altitude). (ii) A new analysis of the Voyager 2 radio science occultation shows that this is consistent with an extrapolation of pressure down to the surface pressure obtained in 1989. (iii) A survey of occultations obtained between 1989 and 2017 suggests that an enhancement in surface pressure as reported during the 1990s might be real, but debatable, due to very few high S/N light curves and data accessible for reanalysis. The volatile transport model analysed supports a moderate increase in surface pressure, with a maximum value around 2005-2015 no higher than 23 mu bar. The pressures observed in 1995-1997 and 2017 appear mutually inconsistent with the volatile transport model presented here. (iv) The central flash structure does not show evidence of an atmospheric distortion. We find an upper limit of 0.0011 for the apparent oblateness of the atmosphere near the 8 km altitude.J.M.O. acknowledges financial support from the Portuguese Foundation for Science and Technology (FCT) and the European Social Fund (ESF) through the PhD grant SFRH/BD/131700/2017. The work leading to these results has received funding from the European Research Council under the European Community's H2020 2014-2021 ERC grant Agreement nffi 669416 "Lucky Star". We thank S. Para who supported some travels to observe the 5 October 2017 occultation. T.B. was supported for this research by an appointment to the National Aeronautics and Space Administration (NASA) Post-Doctoral Program at the Ames Research Center administered by Universities Space Research Association (USRA) through a contract with NASA. We acknowledge useful exchanges with Mark Gurwell on the ALMA CO observations. This work has made use of data from the European Space Agency (ESA) mission Gaia (https://www.cosmos.esa.int/gaia), processed by the Gaia Data Processing and Analysis Consortium (DPAC, https://www.cosmos.esa.int/web/gaia/dpac/consortium).Funding for the DPAC has been provided by national institutions, in particular the institutions participating in the Gaia Multilateral Agreement. J.L.O., P.S.-S., N.M. and R.D. acknowledge financial support from the State Agency for Research of the Spanish MCIU through the "Center of Excellence Severo Ochoa" award to the Instituto de Astrofisica de Andalucia (SEV-2017-0709), they also acknowledge the financial support by the Spanish grant AYA-2017-84637-R and the Proyecto de Excelencia de la Junta de Andalucia J.A. 2012-FQM1776. The research leading to these results has received funding from the European Union's Horizon 2020 Research and Innovation Programme, under Grant Agreement no. 687378, as part of the project "Small Bodies Near and Far" (SBNAF). P.S.-S. acknowledges financial support by the Spanish grant AYA-RTI2018-098657-J-I00 "LEO-SBNAF". The work was partially based on observations made at the Laboratorio Nacional de Astrofisica (LNA), Itajuba-MG, Brazil. The following authors acknowledge the respective CNPq grants: F.B.-R. 309578/2017-5; R.V.-M. 304544/2017-5, 401903/2016-8; J.I.B.C. 308150/2016-3 and 305917/2019-6; M.A. 427700/20183, 310683/2017-3, 473002/2013-2. This study was financed in part by the Coordenacao de Aperfeicoamento de Pessoal de Nivel Superior -Brasil (CAPES) -Finance Code 001 and the National Institute of Science and Technology of the e-Universe project (INCT do e-Universo, CNPq grant 465376/2014-2). G.B.R. acknowledges CAPES-FAPERJ/PAPDRJ grant E26/203.173/2016 and CAPES-PRINT/UNESP grant 88887.571156/2020-00, M.A. FAPERJ grant E26/111.488/2013 and A.R.G.Jr. FAPESP grant 2018/11239-8. B.E.M. thanks CNPq 150612/2020-6 and CAPES/Cofecub-394/2016-05 grants. Part of the photometric data used in this study were collected in the frame of the photometric observations with the robotic and remotely controlled telescope at the University of Athens Observatory (UOAO; Gazeas 2016). The 2.3 m Aristarchos telescope is operated on Helmos Observatory by the Institute for Astronomy, Astrophysics, Space Applications and Remote Sensing of the National Observatory of Athens. Observations with the 2.3 m Aristarchos telescope were carried out under OPTICON programme. This project has received funding from the European Union's Horizon 2020 research and innovation programme under grant agreement No 730890. This material reflects only the authors views and the Commission is not liable for any use that may be made of the information contained therein. The 1.
2m Kryoneri telescope is operated by the Institute for Astronomy, Astrophysics, Space Applications and Remote Sensing of the National Observatory of Athens. The Astronomical Observatory of the Autonomous Region of the Aosta Valley (OAVdA) is managed by the Fondazione Clement Fillietroz-ONLUS, which is supported by the Regional Government of the Aosta Valley, the Town Municipality of Nus and the "Unite des Communes valdotaines Mont-Emilius". The 0.81 m Main Telescope at the OAVdA was upgraded thanks to a Shoemaker NEO Grant 2013 from The Planetary Society. D.C. and J.M.C. acknowledge funds from a 2017 'Research and Education' grant from Fondazione CRT-Cassa di Risparmio di Torino. P.M. acknowledges support from the Portuguese Fundacao para a Ciencia e a Tecnologia ref. PTDC/FISAST/29942/2017 through national funds and by FEDER through COMPETE 2020 (ref. POCI010145 FEDER007672). F.J. acknowledges Jean Luc Plouvier for his help. S.J.F. and C.A. would like to thank the UCL student support observers: Helen Dai, Elise Darragh-Ford, Ross Dobson, Max Hipperson, Edward Kerr-Dineen, Isaac Langley, Emese Meder, Roman Gerasimov, Javier Sanjuan, and Manasvee Saraf. We are grateful to the CAHA, OSN and La Hita Observatory staffs. This research is partially based on observations collected at Centro Astronomico HispanoAleman (CAHA) at Calar Alto, operated jointly by Junta de Andalucia and Consejo Superior de Investigaciones Cientificas (IAA-CSIC). This research was also partially based on observation carried out at the Observatorio de Sierra Nevada (OSN) operated by Instituto de Astrofisica de Andalucia (CSIC). This article is also based on observations made with the Liverpool Telescope operated on the island of La Palma by Liverpool John Moores University in the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofisica de Canarias with financial support from the UK Science and Technology Facilities Council. Partially based on observations made with the Tx40 and Excalibur telescopes at the Observatorio Astrofisico de Javalambre in Teruel, a Spanish Infraestructura Cientifico-Tecnica Singular (ICTS) owned, managed and operated by the Centro de Estudios de Fisica del Cosmos de Aragon (CEFCA). Tx40 and Excalibur are funded with the Fondos de Inversiones de Teruel (FITE). A.R.R. would like to thank Gustavo Roman for the mechanical adaptation of the camera to the telescope to allow for the observation to be recorded. R.H., J.F.R., S.P.H. and A.S.L. have been supported by the Spanish projects AYA2015-65041P and PID2019-109467GB-100 (MINECO/FEDER, UE) and Grupos Gobierno Vasco IT1366-19. Our great thanks to Omar Hila and their collaborators in Atlas Golf Marrakech Observatory for providing access to the T60cm telescope. TRAPPIST is a project funded by the Belgian Fonds (National) de la Recherche Scientifique (F.R.S.-FNRS) under grant PDR T.0120.21. TRAPPIST-North is a project funded by the University of Liege, and performed in collaboration with Cadi Ayyad University of Marrakesh. E.J. is a FNRS Senior Research Associate
TESS discovery of a sub-Neptune orbiting a mid-M dwarf TOI-2136
peer reviewedWe 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 pc away with a radius of
, a mass of and an
effective temperature of . We estimate its stellar rotation
period to be 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 observations, and precise radial
velocities from CFHT/SPIRou. Our joint analysis reveals that the planet has a
radius of , and a mass measurement of $6.4\pm2.4\
M_{\oplus}$. The mass and radius of TOI2136b is consistent with a broad range
of compositions, from water-ice to gas-dominated worlds. TOI-2136b falls close
to the radius valley for low-mass stars predicted by the thermally driven
atmospheric mass loss models, making it an interesting target for future
studies of its interior structure and atmospheric properties
Constraints on the structure and seasonal variations of Tritonâs atmosphere from the 5 October 2017 stellar occultation and previous observationsâ
Context. A stellar occultation by Neptune's main satellite, Triton, was observed on 5 October 2017 from Europe, North Africa, and the USA. We derived 90 light curves from this event, 42 of which yielded a central flash detection. Aims. We aimed at constraining Triton's atmospheric structure and the seasonal variations of its atmospheric pressure since the Voyager 2 epoch (1989). We also derived the shape of the lower atmosphere from central flash analysis. Methods. We used Abel inversions and direct ray-tracing code to provide the density, pressure, and temperature profiles in the altitude range âŒ8 km to âŒ190 km, corresponding to pressure levels from 9 ÎŒbar down to a few nanobars. Results. (i) A pressure of 1.18 ± 0.03 ÎŒbar is found at a reference radius of 1400 km (47 km altitude). (ii) A new analysis of the Voyager 2 radio science occultation shows that this is consistent with an extrapolation of pressure down to the surface pressure obtained in 1989. (iii) A survey of occultations obtained between 1989 and 2017 suggests that an enhancement in surface pressure as reported during the 1990s might be real, but debatable, due to very few high S/N light curves and data accessible for reanalysis. The volatile transport model analysed supports a moderate increase in surface pressure, with a maximum value around 2005-2015 no higher than 23 ÎŒbar. The pressures observed in 1995-1997 and 2017 appear mutually inconsistent with the volatile transport model presented here. (iv) The central flash structure does not show evidence of an atmospheric distortion. We find an upper limit of 0.0011 for the apparent oblateness of the atmosphere near the 8 km altitude
TOI-2084 b and TOI-4184 b:two new sub-Neptunes around M dwarf stars
We present the discovery and validation of two TESS exoplanets orbiting nearby M dwarfs: TOI-2084 b, and TOI-4184b. We characterized the host stars by combining spectra from Shane/Kast and Magellan/FIRE, spectral energy distribution analysis, and stellar evolutionary models. In addition, we used Gemini-South/Zorro & -North/Alopeke high-resolution imaging, archival science images, and statistical validation packages to support the planetary interpretation. We performed a global analysis of multi-colour photometric data from TESS and ground-based facilities in order to derive the stellar and planetary physical parameters for each system. We find that TOI-2084 band TOI-4184 bare sub-Neptune-sized planets with radii of Rp = 2.47 ± 0.13Râ and Rp = 2.43 ± 0.21 Râ, respectively. TOI-2084 b completes an orbit around its host star every 6.08 days, has an equilibrium temperature of Teq = 527 ± 8 K and an irradiation of Sp = 12.8 ± 0.8 Sâ. Its host star is a dwarf of spectral M2.0 ± 0.5 at a distance of 114 pc with an effective temperature of Teff = 3550 ± 50 K, and has a wide, co-moving M8 companion at a projected separation of 1400 au. TOI-4184 b orbits around an M5.0 ± 0.5 type dwarf star (Kmag = 11.87) each 4.9 days, and has an equilibrium temperature of Teq = 412 ± 8 K and an irradiation of Sp = 4.8 ± 0.4 Sâ. TOI-4184 is a metal poor star ([Fe/H] = â0.27 ± 0.09 dex) at a distance of 69 pc with an effective temperature of Teff = 3225 ± 75 K. Both planets are located at the edge of the sub-Jovian desert in the radius-period plane. The combination of the small size and the large infrared brightness of their host stars make these new planets promising targets for future atmospheric exploration with JWST
TESS discovery of a sub-Neptune orbiting a mid-M dwarf TOI-2136
We present the discovery of TOI-2136 b, a sub-Neptune planet transiting a nearby M4.5V-type star every 7.85 days, identified through photometric measurements from the TESS mission. The host star is located 33 pc away with a radius of R* = 0.34 ± 0.02 Râ, a mass of 0.34 ± 0.02 Mâ and an effective temperature of 3342 ± 100 K. We estimate its stellar rotation period to be 75 ± 5 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 observations, and precise radial velocities from CFHT/SPIRou. Our joint analysis reveals that the planet has a radius of 2.20 ± 0.17 Râ and a mass of 6.4 ± 2.4 Mâ. The mass and radius of TOI-2136 b is consistent with a broad range of compositions, from water-ice to gas-dominated worlds. TOI-2136 b falls close to the radius valley for M dwarfs predicted by thermally driven atmospheric mass loss models, making it an interesting target for future studies of its interior structure and atmospheric properties
VizieR Online Data Catalog: Triton light curves from 05/10/2017 (Marques Oliveira+, 2022)
International audienceThe data provided features all light curves from the 5 October 2017 event. The names of the files are the same names, in lower caps and with no spaces, that are presented in Figures C.1 and C.2. The first column of all files is the time in seconds, starting on 5 October 2017 00:00:00 UTC. The second column of all files is the normalised flux, where the unocculted flux oscillates around 1. (2 data files)
Constraints on the structure and seasonal variations of Triton's atmosphere from the 5 October 2017 stellar occultation and previous observations
A stellar occultation by Neptune's main satellite, Triton, was observed on 5
October 2017 from Europe, North Africa, and the USA. We derived 90 light curves
from this event, 42 of which yielded a central flash detection.
We aimed at constraining Triton's atmospheric structure and the seasonal
variations of its atmospheric pressure since the Voyager 2 epoch (1989). We
also derived the shape of the lower atmosphere from central flash analysis. We
used Abel inversions and direct ray-tracing code to provide the density,
pressure, and temperature profiles in the altitude range 8 km to
190 km, corresponding to pressure levels from 9 {\mu}bar down to a few
nanobars.
Results. (i) A pressure of 1.180.03 {\mu}bar is found at a reference
radius of 1400 km (47 km altitude). (ii) A new analysis of the Voyager 2 radio
science occultation shows that this is consistent with an extrapolation of
pressure down to the surface pressure obtained in 1989. (iii) A survey of
occultations obtained between 1989 and 2017 suggests that an enhancement in
surface pressure as reported during the 1990s might be real, but debatable, due
to very few high S/N light curves and data accessible for reanalysis. The
volatile transport model analysed supports a moderate increase in surface
pressure, with a maximum value around 2005-2015 no higher than 23 {\mu}bar. The
pressures observed in 1995-1997 and 2017 appear mutually inconsistent with the
volatile transport model presented here. (iv) The central flash structure does
not show evidence of an atmospheric distortion. We find an upper limit of
0.0011 for the apparent oblateness of the atmosphere near the 8 km altitude.Comment: 52 pages, 26 figures in the main paper, 2 figures in appendix B, 9
figures in appendix C, 1 long table over 5 page