An unique telescope becomes part of the option
Repeated observations of the dips in the stars brightness provide precise measurements of the worlds orbital period around the star, and the depth of the transit permits researchers to identify the worlds size. When integrated with planet mass estimates from other techniques, such as using radial velocity measurements, the planet density can be determined.
Planet TOI-2257 b was at first determined by information from NASAs Transiting Exoplanet Survey Satellite TESS area telescope. The small star was observed for an overall of 4 months, however the spaces between observations implied that it was not clear whether the decrease in brightness might be explained by the transit of a planet with an orbit of 176, 88, 59, 44, or 35 days.
The SAINT-EX Observatory is a totally robotic facility hosting a 1-metre telescope based in Mexico. Credit: Institute of Astronomy, UNAM/ E. Cadena
Observation of the star with the Las Cumbres Observatory Global Telescope subsequently dismissed the possibility that a world with a 59-day orbital duration was triggering the drop in brightness. “Next, we wished to find out if the 35-day orbital period could be possible,” explains Nicole Schanche.
The Mexico-based SAINT-EX telescope, co-operated by the CSH and the NCCR PlanetS, is purpose-built to study red overshadows and their planets in more information. SAINT-EX observed a partial transit of TOI-2257 b and was able to validate the exoplanets precise orbital period around its star, 35 days.
A temperate planet with an irregular orbit
With its 35-day orbital duration, TOI-2257 b orbits the host star at a range where liquid water is possible in the world, and therefore conditions favorable for the development of life could exist. Worlds in this so-called “habitable zone” near a little red dwarf star are easier to study because they have much shorter orbital periods and can therefore be observed more typically. The radius of TOI-2257 b (2.2 times larger than Earths) suggests that the world is rather gaseous, with high air pressure not favorable to life.
TESS target pixel files of Sectors 14, 20, 21, and 26 that observed TOI-2257, produced by means of tpfplotter (Aller et al. 2020). The apertures used to extract the photometry by the SPOC pipeline are shown as red shaded areas. The Gaia DR2 brochure (Gaia Collaboration 2018) is over-plotted, with all sources of approximately 6 magnitudes on the other hand with TOI-2257 revealed as red circles. We note that the symbol size scales with the magnitude contrast. While the star is relatively separated, there is a percentage of contamination from outdoors sources, ranging from 2– 5% of the overall flux. Credit: DOI: 10.1051/ 0004-6361/2021 42280.
” We discovered that TOI-2257 b does not have a circular, concentric orbit,” discusses Nicole Schanche. In truth, it is the most eccentric world orbiting a cool star ever discovered. “In terms of possible habitability, this is bad news,” Nicole Schanche continues. “While the planets typical temperature is comfortable, it differs from -80 ° C to about 100 ° C depending on where in its orbit the planet is, far from or near the star.” A possible description for this unexpected orbit is that additional out in the system a giant world is disturbing the orbit and hiding of TOI 2257 b. Further observations measuring the radial speed of the star will help validate the eccentricity and look for possible additional worlds that could not be observed in transit.
Prospect for observation with JWST.
The James Webb Space Telescope (JWST), which effectively launched on December 25, will reinvent research into exoplanet atmospheres. In order to focus on great candidates for observations with the JWST, a transmission spectroscopy metric (TSM) was developed that rates different system residential or commercial properties. TOI-2257 b is well positioned with regard to TSM and is among the most appealing sub-Neptune targets for additional observations. “In specific, the world might be studied for signs of features such as water vapor in the atmosphere,” Nicole Schanche concludes.
Reference: “TOI-2257 b: An extremely eccentric long-period sub-Neptune transiting a nearby M dwarf” by N. Schanche, F. J. Pozuelos, M. N. Günther, R. D. Wells, A. J. Burgasser, P. Chinchilla, L. Delrez, E. Ducrot, L. J. Garcia, Y. Gómez Maqueo Chew, E. Jofré, B. V. Rackham, D. Sebastian, K. G. Stassun, D. Stern, M. Timmermans, K. Barkaoui, A. Belinski, Z. Benkhaldoun, W. Benz, A. Bieryla, F. Bouchy, A. Burdanov, D. Charbonneau, J. L. Christiansen, K. A. Collins, B.-O. Demory, M. Dévora-Pajares, J. de Wit, D. Dragomir, G. Dransfield, E. Furlan, M. Ghachoui, M. Gillon, C. Gnilka, M. A. Gómez-Muñoz, N. Guerrero, M. Harris, K. Heng, C. E. Henze, K. Hesse, S. B. Howell, E. Jehin, J. Jenkins, E. L. N. Jensen, M. Kunimoto, D. W. Latham, K. Lester, K. K. McLeod, I. Mireles, C. A. Murray, P. Niraula, P. P. Pedersen, D. Queloz, E. V. Quintana, G. Ricker, A. Rudat, L. Sabin, B. Safonov, U. Schroffenegger, N. Scott, S. Seager, I. Strakhov, A. H. M. J. Triaud, R. Vanderspek, M. Vezie and J. Winn, 7 January 2022, Astronomy & & Astrophysics.DOI: 10.1051/ 0004-6361/2021 42280.
The distance between an exoplanet and its star is a crucial element in its detection: the closer a planet is to its host star, the higher the possibility that it can be spotted.
Repeated observations of the dips in the stars brightness give precise measurements of the worlds orbital period around the star, and the depth of the transit allows researchers to figure out the worlds diameter. When combined with world mass estimates from other techniques, such as utilizing radial velocity measurements, the planet density can be calculated.
The Mexico-based SAINT-EX telescope, co-operated by the CSH and the NCCR PlanetS, is purpose-built to study red overshadows and their worlds in more information. A possible description for this unexpected orbit is that more out in the system a giant world is lurking and disturbing the orbit of TOI 2257 b. Further observations measuring the radial velocity of the star will assist confirm the eccentricity and search for possible extra planets that might not be observed in transit.
Artists impression of planets orbiting a red dwarf. Credit: Mark Garlick
Led by the University of Bern, a global research study team has discovered a sub-Neptune exoplanet orbiting a red dwarf star. The discovery was likewise made thanks to observations performed by the SAINT-EX observatory in Mexico. SAINT-EX is run by a consortium including the Center for Space and Habitability (CSH) at the University of Bern and the National Center of Competence in Research NCCR PlanetS.
” Red overshadows” are small stars and hence much cooler than our Sun. Around stars like these, liquid water is possible on planets much more detailed to the star than in our planetary system. The distance between an exoplanet and its star is a vital consider its detection: the closer a world is to its host star, the higher the likelihood that it can be discovered.
In a study just recently released in the journal Astronomy & & Astrophysics, scientists led by Dr. Nicole Schanche of the Center for Space and Habitability CSH of the University of Bern report the discovery of the exoplanet TOI-2257 b orbiting a close-by red dwarf. Nicole Schanche is likewise a member of the National Center of Competence in Research PlanetS, which the University of Bern runs together with the University of Geneva.
