2023-04-19 18:14:50
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[EN VIDÉO] In video: The Tess satellite has just concluded its main mission NASA’s Tess satellite has just completed its primary objective at the end of…
On April 17, 2023, the now famous Encyclopedia of extrasolar planets mentions that 5,363 exoplanets are known from the noosphere. Several thousand of them have been discovered thanks to NASA’s Kepler space telescope. The method used for this with Kepler is that of planetary transit, that is to say that it consisted in highlighting a periodic drop in the luminous intensity of a star due to the passage between it and Kepler’s instruments. of an exoplanet.
Kepler no longer works and, even if we continue to discover exoplanets in the list of candidates in its observation archives, NASA launched almost 5 years ago a telescope to take over: Tess (Transiting Exoplanet Survey Satellite). The agency has also just put several videos online to celebrate the fifth anniversary of the start of Tess’ observations, recalling in passing in a press release that they were not limited to the discovery of potential exoterres in the habitability zone. .
Using her four cameras, Tess monitors large swaths of the sky called sectors for regarding a month at a time. Each sector measures 24 by 96 degrees — regarding as wide as a person’s hand at arm’s length and stretching from the horizon to the zenith. CCD cameras capture a total of 192 million pixels in each frame. During her main mission, Tess took one of these images every 30 minutes, but this torrent of data grew over time. Cameras now record each sector every 200 seconds. To obtain a fairly accurate French translation, click on the white rectangle at the bottom right. The English subtitles should then appear. Then click on the nut to the right of the rectangle, then on “Subtitles” and finally on “Translate automatically”. Choose “French”. © Nasa’s Goddard Space Flight Center/Scientific Visualization Studio
Exoterres but also eruptions of supermassive black holes
Indeed, of the more than 93% of the celestial vault observed by Tess, with 329 exoplanets already detected and thousands more awaiting confirmation (for example, by amateur astronomers on Earth using Unistellar eVscopes), there It is also possible to surprise and study transient phenomena such as supernovae and supermassive black hole eruptions.
We can cite in this regard the case of the active galaxy ESO 253-3 (see the video below) which is known to contain a supermassive black hole producing eruptions every 114 days. It is thought that this periodicity reflects the passage to the periapsis of a giant star then producing at that time, due to tidal forces, a transfer of mass from the star and which suddenly feeds the accretion disk surrounding the compact star which already contains regarding 78 million solar masses — that of the Milky Way only contains a little more than 4 million.
ESO 253-3 is a spiral galaxy containing two active regions and located regarding 570 million light-years from the Milky Way in the direction of the constellation of the Painter (in Latin Painter, -is, abbreviated as Pic), a faintly luminous southern hemisphere constellation. To obtain a fairly accurate French translation, click on the white rectangle at the bottom right. The English subtitles should then appear. Then click on the nut to the right of the rectangle, then on “Subtitles” and finally on “Translate automatically”. Choose “French”. © Nassa’s Goddard Space Flight Center/Scientific Visualization Studio
Among the significant exoplanet discoveries that can be credited to Tess (the main purpose of the telescope was to go in search of rocky exoplanets, if possible real potential exoterres, which are within a radius of only 300 light years of the Sun and therefore within range of the James-Webb telescope in an attempt to characterize possible atmospheres), we can cite the case of the planetary system discovered around a type M red dwarf, located 100 light-years from the Solar System, and which can therefore be observed in the constellation of Dorade.
This red dwarf, whose mass and size are regarding 40% of those of the Sun and with a surface temperature half lower, is called TOI 700 and the nearest exoplanet is called TOI 700 b, the others in alphabetical order. YOU is an abbreviation for Tess Objects of Interest in English, which can be translated as “Interesting object of Tess”. TOI 700 d and TOI 700 e have particularly caught the attention of astrophysicists because they are potentially exoterres. Futura had also written several articles regarding them from which we partially reproduce the content.
A presentation of the discovery of TOI 700 d by Tess using the method of planetary transits. To obtain a fairly accurate French translation, click on the white rectangle at the bottom right. The English subtitles should then appear. Then click on the nut to the right of the rectangle, then on “Subtitles” and finally on “Translate automatically”. Choose “French”. © NASA Goddard
Caution is advised with a potentially habitable exoplanet
So, since TOI 700 d is in the habitable zone, that means it is in an area where the heat from its star might allow liquid water to exist. But there is a long way to go, as explained to Futura and on several occasions by astrophysicist Franck Selsis, member of the CNRS and the Bordeaux Astrophysics Laboratory (LAB).
The atmosphere such an exoplanet may possess might make it as inhospitable as Venus; one can also wonder regarding its initial water content and the fact that it was able to retain enough to be really habitable. We also know that red dwarfs at the beginning of their existence are particularly angry and that the radiation they then emit is harmful not only to life but leads to an erosion of any atmospheres.
TOI 700 d, like its sisters TOI 700 b and TOI 700 c, is also in synchronous rotation, which means that these planets always present the same face to their star, like the Moon. The climatic models of this kind of exoplanets show that it is still possible that liquid water exists in certain regions because if they have atmospheres, currents can transport and distribute heat between the constantly diurnal and nocturnal faces. . Life might therefore exist on such planets.
It is of course too early to speculate on the exobiology that may exist on TOI 700 d. But it is certain that it will be a target of choice for the next generation of instruments, such as the James-Webb space telescope. They will be able to detect and begin to analyze the composition of the potential atmospheres of Tess TOIs, hoping to unearth convincing biosignatures, yet to be defined. And it will not be an easy task, as Franck Selsis had always explained to Futura in the case of the discovery of the Trappist 1 system.
A presentation of the discovery of TOI 700 e by Tess. To obtain a fairly accurate French translation, click on the white rectangle at the bottom right. The English subtitles should then appear. Then click on the nut to the right of the rectangle, then on “Subtitles” and finally on “Translate automatically”. Choose “French”. © NASA’s Goddard Space Flight Center/Scientific Visualization Studio
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