MSGID: 1:317/3 6482ab0c   
   PID: hpt/lnx 1.9.0-cur 2019-01-08   
   TID: hpt/lnx 1.9.0-cur 2019-01-08   
    Elusive planets play 'hide and seek' with CHEOPS    
      
     Date:   
         June 8, 2023   
     Source:   
         University of Bern   
     Summary:   
         Astronomers have clearly identified the existence of four new   
         exoplanets.   
      
         The four mini-Neptunes are smaller and cooler, and more difficult   
         to find than the so-called Hot Jupiter exoplanets which have been   
         found in abundance.   
      
      
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   FULL STORY   
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   With the help of the CHEOPS space telescope an international team of   
   European astronomers managed to clearly identify the existence of four   
   new exoplanets.   
      
   The four mini-Neptunes are smaller and cooler, and more difficult to   
   find than the so-called Hot Jupiter exoplanets which have been found   
   in abundance. Two of the four resulting papers are led by researchers   
   from the University of Bern and the University of Geneva who are also   
   members of the National Centre of Competence in Research (NCCR) PlanetS.   
      
   CHEOPS is a joint mission by the European Space Agency (ESA)   
   and Switzerland, under the leadership of the University of Bern in   
   collaboration with the University of Geneva. Since its launch in December   
   2019, the extremely precise measurements of CHEOPS have contributed to   
   several key discoveries in the field of exoplanets.   
      
   NCCR PlanetS members Dr. Sole`ne Ulmer-Moll of the Universities of Bern   
   and Geneva, and Dr. Hugh Osborn of the University of Bern, exploited the   
   unique synergy of CHEOPS and the NASA satellite TESS, in order to detect   
   a series of elusive exoplanets. The planets, called TOI 5678 b and HIP   
   9618 c respectively, are the size of Neptune or slightly smaller with   
   4.9 and 3.4 Earth radii. The respective papers have just been published   
   in the journals Astronomy & AstrophysicsandMonthly Notices of the Royal   
   Astronomical Society. Publishing in the same journals,two other members of   
   the international team, Amy Tuson from the University of Cambridge (UK)   
   and Dr. Zolta'n Garai from the ELTE Gothard Astrophysical Observatory   
   (Hungary), used the same technique to identify two similar planets in   
   other systems.   
      
   The synergy of two satellites The CHEOPS satellite observes the luminosity   
   of stars in order to capture the slight dimming that occurs when, and   
   if, an orbiting planet happens to pass in front of its star from our   
   point of view. By searching for these dimming events, called "transits,"   
   scientists have been able to discover the majority of the thousands of   
   exoplanets known to orbit stars other than our Sun.   
      
   "NASA's TESS satellite excels at detecting the transits of exoplanets,   
   even for the most challenging small planets. However, it changes its   
   field of view every 27 days in order to scan rapidly most of the sky,   
   which prevents it from finding planets on longer orbital periods,"   
   explains Hugh Osborn. Still, the TESS satellite was able to observe   
   single transits around the stars TOI 5678 and HIP 9618. When returning   
   to the same field of view after two years, it could again observe similar   
   transits around the same stars. Despite these observations, it was still   
   not possible to conclude unequivocally to the presence of planets around   
   those stars as information was incomplete.   
      
   "This is where CHEOPS comes into play: Focusing on a single-star at   
   a time, CHEOPS is a follow-up mission which is perfect to continue   
   observing these stars to find the missing bits of information,"   
   complements Sole`ne Ulmer-Moll.   
      
   A lengthy game of "hide and seek" Suspecting the presence of exoplanets,   
   the CHEOPS team designed a method to avoid spending blindly precious   
   observing time in the hope to detect additional transits. They adopted   
   a targeted approach based on the very few clues the transits observed by   
   TESS provided. Based on this, Osborn developed a software which proposes   
   and prioritizes candidate periods for each planet. "We then play a sort   
   of 'hide and seek' game with the planets, using the CHEOPS satellite,"   
   as Osborn says.   
      
   "We point CHEOPS towards a target at a given time, and depending if we   
   observe a transit or not, we can eliminate some of the possibilities   
   and try again at another time until there is a unique solution for the   
   orbital period." It took five and four attempts respectively for the   
   scientists to clearly confirm the existence of the two exoplanets and   
   determine that TOI 5678 b has a period of 48 days, while HIP 9618 c has   
   a period of 52.5 days.   
      
   Ideal targets for the JWST The story does not end there for the   
   scientists. With the newly found constrained periods, they could turn to   
   ground-based observations using another technique called radial velocity,   
   which enabled the team to determine masses of respectively 20 and 7.5   
   Earth masses for TOI 5678 b and HIP 9618 c. With both the size and mass   
   of a planet, its density is known, and scientists can get an idea of what   
   it is made off. "For mini-Neptunes however, density is not enough, and   
   there are still a few hypotheses as for the composition of the planets:   
   they could either be rocky planets with a lot of gas, or planets rich in   
   water and with a very steamy atmosphere," explains Ulmer-Moll. "Since the   
   four newly discovered exoplanets are orbiting bright stars, it also makes   
   them targets of prime interest for the mission of the James Webb Space   
   Telescope JWST which might help to solve the riddle of their composition,"   
   Ulmer-Moll continues.   
      
   Most exoplanets atmospheres observed so far have been from Hot Jupiters,   
   which are very big and hot exoplanets orbiting close to their parent   
   star. "The four new planets which we detected have much more moderate   
   temperatures of 'only' 217 to 277-oC. These temperatures enable clouds   
   and molecules to survive, which would otherwise be destroyed by the   
   intense heat of Hot Jupiters. And they may potentially be detected by   
   the JWST," as Osborn explains. Smaller in size and with a longer orbital   
   period than Hot Jupiters, the four newly detected planets are a first   
   step towards the observation of transiting Earth-like planets.   
      
       * RELATED_TOPICS   
             o Space_&_Time   
                   # Extrasolar_Planets # Satellites # Pluto # Stars #   
                   Kuiper_Belt # NASA # Astronomy # Space_Exploration   
       * RELATED_TERMS   
             o Extrasolar_planet o Jupiter o Jupiter's_moons o Asteroid o   
             Saturn o Dysnomia_(moon_of_Eris) o Uranus'_natural_satellites   
             o Astronomy   
      
   ==========================================================================   
   Story Source: Materials provided by University_of_Bern. Note: Content   
   may be edited for style and length.   
      
      
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   Journal References:   
      1. H P Osborn, G Nowak, G He'brard, T Masseron, J Lillo-Box, E   
      Palle', A   
         Bekkelien, H-G Flore'n, P Guterman, A E Simon, V Adibekyan, A   
         Bieryla, L Borsato, A Brandeker, D R Ciardi, A Collier Cameron, K   
         A Collins, J A Egger, D Gandolfi, M J Hooton, D W Latham, M Lendl,   
         E C Matthews, A Tuson, S Ulmer-Moll, A Vanderburg, T G Wilson,   
         C Ziegler, Y Alibert, R Alonso, G Anglada, L Arnold, J Asquier,   
         D Barrado y Navascues, W Baumjohann, T Beck, A A Belinski,   
         W Benz, F Biondi, I Boisse, X Bonfils, C Broeg, L A Buchhave,   
         T Ba'rczy, S C C Barros, J Cabrera, C Cardona Guillen, I Carleo,   
         A Castro-Gonza'lez, S Charnoz, J Christiansen, P Cortes-Zuleta,   
         S Csizmadia, S Dalal, M B Davies, M Deleuil, X Delfosse, L Delrez,   
         B-O Demory, A B Dunlavey, D Ehrenreich, A Erikson, R B Fernandes,   
         A Fortier, T Forveille, L Fossati, M Fridlund, M Gillon, R F Goeke,   
         M V Goliguzova, E J Gonzales, M N Gu"nther, M Gu"del, N Heidari,   
         C E Henze, S Howell, S Hoyer, J I Frey, K G Isaak, J M Jenkins,   
         F Kiefer, L Kiss, J Korth, P F L Maxted, J Laskar, A Lecavelier   
         des Etangs, C Lovis, M B Lund, R Luque, D Magrin, J M Almenara, E   
         Martioli, M Mecina, J V Medina, D Moldovan, M Morales-Caldero'n,   
         G Morello, C Moutou, F Murgas, E L N Jensen, V Nascimbeni, G   
         Olofsson, R Ottensamer, I Pagano, G Peter, G Piotto, D Pollacco,   
         D Queloz, R Ragazzoni, N Rando, H Rauer, I Ribas, G Ricker, O D   
         S Demangeon, A M S Smith, N Santos, G Scandariato, S Seager, S   
         G Sousa, M Steller, G M Szabo', D Se'gransan, N Thomas, S Udry,   
         B Ulmer, V Van Grootel, R Vanderspek, N Walton, J N Winn. Two   
         warm Neptunes transiting HIP 9618 revealed by TESS and   
         Cheops. Monthly Notices of the Royal Astronomical Society, 2023;   
         523 (2): 3069 DOI: 10.1093/ mnras/stad1319   
      2. S. Ulmer-Moll, H. P. Osborn, A. Tuson, J. A. Egger, M. Lendl,   
      P. Maxted,   
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         Bonfanti, F. Bouchy, A. Brandeker, M. Fridlund, D. Gandolfi, C.   
      
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         T. G.   
      
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         Baumjohann, M. Beck, T. Beck, W. Benz, N. Billot, X. Bonfils,   
         L. Borsato, C. Broeg, T. Ba'rczy, J. Cabrera, S. Charnoz,   
         M. Cointepas, A. Collier Cameron, Sz. Csizmadia, P. E. Cubillos,   
         M. B. Davies, M. Deleuil, A.   
      
         Deline, L. Delrez, O. D. S. Demangeon, B.-O. Demory, X. Dumusque, D.   
      
         Ehrenreich, N. L. Eisner, A. Erikson, A. Fortier, L. Fossati,   
         M. Gillon, N. Grieves, M. Gu"del, J. Hagelberg, R. Helled, S. Hoyer,   
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         Grootel, J. Venturini, N. A. Walton. TOI-5678b: A 48-day transiting   
         Neptune-mass planet characterized with CHEOPS and HARPS. Astronomy &   
         Astrophysics, 2023; 674: A43 DOI: 10.1051/0004-6361/202245478   
      3. Z. Garai, H. P. Osborn, D. Gandolfi, A. Brandeker, S. G. Sousa,   
      M. Lendl,   
         A. Bekkelien, C. Broeg, A. Collier Cameron, J. A. Egger,   
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         A. Bonfanti, A.   
      
         Tuson, S. Ulmer-Moll, L. M. Serrano, L. Borsato, R. Alonso,   
         G. Anglada, J. Asquier, D. Barrado y Navascues, S. C. C. Barros,   
         T. Ba'rczy, W.   
      
         Baumjohann, M. Beck, T. Beck, W. Benz, N. Billot, F. Biondi,   
         X. Bonfils, M. Buder, J. Cabrera, V. Cessa, S. Charnoz,   
         Sz. Csizmadia, P. E.   
      
         Cubillos, M. B. Davies, M. Deleuil, O. D. S. Demangeon,   
         B.-O. Demory, D.   
      
         Ehrenreich, A. Erikson, V. Van Eylen, A. Fortier, M. Fridlund,   
         M. Gillon, V. Van Grootel, M. Gu"del, M. N. Gu"nther, S. Hoyer,   
         K. G. Isaak, L. L.   
      
         Kiss, M. H. Kristiansen, J. Laskar, A. Lecavelier des Etangs,   
         C. Lovis, A. Luntzer, D. Magrin, P. F. L. Maxted, C. Mordasini,   
         V. Nascimbeni, G.   
      
         Olofsson, R. Ottensamer, I. Pagano, E. Palle', G. Peter,   
         G. Piotto, D.   
      
         Pollacco, D. Queloz, R. Ragazzoni, N. Rando, H. Rauer, I. Ribas,   
         N. C.   
      
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         Steller, Gy. M. Szabo', N. Thomas, S. Udry, J. Venturini, N. Walton.   
      
         Refined parameters of the HD 22946 planetary system and the true   
         orbital period of planet d. Astronomy & Astrophysics, 2023; 674:   
         A44 DOI: 10.1051/0004-6361/202345943   
      4. A Tuson, D Queloz, H P Osborn, T G Wilson, M J Hooton, M Beck,   
      M Lendl, G   
         Olofsson, A Fortier, A Bonfanti, A Brandeker, L A Buchhave, A   
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         Giacalone, J Gomes da Silva, S B Howell, J A Patel, C M Persson,   
         L M Serrano, S G Sousa, S Ulmer-Moll, A Vanderburg, C Ziegler,   
         Y Alibert, R Alonso, G Anglada, T Ba'rczy, D Barrado Navascues,   
         S C C Barros, W Baumjohann, T Beck, W Benz, N Billot, X Bonfils,   
         L Borsato, C Broeg, J Cabrera, S Charnoz, D M Conti, Sz Csizmadia,   
         P E Cubillos, M B Davies, M Deleuil, L Delrez, O D S Demangeon,   
         B-O Demory, D Dragomir, C D Dressing, D Ehrenreich, A Erikson,   
         Z Essack, J Farinato, L Fossati, M Fridlund, E Furlan, H Gill, M   
         Gillon, C L Gnilka, E Gonzales, M Gu"del, M N Gu"nther, S Hoyer,   
         K G Isaak, J M Jenkins, L L Kiss, J Laskar, D W Latham, N Law,   
         A Lecavelier des Etangs, G Lo Curto, C Lovis, R Luque, D Magrin,   
         A W Mann, P F L Maxted, M Mayor, S McDermott, M Mecina, C Mordasini,   
         A Mortier, V Nascimbeni, R Ottensamer, I Pagano, E Palle', G Peter,   
         G Piotto, D Pollacco, T Pritchard, R Ragazzoni, N Rando, F Ratti,   
         H Rauer, I Ribas, G R Ricker, M Rieder, N C Santos, A B Savel,   
         G Scandariato, R P Schwarz, S Seager, D Se'gransan, A Shporer,   
         A E Simon, A M S Smith, M Steller, C Stockdale, Gy M Szabo', N   
         Thomas, G Torres, R Tronsgaard, S Udry, B Ulmer, V Van Grootel,   
         R Vanderspek, J Venturini, N A Walton, J N Winn, B Wohler. TESS   
         and CHEOPS discover two warm sub-Neptunes transiting the bright   
         K-dwarf HD 15906. Monthly Notices of the Royal Astronomical   
         Society, 2023; 523 (2): 3090 DOI: 10.1093/mnras/stad1369   
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   Link to news story:   
   https://www.sciencedaily.com/releases/2023/06/230608120947.htm   
      
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