Meddelelse
NGTS finder sjælden gaskæmpe ved M-dværg
31. oktober 2017
Den tredje gaskæmpe - en hot Jupiter - i kredsløb om en M-dværgstjerne[1] er fundet med Next Generation Transit Survey (NGTS) instrumentet på ESOs Paranal Observatory i det nordlige Chile. Stjernen har fået navnet NGTS-1 og planeten tilsvarende NGTS-1b. De to første varme gaskæmper var Kepler-45b og HATS-6b. NGTS-1b er den største og tungeste af de tre. Den har en radius på 130% og en masse på 80% af Jupiter i vores eget Solsystem. Danskbaseret exoplanetjæger er også begejstret.
NGTS består af et anlæg med 12 stk 20-centimeterteleskoper, som ser efter de små dyk i en stjernes lysstyrke, som kommer når en planet i kredsløb om stjernen passerer ind foran den (- en transit, svarende til en solformørkelse, men meget længere væk), og blokerer for noget af dens lys. Da først NGTS-1b var fundet, blev dens eksistens bekræftet med observationer fra ESOs La Sillaobservatorium: fotometriske observationer med instrumentet EulerCam på det schweiziske 1,2-meter Leonhard Euler Telescope og spektroskopiske observationer med instrumentet HARPS på ESOs 3,6-meter teleskop.
Små planeter er forholdsvis almindelige ved M-dværgstjerner, men det ser ud til at kæmper som NGTS-1b er sjældnere omkring denne type stjerner end de er omkring stjerner, som mere ligner Solen. Det er fint i tråd med de nuværende teorier for planetdannelse, men der er brug for flere observationer af M-dværge for at astronomerne kan få mere præcise tal. Anlægget NGTS er specielt opbygget for at få bedre data om planeter omkring M-dværgstjernerne, og da den type stjerner udgør omkring 75% af alle stjernerne i Mælkevejen, er studiet af dem vigtig for forståelsen af planeterne i hele galaksen.
Fremtiden lover godt for dette exoplanetsystem. Den vil kunne studeres i større deltalje af instrumenterne ombord på NASA/ESA/CSA James Webb Space Telescope (JWST), som nu planlægges opsendt i 2019.
Lektor Simon Albrecht fra Stellar Astrophysics Centre på Aarhus Universitet studerer også de exoplaneter, som kredser om rødfarvede stjerner. Han har ikke været direkte involveret i dette forskningsresultat, men er begejstret for den nyopdagede gasplanet. "Det er ganske usædvanligt at se denne kombination af exoplanet og M-dværgstjerne, og vi kan helt sikkert lære mere om udviklingen i planetsystemer af dette her. NGTS vil i fremtiden være et fremragende værktøj til også at kunne følge op på de opdagelser af exoplaneter omkring klare stjerner, som den kommende satellit TESS vil levere fra næste år."
Note
[1] En M-dværg er en lille, svagtlysende stjerne, som vejer et sted imellem 8 og 50% af Solen, og som har en overfladetemperatur på mindre end 3700°C. 50 ud af de 60 nærmeste stjerner omkring Solen menes at være M-dværge, men ikke en eneste af dem er klar nok eller tæt nok på os til at vi kan se den fra Jorden med det blotte øje.
Flere oplysninger
Opdagelsen bliver offentliggjort i en artikel med titlen “NGTS-1b: A hot Jupiter transiting an M-dwarf”, af D. Bayliss et al., i tidsskriftet Monthly Notices of the Royal Astronomical Society.
The team is composed of: D. Bayliss (Université de Genève, Schweiz), E. Gillen (University of Cambridge, United Kingdom), P. Eigmüller (DLR, Tyskland), J. McCormac (University of Warwick, United Kingdom), R. Alexander (University of Leicester, United Kingdom), D. Armstrong (University of Warwick, United Kingdom), R. Booth (Queen's University Belfast, United Kingdom), F. Bouchy (Université de Genève, Schweiz), M. Burleigh, J. Cabrera (DLR, Tyskland), S. Casewell, A. Chaushev (University of Leicester, United Kingdom), B. Chazelas, S. Csizmadia, A. Erikson, F. Faedi (University of Warwick, United Kingdom), E. Foxwell (University of Warwick, United Kingdom), B. Gaensicke (University of Warwick, United Kingdom), M. Goad (University of Leicester, United Kingdom), A. Grange, M. Guenther (University of Cambridge, United Kingdom), S. Hodgkin (University of Cambridge, United Kingdom), J. Jackman, J. Jenkins (Universidad de Chile, Chile), G. Lambert (University of Cambridge), T. Louden (University of Warwick, United Kingdom), L. Metrailler (Université de Genève, Schweiz), M. Moyano (Universidad Católica del Norte, Chile), D. Pollacco (University of Warwick, United Kingdom), K. Poppenhaeger, (Queen's University Belfast, United Kingdom; Harvard-Smithsonian Center for Astrophysics, USA), D. Queloz (Université de Genève, Schweiz), R. Raddi (University of Warwick, United Kingdom), H. Rauer (DLR, Tyskland), L. Raynard (University of Leicester, United Kingdom), A. Smith, M. Soto (Universidad de Chile, Chile), A. Thompson (Queen’s University Belfast, United Kingdom), R. Titz-Weider (DLR, Tyskland), S. Udry (Université de Genève, Schweiz), S. Walker (University of Warwick, United Kingdom), C. Watson (Queen's University Belfast, United Kingdom), R. West (University of Warwick, United Kingdom) and P.J. Wheatley (University of Warwick, United Kingdom).
Links
- Originalartikel 1: The Next Generation Transit Survey (NGTS)
- Originalartikel 2: NGTS-1b: A hot Jupiter transiting an M-dwarf
Kontakter
Ole J. Knudsen
ESON-Danmark
Stellar Astrophysics Centre, Aarhus Universitet
telefon 8715 5597, mobil 4059 4520
e-mail: eson-denmark@eso.org
Om meddelelsen
Id: | ann17076 |
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