Artists performance of the Kepler-47 circumbinary planet system with its three planets. Kepler and TESS spot worlds through the transit technique, where astronomers determine the small dimming of a star as a planet passes in front of its host star, obstructing some of the starlight.” Detecting circumbinary planets is much more complex than discovering planets orbiting single stars. While that was not an issue with the Kepler space telescope (this telescope observed just one region of the sky for 3.5 years), it makes it challenging to use the TESS telescope to identify circumbinary worlds, since TESS observes one portion (or sector) of the sky for only 27 days prior to pointing someplace else, making it impossible to observe three transits of a planet with TESS.
The brand-new planet is the evidence of the validity, applicability and success of our created method,” stated Haghighipour, creator of the TESS Circumbinary Planet Working Group.
Artists rendition of the Kepler-47 circumbinary planet system with its 3 worlds. Credit: NASA/JPL-Caltech/T. Pyle
A brand-new method developed in part by University of Hawaiʻi astronomer Nader Haghighipour has permitted scientists to quickly identify a transiting planet with two suns.
Described circumbinary planets, these objects orbit around a set of stars. For years, these worlds were simply the topic of sci-fi, like Tatooine in Star Wars. Thanks to NASAs effective planet-hunting Kepler and Transiting Exoplanet Survey Satellite (TESS) missions, a group of astronomers, including Haghighipour, have found 14 such bodies so far.
Kepler and TESS detect planets by means of the transit method, where astronomers measure the tiny dimming of a star as a planet passes in front of its host star, obstructing some of the starlight. Typically, astronomers need to see a minimum of three of these transits to select the planets orbit. This becomes challenging when there are 2 host stars..
Artists rendering of the TIC 172900988 circumbinary planetary system shows the two suns orbited by the spotted planet. The size of the Earths orbit is revealed for comparison. Credit: UH IfA/Brooks Bays.
” Detecting circumbinary worlds is a lot more complicated than finding planets orbiting single stars. When a world orbits a double-star system, transits of the exact same star dont happen at consistent intervals,” discussed Haghighipour. “The planet might transit one star, and after that transit the other, before transiting the first star once again, and so on.”.
Contributing to the difficulty, the orbital periods of circumbinary planets are always a lot longer than the orbital duration of the binary star. That implies, in order to observe three transits, scientists require to observe the binary for a long period of time. While that was not a problem with the Kepler area telescope (this telescope observed just one region of the sky for 3.5 years), it makes it challenging to use the TESS telescope to spot circumbinary worlds, since TESS observes one portion (or sector) of the sky for just 27 days prior to pointing someplace else, making it impossible to observe 3 transits of a planet with TESS.
Artists impression of the simultaneous stellar eclipse and planetary transit events on Kepler-1647. Such a double eclipse event is referred to as a syzygy. Credit: Lynette Cook.
In 2020, Haghighipour and his group found a way around this constraint. In a post released in The Astronomical Journal, they described a novel technique that would allow them to identify circumbinary worlds using TESS, as long as the planet transited both of its host stars within the 27-day observing window.
Now, that same team of astronomers has actually found the very first such circumbinary planet in TESS information, showing that their technique works. The target binary is known by its catalog classification, TIC 172900988, and was observed in a single sector by TESS, where its lightcurve showed signs of two transits, one across each star, separated by simply 5 days– during the same combination..
” This planets orbit takes almost 200 days– with the conventional transit approach, we would have required to wait over a year to detect two extra transits. Our new method reduced that time to simply 5 days, revealing that in spite of its brief window of observation, TESS can be used to detect circumbinary planets. The new planet is the evidence of the validity, applicability and success of our developed strategy,” stated Haghighipour, founder of the TESS Circumbinary Planet Working Group. “This discovery shows that our brand-new method works and will have the ability to find a lot more worlds.”.
The discovery of the very first TESS circumbinary world using this brand-new strategy appears in The Astronomical Journal. Haghighipour is a co-author with lead authors Veselin B. Kostov (NASA Goddard Space Flight Center), SETI Institute, and GSFC Sellers Exoplanet Environments Collaboration..
Referral: “TIC 172900988: A Transiting Circumbinary Planet Detected in One Sector of TESS Data” by Veselin B. Kostov, Brian P. Powell, Jerome A. Orosz, William F. Welsh, William Cochran, Karen A. Collins, Michael Endl, Coel Hellier, David W. Latham, Phillip MacQueen, Joshua Pepper, Billy Quarles, Lalitha Sairam, Guillermo Torres, Robert F. Wilson, Serge Bergeron, Pat Boyce, Allyson Bieryla, Robert Buchheim, Caleb Ben Christiansen, David R. Ciardi, Kevin I. Collins, Dennis M. Conti, Scott Dixon, Pere Guerra, Nader Haghighipour, Jeffrey Herman, Eric G. Hintz, Ward S. Howard, Eric L. N. Jensen, John F. Kielkopf, Ethan Kruse, Nicholas M. Law, David Martin, Pierre F. L. Maxted, Benjamin T. Montet, Felipe Murgas, Matt Nelson, Greg Olmschenk, Sebastian Otero, Robert Quimby, Michael Richmond, Richard P. Schwarz, Avi Shporer, Keivan G. Stassun, Denise C. Stephens, Amaury H. M. J. Triaud, Joe Ulowetz, Bradley S. Walter, Edward Wiley, David Wood, Mitchell Yenawine, Eric Agol, Thomas Barclay, Thomas G. Beatty, Isabelle Boisse, Douglas A. Caldwell, Jessie Christiansen, Knicole D. Colón, Magali Deleuil, Laurance Doyle, Michael Fausnaugh, Gábor Furész, Emily A. Gilbert, Guillaume Hébrard, David J. James, Jon Jenkins, Stephen R. Kane, Richard C. Kidwell Jr., Ravi Kopparapu, Gongjie Li, Jack J. Lissauer, Michael B. Lund, Steve R. Majewski, Tsevi Mazeh, Samuel N. Quinn, Elisa Quintana, George Ricker, Joseph E. Rodriguez, Jason Rowe, Alexander Santerne, Joshua Schlieder, Sara Seager, Matthew R. Standing, Daniel J. Stevens, Eric B. Ting, Roland Vanderspek and Joshua N. Winn, 10 November 2021, The Astronomical Journal.DOI: 10.3847/ 1538-3881/ ac223a.
Funding for this work was provided in part by NASA.