New method to detect Tatooine-like planets validated

Date:
November 10, 2021
Source:
University of Hawaii at Manoa
Summary:
A new method has allowed scientists to quickly detect a transiting
planet with two suns.



FULL STORY ==========================================================================
A new technique developed in part by University of Hawaii astronomer
Nader Haghighipour has allowed scientists to quickly detect a transiting
planet with two suns.


========================================================================== Termed circumbinary planets, these objects orbit around a pair of
stars. For years, these planets were merely the subject of science
fiction, like Tatooine in Star Wars. However, thanks to NASA's successful planet-hunting Kepler and Transiting Exoplanet Survey Satellite (TESS) missions, a team of astronomers, including Haghighipour, have found 14
such bodies so far.

Kepler and TESS detect planets via the transit method, where astronomers measure the tiny dimming of a star as a planet passes in front of its
host star, blocking some of the starlight. Usually, astronomers need to
see at least three of these transits to pin down the planet's orbit. This becomes challenging when there are two host stars.

"Detecting circumbinary planets is much more complicated than finding
planets orbiting single stars. When a planet orbits a double-star system, transits of the same star don't occur at consistent intervals," explained Haghighipour.

"The planet might transit one star, and then transit the other, before transiting the first star again, and so on." Adding to the challenge,
the orbital periods of circumbinary planets are always much longer than
the orbital period of the binary star. That means, in order to observe
three transits, scientists need to observe the binary for a long time.

While that was not a problem with the Kepler space telescope (this
telescope observed only one region of the sky for 3.5 years), it makes
it challenging to use the TESS telescope to detect circumbinary planets, because TESS observes one portion (or sector) of the sky for only 27
days before pointing someplace else, making it impossible to observe
three transits of a planet with TESS.

In 2020, Haghighipour and his team found a way around this limitation. In
an article published in The Astronomical Journal, they described a novel technique that would enable them to detect circumbinary planets 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 first such circumbinary planet in TESS data, demonstrating that their technique
works. The target binary is known by its catalog designation, 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 just five days - during the same conjunction.

"This planet's orbit takes almost 200 days - with the traditional
transit method, we would have needed to wait over a year to detect two additional transits. Our new technique reduced that time to just five
days, showing that despite its short window of observation, TESS can
be used to detect circumbinary planets. The new planet is the proof of
the validity, applicability and success of our invented technique,"
said Haghighipour, founder of the TESS Circumbinary Planet Working
Group. "This discovery demonstrates that our new technique works and
will be able to find many more planets." The discovery of the first
TESS circumbinary planet using this new technique appears in the 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.

Funding for this work was provided in part by NASA.

========================================================================== Story Source: Materials provided by University_of_Hawaii_at_Manoa. Note: Content may be edited for style and length.


========================================================================== Journal Reference:
1. 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. Colon, Magali Deleuil, Laurance Doyle, Daniel Fabrycky, Michael
Fausnaugh, Gabor Furesz, Emily A. Gilbert, Guillaume Hebrard, David
J. James, Jon Jenkins, Stephen R. Kane, Richard C. Kidwell Jr.,
Ravi Kopparapu, Gongjie Li, Jack J. Lissauer, Michael B. Lund,
Steve 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,
Joshua N. Winn. TIC 172900988: A Transiting Circumbinary Planet
Detected in One Sector of TESS Data. The Astronomical Journal,
2021 [abstract] ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2021/11/211110131529.htm

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