'Lost' world's rediscovery is step towards finding habitable planets


Date:
July 21, 2020
Source:
University of Warwick
Summary:
The rediscovery of a lost planet could pave the way for the
detection of a world within the habitable 'Goldilocks zone' in a
distant solar system.



FULL STORY ==========================================================================
The rediscovery of a lost planet could pave the way for the detection of
a world within the habitable 'Goldilocks zone' in a distant solar system.


==========================================================================
The planet, the size and mass of Saturn with an orbit of thirty-five
days, is among hundreds of 'lost' worlds that University of Warwick
astronomers are pioneering a new method to track down and characterise
in the hope of finding cooler planets like those in our solar system,
and even potentially habitable planets.

Reported in Astrophysical Journal Letters, the planet named NGTS-11b
orbits a star 620 light years away and is located five times closer to
its sun than Earth is to our own.

The planet was originally found in a search for planets in 2018 by the
Warwick- led team using data from NASA's TESS telescope. This uses the
transit method to spot planets, scanning for the telltale dip in light
from the star that indicates that an object has passed between the
telescope and the star.

However, TESS only scans most sections of the sky for 27 days. This
means many of the longer period planets only transit once in the TESS
data. And without a second observation the planet is effectively lost. The University of Warwick led team followed up one of these 'lost' planets
using the telescopes at the Next-Generation Transit Survey (NGTS) in
Chile and observed the star for seventy-nine nights, eventually catching
the planet transiting for a second time nearly a year after the first
detected transit.

Dr Samuel Gill from the Department of Physics at the University of
Warwick said: "By chasing that second transit down we've found a longer
period planet.

It's the first of hopefully many such finds pushing to longer periods.

"These discoveries are rare but important, since they allow us to find
longer period planets than other astronomers are finding. Longer period
planets are cooler, more like the planets in our own Solar System.

"NGTS-11b has a temperature of only 160DEGC -- cooler than Mercury
and Venus.

Although this is still too hot to support life as we know it, it is
closer to the Goldilocks zone than many previously discovered planets
which typically have temperatures above 1000DEGC." The Goldilocks zone
refers to a range of orbits that would allow a planet or moon to support
liquid water: too close to its star and it will be too hot, but too far
away and it will be too cold.

Co-author Dr Daniel Bayliss from the University of Warwick said:
"This planet is out at a thirty-five days orbit, which is a much longer
period than we usually find them. It is exciting to see the Goldilocks
zone within our sights." Co-author Professor Pete Wheatley from the
University of Warwick said: "The original transit appeared just once
in the TESS data, and it was our team's painstaking detective work that
allowed us to find it again a year later with NGTS.

"NGTS has twelve state-of-the-art telescopes, which means that we can
monitor multiple stars for months on end, searching for lost planets. The
dip in light from the transit is only 1% deep and occurs only once every
35 days, putting it out of reach of other telescopes. " Dr Gill adds:
"There are hundreds of single transits detected by TESS that we will
be monitoring using this method. This will allow us to discover cooler exoplanets of all sizes, including planets more like those in our own
Solar System. Some of these will be small rocky planets in the Goldilocks
zone that are cool enough to host liquid water oceans and potentially extraterrestrial life."

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


========================================================================== Journal Reference:
1. Samuel Gill, Peter J. Wheatley, Benjamin F. Cooke, Andre's Jorda'n,
Louise D. Nielsen, Daniel Bayliss, David R. Anderson, Jose I. Vines,
Monika Lendl, Jack S. Acton, David J. Armstrong, Franc,ois
Bouchy, Rafael Brahm, Edward M. Bryant, Matthew R. Burleigh,
Sarah L. Casewell, Philipp Eigmu"ller, Ne'stor Espinoza, Edward
Gillen, Michael R. Goad, Nolan Grieves, Maximilian N. Gu"nther,
Thomas Henning, Melissa J. Hobson, Aleisha Hogan, James S. Jenkins,
James McCormac, Maximiliano Moyano, Hugh P. Osborn, Don Pollacco,
Didier Queloz, Heike Rauer, Liam Raynard, Felipe Rojas, Paula
Sarkis, Alexis M. S. Smith, Marcelo Tala Pinto, Rosanna H.

Tilbrook, Ste'phane Udry, Christopher A. Watson, Richard
G. West. NGTS-11 b (TOI-1847 b): A Transiting Warm Saturn Recovered
from a TESS Single- transit Event. The Astrophysical Journal,
2020; 898 (1): L11 DOI: 10.3847/2041-8213/ab9eb9 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2020/07/200721114732.htm

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