`Planet confusion' could slow Earth-like exoplanet exploration

Date:
September 30, 2021
Source:
Cornell University
Summary:
A new study finds that next-generation telescopes used to see
exoplanets could confuse Earth-like planets with other types of
planets in the same solar system.



FULL STORY ==========================================================================
When it comes to directly imaging Earth-like exoplanets orbiting faraway
stars, seeing isn't always believing. A new Cornell University study finds
that next- generation telescopes used to see exoplanets could confuse Earth-like planets with other types of planets in the same solar system.


==========================================================================
With today's telescopes, dim distant planets are hard to see against
the glare of their host stars, but next-generation tools such as the
Nancy Grace Roman Space Telescope, currently under development by NASA,
will be better at imaging Earth-like planets, which orbit stars at just
the right distance to offer prime conditions for life.

"Once we have the capability of imaging Earth-like planets, we're
actually going to have to worry about confusing them with completely
different types of planets," said Dmitry Savransky, associate professor
of mechanical and aerospace engineering and of astronomy.

"The future telescopes that will enable these observations will be so
huge, expensive, and difficult to build and launch that we can't afford
to waste a single second of time on them," Savransky said, "which is
why it is so important to think through all of these potential issues
ahead of time." By using Earth's own solar system as a model of an
unexplored star system, Savransky and doctoral student Dean Keithly,
calculated that even with direct- imaging techniques and the increased capabilities of future, high-powered telescopes, exoplanets as different
as Uranus and Earth could be mistaken for one another.

The research details how measurements estimating planet-star separation
and brightness can cause "planet confusion." The modeling finds that when
two planets share the same separation and magnitude along their orbits,
one planet can be confused for the other.

Keithly and Savransky identified 21 cases within their solar system model
in which an individual planet had the same apparent planet-star separation
and brightness as another planet. Using this data, it was calculated that
an Earth- like planet could be misidentified with a Mercury-like planet
in 36% of randomly generated solar systems; with a Mars-like planet in
about 43% of randomly generated solar systems; and with a Venus-like
planet in more than 72% of randomly generated solar systems.

In contrast, confusion between Earth-like planets and larger gas-giant
planets similar to Neptune, Saturn and Uranus was less likely, and could
occur in 1-4% of randomly generated solar systems.

Confusing planets for one another can be an expensive and time-consuming problem for scientists. Extensive planning and funds go into each use
of a high-powered telescope, so the false identification of a habitable exoplanet wastes valuable telescope time. With this problem identified, researchers can design more efficient exoplanet direct-imaging mission
surveys.

The researchers warn that further improvements to instrument contrast
and inner-working angles could exacerbate the problem and advise that
future exoplanet direct-imaging missions make multiple observations to
more accurately differentiate between planets.

========================================================================== Story Source: Materials provided by Cornell_University. Original written
by Erin Philipson.

Note: Content may be edited for style and length.


========================================================================== Journal Reference:
1. Dean Robert Keithly, Dmitry Savransky. The Solar System as an
Exosystem:
Planet Confusion. The Astrophysical Journal Letters, 2021; 919
(1): L11 DOI: 10.3847/2041-8213/ac20cf ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2021/09/210930134800.htm

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