WASP-161, also named Tislit, is an

F-type main-sequence star An F-type main-sequence star (F V) is a main-sequence, hydrogen-fusing star of spectral type F and luminosity class V. These stars have from 1.0 to 1.4 times the mass of the Sun and surface temperatures between 6,000 and 7,600 K.Tables ...

about away in the constellation

Puppis Puppis ("poop deck, stern") is a constellation in the southern sky. It was originally part of the Former constellations, traditional constellation of Argo Navis (the ship of Jason and the Argonauts), which was divided into three parts, the other ...

. With an

apparent magnitude Apparent magnitude () is a measure of the Irradiance, brightness of a star, astronomical object or other celestial objects like artificial satellites. Its value depends on its intrinsic luminosity, its distance, and any extinction (astronomy), ...

of 11.1, it is much too faint to be visible to the

naked eye Naked eye, also called bare eye or unaided eye, is the practice of engaging in visual perception unaided by a magnification, magnifying, Optical telescope#Light-gathering power, light-collecting optical instrument, such as a telescope or microsc ...

. It hosts one known

exoplanet An exoplanet or extrasolar planet is a planet outside the Solar System. The first confirmed detection of an exoplanet was in 1992 around a pulsar, and the first detection around a main-sequence star was in 1995. A different planet, first det ...

Nomenclature

The designation ''WASP-161'' comes from the

Wide Angle Search for Planets WASP or Wide Angle Search for Planets is an international consortium of several academic organisations performing an ultra-wide angle search for exoplanets using transit photometry. The array of robotic telescopes aims to Astronomical survey, s ...

. This was one of the systems selected to be named in the 2019

NameExoWorlds NameExoWorlds (also known as IAU NameExoWorlds) were various projects managed by the International Astronomical Union (I.A.U.) to encourage names to be submitted for astronomical objects, notably exoplanets. The accepted names would later be cons ...

campaign during the 100th anniversary of the

IAU The International Astronomical Union (IAU; , UAI) is an international non-governmental organization (INGO) with the objective of advancing astronomy in all aspects, including promoting astronomical research, outreach, education, and developmen ...

, which assigned each country a star and planet to be named. This system was assigned to

Morocco Morocco, officially the Kingdom of Morocco, is a country in the Maghreb region of North Africa. It has coastlines on the Mediterranean Sea to the north and the Atlantic Ocean to the west, and has land borders with Algeria to Algeria–Morocc ...

; it was chosen because it hosts the first exoplanet with a discovery team led by a Moroccan astronomer. The approved names were Tislit for the star and Isli for the planet; they are named after the Tislit and Isli lakes in the

Atlas Mountains The Atlas Mountains are a mountain range in the Maghreb in North Africa. They separate the Sahara Desert from the Mediterranean Sea and the Atlantic Ocean; the name "Atlantic" is derived from the mountain range, which stretches around through M ...

of Morocco, near

Imilchil Imilchil or Imilshil ( , ) is a small town in Midelt Province of central Morocco, in the Atlas Mountains with a population of about 1,858. It is located at an elevation of 2119 m in the valley of Asif Mellulen ("white river"). The area of Imilch ...

. The names mean ''bride'' and ''groom'' in the

Amazigh language The Berber languages, also known as the Amazigh languages or Tamazight, are a branch of the Afroasiatic language family. They comprise a group of closely related but mostly mutually unintelligible languages spoken by Berber communities, who ar ...

, in reference to a heartbroken couple of local legend.

Planetary system

The planet WASP-161b, later named Isli, is a massive

hot Jupiter Hot Jupiters (sometimes called hot Saturns) are a class of gas giant exoplanets that are inferred to be physically similar to Jupiter (i.e. Jupiter analogue, Jupiter analogues) but that have very short orbital periods (). The close proximity to t ...

, discovered using the

transit method Methods of detecting exoplanets usually rely on indirect strategies – that is, they do not directly image the planet but deduce its existence from another signal. Any planet is an extremely faint light source compared to its parent star. For e ...

as part of the

(WASP). The discovery team, led by Khalid Barkaoui of

Cadi Ayyad University Cadi Ayyad University (, ), also known as the University of Marrakesh, is one of the largest universities in Morocco. One of its associated colleges, the École nationale des sciences appliquées de Marrakech (ENSA Marrakech), was created in 200 ...

, used other telescopes, including TRAPPIST-North at the Oukaïmeden Observatory, TRAPPIST-South, and SPECULOOS-South, to confirm the planet initially detected by WASP. The discovery was announced in 2018 along with two other planets, around the stars WASP-163 and WASP-170. A 2022 study reported evidence for

transit-timing variation Transit-timing variation is a method for detecting exoplanets by observing variations in the timing of a transit. This provides an extremely sensitive method capable of detecting additional planets in the system with masses potentially as small a ...

s of WASP-161b, possibly due to

orbital decay Orbital decay is a gradual decrease of the distance between two orbiting bodies at their closest approach (the periapsis) over many orbital periods. These orbiting bodies can be a planet and its satellite, a star and any object orbiting it, or ...

precession Precession is a change in the orientation of the rotational axis of a rotating body. In an appropriate reference frame it can be defined as a change in the first Euler angle, whereas the third Euler angle defines the rotation itself. In o ...

, but this was not confirmed by a subsequent study in 2023.

References

{{Puppis Puppis F-type main-sequence stars Planetary systems with one confirmed planet Tislit BD-11 2350 50712784

1912 This year is notable for Sinking of the Titanic, the sinking of the ''Titanic'', which occurred on April 15. In Albania, this leap year runs with only 353 days as the country achieved switching from the Julian to Gregorian Calendar by skippin ...

161 Year 161 ( CLXI) was a common year starting on Wednesday of the Julian calendar. At the time, it was known as the Year of the Consulship of Caesar and Aurelius (or, less frequently, year 914 ''Ab urbe condita''). The denomination 161 for this ye ...