AD Leonis (Gliese 388) is a

red dwarf ''Red Dwarf'' is a British science fiction comedy franchise created by Rob Grant and Doug Naylor, which primarily consists of a television sitcom that aired on BBC Two between 1988 and 1999, and on Dave since 2009, gaining a cult following. T ...

star. It is located relatively near the

Sun The Sun is the star at the center of the Solar System. It is a nearly perfect ball of hot plasma, heated to incandescence by nuclear fusion reactions in its core. The Sun radiates this energy mainly as light, ultraviolet, and infrared radi ...

, at a distance of about 16

light year A light-year, alternatively spelled light year, is a large unit of length used to express astronomical distances and is equivalent to about 9.46 trillion kilometers (), or 5.88 trillion miles ().One trillion here is taken to be 1012 ...

s, in the constellation Leo. AD Leonis is a

main sequence In astronomy, the main sequence is a continuous and distinctive band of stars that appears on plots of stellar color versus brightness. These color-magnitude plots are known as Hertzsprung–Russell diagrams after their co-developers, Ejnar Her ...

star with a

spectral classification In astronomy, stellar classification is the classification of stars based on their spectral characteristics. Electromagnetic radiation from the star is analyzed by splitting it with a prism or diffraction grating into a spectrum exhibiting the ...

of M3.5V. It is a

flare star A flare star is a variable star that can undergo unpredictable dramatic increases in brightness for a few minutes. It is believed that the flares on flare stars are analogous to solar flares in that they are due to the magnetic energy stored in th ...

that undergoes random increases in luminosity.

Properties

AD Leonis is an

M-type star In astronomy, stellar classification is the classification of stars based on their spectral characteristics. Electromagnetic radiation from the star is analyzed by splitting it with a prism or diffraction grating into a spectrum exhibiting the ...

with a

spectral type In astronomy, stellar classification is the classification of stars based on their stellar spectrum, spectral characteristics. Electromagnetic radiation from the star is analyzed by splitting it with a Prism (optics), prism or diffraction grati ...

M3.5eV, indicating it is a

main sequence star Main may refer to: Geography * Main River (disambiguation) **Most commonly the Main (river) in Germany *Main, Iran, a village in Fars Province *"Spanish Main", the Caribbean coasts of mainland Spanish territories in the 16th and 17th centuries * ...

that displays emission lines in its spectrum. At a trigonometric distance of , it has an apparent visual magnitude of 9.43. It has about 39–42% of the

Sun's mass The solar mass () is a standard unit of mass in astronomy, equal to approximately . It is often used to indicate the masses of other stars, as well as stellar clusters, nebulae, galaxies and black holes. It is approximately equal to the mass of ...

— above the mass at which a star is fully convective — and 39% of the Sun's radius. The projected rotation of this star is only 3 km/s, but it completes a rotation once every 2.24 days. It is a relatively young star with an estimated age of 25–300 million years, and is considered a member of the young disk population. The variable nature of this star was first observed in 1949 by Katherine C. Gordon and Gerald E. Kron at

Lick Observatory The Lick Observatory is an astronomical observatory owned and operated by the University of California. It is on the summit of Mount Hamilton, in the Diablo Range just east of San Jose, California, United States. The observatory is managed by th ...

. AD Leonis is one of the most active

s known, and the emissions from the flares have been detected across the

electromagnetic spectrum The electromagnetic spectrum is the range of frequencies (the spectrum) of electromagnetic radiation and their respective wavelengths and photon energies. The electromagnetic spectrum covers electromagnetic waves with frequencies ranging from ...

as high as the

X-ray An X-ray, or, much less commonly, X-radiation, is a penetrating form of high-energy electromagnetic radiation. Most X-rays have a wavelength ranging from 10 picometers to 10 nanometers, corresponding to frequencies in the range 30&nb ...

band. The net magnetic flux at the surface is about 3 kG. Besides star spots, about 73% of the surface is covered by magnetically active regions. Examination of the

corona Corona (from the Latin for 'crown') most commonly refers to: * Stellar corona, the outer atmosphere of the Sun or another star * Corona (beer), a Mexican beer * Corona, informal term for the coronavirus SARS-CoV-2, which causes the COVID-19 di ...

in X-ray shows compact loop structures that span up to 30% of the size of the star. The average temperature of the corona is around 6.39 MK. During a 1943

proper motion Proper motion is the astrometric measure of the observed changes in the apparent places of stars or other celestial objects in the sky, as seen from the center of mass of the Solar System, compared to the abstract background of the more dista ...

study by

Dirk Reuyl Dirk Reuyl (1906 – 1972) was a Dutch American physicist and astronomer. He was the cousin of astronomer Peter van de Kamp. Life Like his cousin, Reuijl (later "Reuyl") was born in Kampen, Overijssel. He studied physics and mathematics at Utr ...

McCormick Observatory The Leander McCormick Observatory is one of the astronomical observatories operated by the Department of Astronomy of the University of Virginia, and is situated just outside Charlottesville, Virginia (US) in Albemarle County on the summit of Mo ...

, it was suspected of having a companion. However, a 1968 study by

Sarah L. Lippincott Sarah Lee Lippincott (October 26, 1920 – February 28, 2019), also known as Sarah Lee Lippincott Zimmerman, was an American astronomer. She was professor emerita of astronomy at Swarthmore College and director emerita of the college's Sproul Obs ...

Sproul Observatory Sproul Observatory was an astronomical observatory owned and operated by Swarthmore College. It was located in Swarthmore, Pennsylvania, United States, and named after William Cameron Sproul, the 27th Governor of Pennsylvania, who graduated ...

was unable to confirm this result. A 1997 search with a near-infrared speckle interferometer failed to detect a companion orbiting 1–10 AU from the star. In 2001, an optical

coronagraph A coronagraph is a telescopic attachment designed to block out the direct light from a star so that nearby objects – which otherwise would be hidden in the star's bright glare – can be resolved. Most coronagraphs are intended to view ...

was used to example the star, but no companion was found. There is no sign of variability in its radial velocity, which would otherwise indicate the presence of an unseen companion. This star is orbiting through the

Milky Way The Milky Way is the galaxy that includes our Solar System, with the name describing the galaxy's appearance from Earth: a hazy band of light seen in the night sky formed from stars that cannot be individually distinguished by the naked eye ...

galaxy with an

eccentricity Eccentricity or eccentric may refer to: * Eccentricity (behavior), odd behavior on the part of a person, as opposed to being "normal" Mathematics, science and technology Mathematics * Off-center, in geometry * Eccentricity (graph theory) of a v ...

of 0.028 . This carries the star as close as 8.442 kpc from the galactic core, and as far as 8.926 kpc. The orbital

inclination Orbital inclination measures the tilt of an object's orbit around a celestial body. It is expressed as the angle between a Plane of reference, reference plane and the orbital plane or Axis of rotation, axis of direction of the orbiting object ...

carries it as far as 0.121 kpc from the plane of the galaxy. In 2021, a

superflare Superflares are very strong explosions observed on stars with energies up to ten thousand times that of typical solar flares. The stars in this class satisfy conditions which should make them solar analogues, and would be expected to be stable ove ...

on AD Leo was observed simultaneously in X-ray by

XMM-Newton ''XMM-Newton'', also known as the High Throughput X-ray Spectroscopy Mission and the X-ray Multi-Mirror Mission, is an X-ray space observatory launched by the European Space Agency in December 1999 on an Ariane 5 rocket. It is the second cornerst ...

and in optical by

TESS Tess or TESS may refer to: Music * Tess (band), a Spanish pop band active from 2000 to 2005 * TESS (musician), a UK musician Film and theatre * ''Tess'' (1979 film), a 1979 film adaptation of '' Tess of the d'Urbervilles'' * ''Tess'' (2016 film) ...

Search for planets

In 2019, one candidate planet signal was detected by the

radial velocity method Doppler spectroscopy (also known as the radial-velocity method, or colloquially, the wobble method) is an indirect method for finding extrasolar planets and brown dwarfs from radial-velocity measurements via observation of Doppler shifts in t ...

but was refuted in 2020.

References

External links

* {{DEFAULTSORT:AD Leonis Leo (constellation) Local Bubble M-type main-sequence stars 0388 Leonis, AD BD+20 2465

Properties

Search for planets

See also

References

External links