V1400 Centauri, also known as 1SWASP J140747.93−394542.6 or simply J1407, is a young,

pre-main-sequence star A pre-main-sequence star (also known as a PMS star and PMS object) is a star in the stage when it has not yet reached the main sequence. Earlier in its life, the object is a protostar that grows by acquiring mass from its surrounding envelope o ...

that was

eclipse An eclipse is an astronomical event which occurs when an astronomical object or spacecraft is temporarily obscured, by passing into the shadow of another body or by having another body pass between it and the viewer. This alignment of three ...

d by the likely free-floating

substellar object A substellar object, sometimes called a substar, is an astronomical object, the mass of which is smaller than the smallest mass at which hydrogen fusion can be sustained (approximately 0.08 solar masses). This definition includes brown dwarfs and f ...

J1407b J1407b is a substellar object, either a Rogue planet, free-floating planet or brown dwarf, with a large circumplanetary disk or ring system. It was first detected by automated telescopes in 2007 when its disk eclipsed the star V1400 Cent ...

in April–June 2007. With an age around 20 million years, the star is about as massive as the Sun and is located in the constellation

Centaurus Centaurus () is a bright constellation in the southern sky. One of the 88 modern constellations by area, largest constellations, Centaurus was included among the 48 constellations listed by the 2nd-century astronomer Ptolemy, and it remains one ...

at a distance of 451

light-years A light-year, alternatively spelled light year (ly or lyr), is a unit of length used to express astronomical distances and is equal to exactly , which is approximately 9.46 trillion km or 5.88 trillion mi. As defined by the International Astro ...

away from the Sun. V1400 Centauri is a member of Upper Centaurus–Lupus subgroup of the

Scorpius–Centaurus association The Scorpius–Centaurus association (sometimes called Sco–Cen or Sco OB2) is the nearest OB association to the Sun. This stellar association is composed of three subgroups (Upper Scorpius, Upper Centaurus–Lupus, and Lower Centaurus–Crux) ...

, a group of young, comoving stars close to the Sun.

Name and catalogue history

The star has been catalogued in as early as the 1990s by the Hubble

Guide Star Catalog The Guide Star Catalog (GSC), also known as the ''Hubble Space Telescope, Guide Catalog'' (''HSTGC''), is a star catalog compiled to support the Hubble Space Telescope with targeting off-axis stars. GSC-I contained approximately 20,000,000 stars w ...

, which identified the star and measured its position in a pair of

photographic plate Photographic plates preceded film as the primary medium for capturing images in photography. These plates, made of metal or glass and coated with a light-sensitive emulsion, were integral to early photographic processes such as heliography, d ...

s taken in 1974 and 1979. The star has been catalogued by other

sky survey An astronomical survey is a general celestial cartography, map or astrophotography, image of a region of the sky (or of the whole sky) that lacks a specific observational target. Alternatively, an astronomical survey may comprise a set of image ...

s, including the

All Sky Automated Survey The All Sky Automated Survey (ASAS) is a Polish project implemented on 7 April 1997 to do photometric monitoring of approximately 20 million stars brighter than 14 magnitude all over the sky. The automatic telescopes discovered two new comets i ...

(ASAS), Two Micron All-Sky Survey (2MASS), Super Wide Angle Search for Planets (1SWASP), and the

Wide-field Infrared Survey Explorer Wide-field Infrared Survey Explorer (WISE, List of observatory codes, observatory code C51, Explorer 92 and MIDEX-6) was a NASA infrared astronomy Space observatory, space telescope in the Explorers Program launched in December 2009.. . WISE L ...

(WISE). Typically in these catalogues, the star is given designations such as 1SWASP J140747.93–394542.6, which comprises the survey name followed by the star's location in

equatorial coordinates The equatorial coordinate system is a celestial coordinate system widely used to specify the positions of celestial objects. It may be implemented in spherical or rectangular coordinates, both defined by an origin at the centre of Earth, a fun ...

. As such designations can be unwieldy, researchers simply call the star "J1407". The star was given the official

variable star designation In astronomy, a variable-star designation is a unique identifier given to variable stars. It extends the Bayer designation format, with an identifying label (as described below) preceding the Latin genitive of the name of the constellation in whic ...

V1400 Centauri in 2015, when it was added to the

International Astronomical Union 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 ...

General Catalogue of Variable Stars The General Catalogue of Variable Stars (GCVS) is a list of variable stars in the Milky Way Galaxy. Its first edition, containing 10,820 stars, was published in 1948 by the Academy of Sciences of the USSR, edited by and Pavel Parenago. Second a ...

. A 2018 research paper on stars with unusual dimming periods nicknamed V1400 Centauri "Mamajek's Object", after the astronomer Eric Mamajek who identified the star's unusual dimming in 2007.

Stellar properties

Location and age

V1400 Centauri is located in the constellation

, about 40 degrees south of the

celestial equator The celestial equator is the great circle of the imaginary celestial sphere on the same plane as the equator of Earth. By extension, it is also a plane of reference in the equatorial coordinate system. Due to Earth's axial tilt, the celestial ...

. The most recent

parallax Parallax is a displacement or difference in the apparent position of an object viewed along two different sightline, lines of sight and is measured by the angle or half-angle of inclination between those two lines. Due to perspective (graphica ...

measurements by the ''

Gaia In Greek mythology, Gaia (; , a poetic form of ('), meaning 'land' or 'earth'),, , . also spelled Gaea (), is the personification of Earth. Gaia is the ancestral mother—sometimes parthenogenic—of all life. She is the mother of Uranus (S ...

'' spacecraft indicate V1400 Centauri is located from the Sun. Observations of V1400 Centauri's position over time have shown that it has a southwestward

proper motion Proper motion is the astrometric measure of changes in the apparent places of stars or other celestial objects as they move relative to the center of mass of the Solar System. It is measured relative to the distant stars or a stable referenc ...

consistent with that of the

, an

OB association The Ob (; ) is a major river in Russia. It is in western Siberia, and with its tributary the Irtysh forms the world's seventh-longest river system, at . The Ob forms at the confluence of the Biya and Katun which have their origins in the Al ...

of young stars with ages between 11–17 million years and distances between from the Sun. The Scorpius–Centaurus association is the nearest OB association to the Sun, and is believed to have formed out of a

molecular cloud A molecular cloud—sometimes called a stellar nursery if star formation is occurring within—is a type of interstellar cloud of which the density and size permit absorption nebulae, the formation of molecules (most commonly molecular hydrogen, ...

that has since been blown away by the

stellar wind A stellar wind is a flow of gas ejected from the stellar atmosphere, upper atmosphere of a star. It is distinguished from the bipolar outflows characteristic of young stars by being less collimated, although stellar winds are not generally spheri ...

s of the association's most massive stars. V1400 Centauri is closest to the Upper Centaurus–Lupus subgroup of the Scorpius–Centaurus association, which has an age range of 14–18 million years and distance range of . Given V1400 Centauri's similar distance and proper motion, it very likely belongs to the Scorpius–Centaurus association, which would mean it must be a young star within the age range of the Upper Centaurus–Lupus subgroup. A 2012 estimate of V1400 Centauri's age assumes it is equal to 16 million years, the mean age of the Upper Centaurus–Lupus subgroup, while a 2018 estimate from ''Gaia'' measurements puts the star's age at million years.

Spectral type and physical characteristics

V1400 Centauri is a pre-main sequence star of

spectral class 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 ...

K5 IVe Li. "K" means V1400 Centauri is an orange K-type star, and the adjoining number "5" ranks V1400 Centauri's relative temperature on a scale of 9 (coolest) to 0 (hottest) for K-type stars. V1400 Centauri is given the

subgiant A subgiant is a star that is brighter than a normal main-sequence star of the same spectral class, but not as bright as giant stars. The term subgiant is applied both to a particular spectral luminosity class and to a stage in the evolution ...

luminosity class 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 gratin ...

"IV", because it has a brighter

luminosity Luminosity is an absolute measure of radiated electromagnetic radiation, electromagnetic energy per unit time, and is synonymous with the radiant power emitted by a light-emitting object. In astronomy, luminosity is the total amount of electroma ...

than

K-type main-sequence star A K-type main-sequence star, also referred to as a K-type dwarf, or orange dwarf, is a main-sequence (hydrogen-burning) star of spectral type K and luminosity class V. These stars are intermediate in size between red M-type main-sequence stars ...

s (luminosity class V). The letter "e" indicates V1400 Centauri exhibits weak

hydrogen-alpha Hydrogen-alpha, typically shortened to H-alpha or Hα, is a deep-red visible spectral line of the hydrogen atom with a wavelength of 656.28 nm in air and 656.46 nm in vacuum. It is the first spectral line in the Balmer series and is emit ...

emission line A spectral line is a weaker or stronger region in an otherwise uniform and continuous spectrum. It may result from emission or absorption of light in a narrow frequency range, compared with the nearby frequencies. Spectral lines are often used ...

s in its

visible light Light, visible light, or visible radiation is electromagnetic radiation that can be perceived by the human eye. Visible light spans the visible spectrum and is usually defined as having wavelengths in the range of 400–700 nanometres (nm ...

spectrum. Lastly, "Li" indicates V1400 Centauri is abundant in

lithium Lithium (from , , ) is a chemical element; it has chemical symbol, symbol Li and atomic number 3. It is a soft, silvery-white alkali metal. Under standard temperature and pressure, standard conditions, it is the least dense metal and the ...

. Measurements from the ''Gaia'' spacecraft's third and most recent data release (''Gaia'' DR3) indicate V1400 Centauri is about 7% larger than the Sun in radius (), but is slightly less massive than the Sun. Depending on whether magnetic effects are taken into account in V1400 Centauri's

stellar evolution Stellar evolution is the process by which a star changes over the course of time. Depending on the mass of the star, its lifetime can range from a few million years for the most massive to trillions of years for the least massive, which is consi ...

or not, the star's mass could be either or , respectively. Young stars tend to be magnetically active, and neglecting their magnetic effects results in an underestimation of their mass. An older estimate of V1400 Centauri's mass from ''Gaia''s second data release (''Gaia'' DR2) in 2018 gives , but does not take magnetic effects into account. V1400 Centauri is cooler and less luminous than the Sun, with an effective temperature of about and a luminosity about 34% that of the Sun. V1400 Centauri has an estimated

surface gravity The surface gravity, ''g'', of an astronomical object is the gravitational acceleration experienced at its surface at the equator, including the effects of rotation. The surface gravity may be thought of as the acceleration due to gravity experi ...

of about (over 20 times the

gravity of Earth The gravity of Earth, denoted by , is the net force, net acceleration that is imparted to objects due to the combined effect of gravitation (from mass distribution within Earth) and the centrifugal force (from the Earth's rotation). It is a Eucl ...

), based on ''Gaia'' measurements of the star's brightness, distance, and color. ''Gaia'' measurements also indicate V1400 Centauri has a lower

metallicity In astronomy, metallicity is the Abundance of the chemical elements, abundance of Chemical element, elements present in an object that are heavier than hydrogen and helium. Most of the normal currently detectable (i.e. non-Dark matter, dark) matt ...

than the Sun. Viewed from Earth, V1400 Centauri appears marginally redder than a typical K5-type star due to light extinction by

interstellar dust Cosmic dustalso called extraterrestrial dust, space dust, or star dustis dust that occurs in outer space or has fallen onto Earth. Most cosmic dust particles measure between a few molecules and , such as micrometeoroids (30 μm). Cosmic dust can ...

between Earth and the star. The star does not exhibit excess

thermal emission Thermal radiation is electromagnetic radiation emitted by the thermal motion of particles in matter. All matter with a temperature greater than absolute zero emits thermal radiation. The emission of energy arises from a combination of electro ...

in near- and mid-

infrared Infrared (IR; sometimes called infrared light) is electromagnetic radiation (EMR) with wavelengths longer than that of visible light but shorter than microwaves. The infrared spectral band begins with the waves that are just longer than those ...

wavelengths and lacks strong emission lines in its spectrum, which indicates it lacks a substantial

accretion disk An accretion disk is a structure (often a circumstellar disk) formed by diffuse material in orbital motion around a massive central body. The central body is most frequently a star. Friction, uneven irradiance, magnetohydrodynamic effects, and ...

protoplanetary disk A protoplanetary disk is a rotating circumstellar disc of dense gas and dust surrounding a young newly formed star, a T Tauri star, or Herbig Ae/Be star. The protoplanetary disk may not be considered an accretion disk; while the two are sim ...

Rotation and variability

Like most young stars, V1400 Centauri rotates rapidly with a rotation period of approximately 3.2 days. The rapid rotation of V1400 Centauri strengthens its magnetic field via the dynamo process, which leads to the formation of

starspot Starspots are stellar phenomena, so-named by analogy with sunspots. Spots as small as sunspots have not been detected on other stars, as they would cause undetectably small fluctuations in brightness. The commonly observed starspots are in gene ...

s on its surface. As V1400 Centauri rotates, its starspots come into and out of view, causing the star's brightness to periodically fluctuate by 5%, or about 0.1

magnitude Magnitude may refer to: Mathematics *Euclidean vector, a quantity defined by both its magnitude and its direction *Magnitude (mathematics), the relative size of an object *Norm (mathematics), a term for the size or length of a vector *Order of ...

s in

amplitude The amplitude of a periodic variable is a measure of its change in a single period (such as time or spatial period). The amplitude of a non-periodic signal is its magnitude compared with a reference value. There are various definitions of am ...

. The star's rotation period varies by 0.02 days over a 5.4-year-long magnetic activity cycle, due to the long-term movement of starspots across the star's differentially rotating surface. V1400 Centauri is known to emit

soft X-ray An X-ray (also known in many languages as Röntgen radiation) is a form of high-energy electromagnetic radiation with a wavelength shorter than those of ultraviolet rays and longer than those of gamma rays. Roughly, X-rays have a wavelength ran ...

s due to its

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 or disease responsible for the COVID-19 ...

being heated by its rotationally-strengthened magnetic field. Because of its young age, starspot variability, and lack of dust accretion, V1400 Centauri is classified as a weak-lined T Tauri variable.

Spectroscopic Spectroscopy is the field of study that measures and interprets electromagnetic spectra. In narrower contexts, spectroscopy is the precise study of color as generalized from visible light to all bands of the electromagnetic spectrum. Spectrosc ...

measurements of

Doppler broadening In atomic physics, Doppler broadening is broadening of spectral lines due to the Doppler effect caused by a distribution of velocities of atoms or molecules. Different velocities of the emitting (or absorbing) particles result in different Doppl ...

in V1400 Centauri's spectral absorption lines indicate the star has a projected rotational velocity of . Given V1400 Centauri's rotation period, radius, and temperature, the star's true equatorial rotation velocity is , which indicates that the star's rotation axis is inclined with respect to Earth's line of sight.

2007 eclipse by J1407b

During 7 April to 4 June 2007, telescopes of the Super

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 ...

(SuperWASP) and

(ASAS) projects recorded V1400 Centauri undergoing a series of significant dimming events for 56 days. The pattern of these dimming events was complex yet nearly symmetrical, indicating they were caused by an opaque, disk-like structure eclipsing the star. The object that eclipsed V1400 Centauri is now known as

, a

surrounded by a dusty

circumplanetary disk A circumplanetary disk (or circumplanetary disc, short CPD) is a torus, pancake or ring-shaped accumulation of matter composed of gas, dust, planetesimals, asteroids or collision fragments in orbit around a planet. They are reservoirs of materi ...

about in radius. V1400 Centauri's eclipse by J1407b was discovered on 3 December 2010 by Mark Pecaut, who was a

graduate student Postgraduate education, graduate education, or graduate school consists of Academic degree, academic or professional degrees, certificates, diplomas, or other qualifications usually pursued by higher education, post-secondary students who have ...

of Eric E. Mamajek at the

University of Rochester The University of Rochester is a private university, private research university in Rochester, New York, United States. It was founded in 1850 and moved into its current campus, next to the Genesee River in 1930. With approximately 30,000 full ...

. Mamajek, Pecaut, and collaborators announced the discovery in 2012. Mamajek's team initially hypothesized that J1407b is a

ringed Bird ringing (UK) or bird banding (US) is the attachment of a small, individually numbered metal or plastic tag to the leg or wing of a wild bird to enable individual identification. This helps in keeping track of the movements of the bird an ...

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 ...

brown dwarf Brown dwarfs are substellar objects that have more mass than the biggest gas giant planets, but less than the least massive main sequence, main-sequence stars. Their mass is approximately 13 to 80 Jupiter mass, times that of Jupiter ()not big en ...

orbiting the star, but that has since been disfavored by later studies. V1400 Centauri does not show repeating eclipses, telescope observations showed no orbiting companions, and the disk of J1407b would be unstable if it orbited the star, which suggests that J1407b likely does not orbit V1400 Centauri and is instead a free-floating object that coincidentally passed in front of the star. In this case, J1407b's coincidental eclipse of V1400 Centauri would be considered an extremely rare event that will never happen again. High-resolution imaging by the

Atacama Large Millimeter Array The Atacama Large Millimeter/submillimeter Array (ALMA) is an astronomical interferometer of 66 radio telescopes in the Atacama Desert of northern Chile, which observe electromagnetic radiation at millimeter and submillimeter wavelengths. The ar ...

(ALMA) in 2017 revealed a single object near V1400 Centauri, which might be J1407b. The object's distance from V1400 Centauri appears to match the expected distance travelled by J1407b if it was a free-floating object. The object's brightness is suggestive of a dusty circumplanetary disk surrounding a

planetary-mass object A planetary-mass object (PMO), planemo, or planetary body (sometimes referred to as a world) is, by geophysical definition of celestial objects, any celestial object massive enough to achieve hydrostatic equilibrium, but not enough to sustain c ...

below 6

Jupiter mass The Jupiter mass, also called Jovian mass, is the unit of mass equal to the total mass of the planet Jupiter. This value may refer to the mass of the planet alone, or the mass of the entire Jovian system to include the moons of Jupiter. Jupiter ...

es. However, the object has only been observed by ALMA once, so it is not yet known whether it is a moving foreground object or a stationary background

galaxy A galaxy is a Physical system, system of stars, stellar remnants, interstellar medium, interstellar gas, cosmic dust, dust, and dark matter bound together by gravity. The word is derived from the Ancient Greek, Greek ' (), literally 'milky', ...

. Recent observations by ALMA in June and July 2024 will confirm whether this object is J1407b or not.

Notes

References

External links

Eric Mamajek's webpage at University of Rochester

Matthew Kenworthy's webpage on J1407b

Rings around another world may have been sculpted by exomoons
Ruth Angus, ''Astrobites'', 5 February 2015. {{DEFAULTSORT:V1400 Centauri Centaurus Hypothetical planetary systems Variable stars Pre-main-sequence stars Upper Centaurus Lupus J14074792-3945427 Centauri, V1400 K-type stars