R Sculptoris is a

variable star A variable star is a star whose brightness as seen from Earth (its apparent magnitude) changes systematically with time. This variation may be caused by a change in emitted light or by something partly blocking the light, so variable stars are ...

system in the southern

constellation A constellation is an area on the celestial sphere in which a group of visible stars forms Asterism (astronomy), a perceived pattern or outline, typically representing an animal, mythological subject, or inanimate object. The first constellati ...

Sculptor Sculpture is the branch of the visual arts that operates in three dimensions. Sculpture is the three-dimensional art work which is physically presented in the dimensions of height, width and depth. It is one of the plastic arts. Durable sc ...

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 provide a distance estimate of approximately from the

Sun The Sun is the star at the centre of the Solar System. It is a massive, nearly perfect sphere of hot plasma, heated to incandescence by nuclear fusion reactions in its core, radiating the energy from its surface mainly as visible light a ...

. An independent estimate based on measurements of an ejected shell surrounding the star yield a distance of . The star is drifting closer with a

radial velocity The radial velocity or line-of-sight velocity of a target with respect to an observer is the rate of change of the vector displacement between the two points. It is formulated as the vector projection of the target-observer relative velocity ...

of −5.4 km/s.

Benjamin Apthorp Gould Benjamin Apthorp Gould (September 27, 1824 – November 26, 1896) was a pioneering American astronomer. He is noted for creating the ''Astronomical Journal'', discovering the Gould Belt, and for founding of the Argentine National Observatory and ...

discovered that the star's brightness varies, in 1872. It was listed with its

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 ...

, R Sculptoris, in Annie Jump Cannon's 1907 work ''Second Catalog of Variable Stars''. Although the

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 ...

lists its maximum brightness as

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 ...

9.1, far too faint to be seen with 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 ...

, both

AAVSO The American Association of Variable Star Observers (AAVSO) is an international nonprofit organization. Founded in 1911, the organization focuses on coordinating, analyzing, publishing, and archiving variable star observations made largely by amat ...

and ASAS data shows that R Sculptoris is occasionally brighter than 6th magnitude, and faintly visible to the naked eye under excellent observing conditions. RSclLightCurve

This is an aging

giant star A giant star has a substantially larger radius and luminosity than a main-sequence (or ''dwarf'') star of the same surface temperature. They lie above the main sequence (luminosity class V in the Yerkes spectral classification) on the Hertzsp ...

on the

asymptotic giant branch The asymptotic giant branch (AGB) is a region of the Hertzsprung–Russell diagram populated by evolved cool luminous stars. This is a period of stellar evolution undertaken by all low- to intermediate-mass stars (about 0.5 to 8 solar masses) lat ...

with a

stellar classification 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 ...

of C6,5ea(Np), which indicates a carbon-rich atmosphere. It is a semi-regular pulsating star of the SRb type that is nearing the end of its fusing lifespan. A

sine curve A sine wave, sinusoidal wave, or sinusoid (symbol: ∿) is a periodic wave whose waveform (shape) is the trigonometric sine function. In mechanics, as a linear motion over time, this is '' simple harmonic motion''; as rotation, it correspon ...

fitted to the last ten pulsation cycles prior to 2017 give a pulsation period of 376 days with an

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 ...

of 0.75 magnitude. The star is shedding its outer atmosphere, and it is surrounded by a thin shell of dust and gas that was created during the most recent thermal pulse around 2,000 years ago. Observations have revealed a spiral structure in the material around the star. The spiral is suspected to be caused by an unseen companion star. The spiral windings are consistent with an

orbital period The orbital period (also revolution period) is the amount of time a given astronomical object takes to complete one orbit around another object. In astronomy, it usually applies to planets or asteroids orbiting the Sun, moons orbiting planets ...

of ~350 years.

Gallery

R Sculptoris A red giant sheds its skin.jpg, This image captures approximately 20x20 milliarcseconds. Curious spiral spotted by ALMA around red giant star R Sculptoris (data visualisation).jpg, Spiral spotted by

ALMA Alma or ALMA may refer to: Arts and entertainment * ''Alma'' (film), a 2009 Spanish short animated film * ''Alma'', an upcoming film by Sally Potter * ''Alma'' (Oswald de Andrade novel), 1922 * ''Alma'' (Le Clézio novel), 2017 * ''Alma'' ( ...

around the star (data visualisation). R Sculptoris and its hidden companion.jpg, R Sculptoris and its hidden companion, taken by

Hubble Space Telescope The Hubble Space Telescope (HST or Hubble) is a space telescope that was launched into low Earth orbit in 1990 and remains in operation. It was not the Orbiting Solar Observatory, first space telescope, but it is one of the largest and most ...

Gallery

References

Further reading