HL Tau 76 is a variable

white dwarf A white dwarf is a Compact star, stellar core remnant composed mostly of electron-degenerate matter. A white dwarf is very density, dense: in an Earth sized volume, it packs a mass that is comparable to the Sun. No nuclear fusion takes place i ...

star A star is a luminous spheroid of plasma (physics), plasma held together by Self-gravitation, self-gravity. The List of nearest stars and brown dwarfs, nearest star to Earth is the Sun. Many other stars are visible to the naked eye at night sk ...

of the DAV (or ZZ Ceti) type. It was observed by

G. Haro Guillermo Haro Barraza (; 21 March 1913 – 26 April 1988) was a Mexican astronomer. Through his own astronomical research and the formation of new institutions, Haro was influential in the development of modern observational astronomy in M ...

and

W. J. Luyten Willem Jacob Luyten (March 7, 1899 – November 21, 1994) was a Dutch-American astronomer. "Willem Jacob Luyten", ''Marquis Who's Who'', 2006. Life Jacob Luyten was born in Semarang, Java, at the time part of the Dutch East Indies. His ...

in 1961, and was the first variable

discovered when, in 1968, Arlo U. Landolt found that it varied in brightness with a period of approximately 749.5 seconds, or 12.5 minutes. Like other DAV white dwarfs, its variability arises from non-radial

gravity wave In fluid dynamics, gravity waves are waves in a fluid medium or at the interface between two media when the force of gravity or buoyancy tries to restore equilibrium. An example of such an interface is that between the atmosphere and the oc ...

pulsations within itself.^{, § 7.} Later observation and analysis has found HL Tau 76 to pulsate in over 40 independent

vibrational mode A normal mode of a dynamical system is a pattern of motion in which all parts of the system move sinusoidally with the same frequency and with a fixed phase relation. The free motion described by the normal modes takes place at fixed frequencies. ...

s, with periods between 380

second The second (symbol: s) is a unit of time derived from the division of the day first into 24 hours, then to 60 minutes, and finally to 60 seconds each (24 × 60 × 60 = 86400). The current and formal definition in the International System of U ...

s and 1390 seconds. The designation HL Tau 76 derives from the discovery of this star as a white dwarf, when it was described as ''Taurus no.76'' in a publication authored by

Guillermo Haro Guillermo Haro Barraza (; 21 March 1913 – 26 April 1988) was a Mexican astronomer. Through his own astronomical research and the formation of new institutions, Haro was influential in the development of modern observational astronomy in M ...

and

Willem Jacob Luyten Willem Jacob Luyten (March 7, 1899 – November 21, 1994) was a Dutch-American astronomer. "Willem Jacob Luyten", ''Marquis Who's Who'', 2006. Life Jacob Luyten was born in Semarang, Java, at the time part of the Dutch East Indies. His ...

. The exact designation ''HL Tau 76'' was then used in subsequent papers, including one giving the star its designation EGGR 265 where it was noted to be variable. It was then included in the 57th name-list of variable stars and given the

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 ...

V441 Tauri. The unusual designation HL Tau 76 continues to be used by most authors.

Notes and references

{{DEFAULTSORT:HL Tau 76 Taurus (constellation) Pulsating white dwarfs Tauri, V411