QZ Aurigae

Lore & Background

QZ Aurigae was discovered by Nicholas Sanduleak on an objective prism photographic plate taken at the Warner and Swasey Observatory on 4 November 1964. Examination of pre-discovery plates from Sonneberg Observatory showed that the eruption occurred in early February 1964, with a photographic magnitude of 6.0 on 14 February 1964. Its brightness declined in images taken after the 14th, suggesting its peak brightness was above 6.0, and it was probably visible to the naked eye for a short time.

As a nova, QZ Aurigae is a binary system consisting of a donor star orbiting a white dwarf. The stars are so close that matter from the donor star transfers to an accretion disk surrounding the white dwarf. Because the separation between the stars is comparable to the radius of the donor star, novae are often eclipsing binaries, and QZ Aurigae shows such eclipses. The depth of the eclipses, 1.2 magnitudes in blue light, is unusually large, indicating that both the white dwarf and the inner accretion disk are fully occulted at mid eclipse.

The orbital period is 8.58 hours. Schaeffer used small changes in the orbital period, along with other observational data, to derive a mass for the white dwarf and for the donor star, as well as a mass transfer rate per year. The donor star is a red dwarf with a spectral type of K1.

Reader's Guide

QZ Aurigae is significant as a fast nova that dropped from peak brightness by three magnitudes in less than 100 days, a defining characteristic of its classification. Its discovery by Nicholas Sanduleak in 1964, with pre-eruption data from Sonneberg Observatory, provides a well-documented timeline of the eruption, including a probable naked-eye visibility period. The system's unusually deep eclipses—1.2 magnitudes in blue light—are a key feature, as they fully occult both the white dwarf and the inner accretion disk, offering a rare opportunity to study the structure of such systems. The measured orbital period of 8.58 hours and the derived masses and mass transfer rate from Schaeffer's work contribute to the understanding of nova binary dynamics. The donor star's spectral type of K1 further characterizes the system. As an eclipsing binary, QZ Aurigae serves as an important object for studying the interaction between the donor star and the white dwarf, particularly the accretion process and the behavior of the accretion disk during and after a nova eruption.

Did You Know?

• Its peak brightness was probably above photographic magnitude 6.0.
• The eclipses are 1.2 magnitudes deep in blue light, fully occulting the white dwarf and inner accretion disk.

Position in the Naming Sequence

QZ Aurigae occupies a spot near the very end of the double-letter portion of the variable star designation scheme. Once the single letters R through Z are exhausted within a given constellation, the system advances to paired combinations: RR through RZ, then SS through SZ, TT through TZ, and onward through the alphabet until it reaches QZ. At that point the letter-based method is abandoned entirely, and subsequent stars receive identifiers of the form V335, V336, and so forth. This means QZ Aurigae belongs to a constellation in which at least 333 other variable stars had already been catalogued before it received its own label. The trailing word Aurigae is the Latin genitive of the constellation Auriga, following the same grammatical convention that turns Centaurus into Centauri or Orion into Orionis. Together, the letter pair and the genitive form constitute a complete, unambiguous identifier within the broader Bayer-style naming tradition.

Structural Rules Behind the Label

The designation QZ Aurigae is shaped by several structural constraints that keep the naming system orderly yet limited. The letter J is excluded from both the first and second positions, shrinking the available pool of pairings. Furthermore, the second letter can never fall before the first in alphabetical order, which rules out combinations such as BA, CA, CB, or DA. This ordering rule guarantees a logical, non-repeating progression through the sequence. Under these restrictions the total number of valid two-letter combinations reaches exactly 334, after which the system hands off to the V-number format. QZ therefore sits among the last letter-pair identifiers available before that handoff, marking it as a relatively late entry in any constellation's variable-star roster. The entire scheme extends the well-known Bayer designation format by prepending a unique identifier to the constellation's Latin genitive name, producing a label that is both systematic and immediately locatable.

Historical Roots of the Convention

The naming framework that ultimately produced the label QZ Aurigae was devised by Friedrich W. Argelander in the early nineteenth century, when only a small handful of variable stars were known and single Latin letters appeared more than adequate. Argelander deliberately selected R as the starting letter to sidestep confusion with existing Bayer designations or spectral-type labels, despite a widespread but incorrect belief that he chose it for its connection to the German rot or French rouge, both meaning red. By 1836 the letter S had been applied in only one constellation, Serpens. The arrival of photographic astronomy rapidly multiplied the number of known variables, driving the system past its single-letter phase and into double-letter combinations. Two subsequent supplementary double-lettering schemes eventually struck the same alphabetical ceiling, compelling the introduction of the V-number system. Catalogues published by Chambers in 1865, Schönfeld in 1866, and Chandler's successive updates through 1896 all relied on this evolving framework.

Modern Custodianship and Cataloguing

The assignment of designations like QZ Aurigae now rests under the authority of the International Astronomical Union, which since 1946 has delegated the practical work to the Sternberg Astronomical Institute and the Institute of Astronomy of the Russian Academy of Sciences in Moscow. Sternberg maintains the General Catalogue of Variable Stars, a register that is amended roughly every two years through the release of a new Name-List. A concrete illustration is the December 2011 publication of the 80th Name-List, Part II, which assigned designations to 2,161 newly discovered variables and pushed the GCVS total to 45,678 entries. Among those fresh designations were stars in Auriga, Centaurus, and Corona Borealis, demonstrating that the system continues to expand. Before the IAU's current arrangement took hold, the German Astronomical Society had shouldered the responsibility of maintaining variable-star identifiers through annual updates published in the Astronomische Nachrichten journal.