26074 Carlwirtz
Binary Mars-crosser and dynamical Hungaria asteroid.
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26074 Carlwirtz, first spotted as 1977 TD, is a small asteroid about 3 kilometers across that sits in the innermost part of the asteroid belt. It was discovered on October 8, 1977, by German astronomer Hans-Emil Schuster using the La Silla Observatory in northern Chile.
This object is both a dynamical Hungaria asteroid and a Mars-crosser, meaning its orbit crosses that of Mars. It is also likely a binary system, with a suspected moon, and it spins quickly, completing a rotation in about 2.5 hours. The asteroid was named in honor of German astronomer Carl Wilhelm Wirtz.
Its orbit is relatively circular, with low eccentricity, and it moves around the Sun at distances between 1.65 and 1.97 AU, taking about 890 days to complete one orbit. The orbital inclination is steep, at 32 degrees. While it belongs to the dynamical Hungaria group, it is not part of the Hungaria family itself; instead, it is a non-family asteroid from the main belt's background population.
Rotation period
In terms of physical makeup, Carlwirtz is thought to be an E-type asteroid, though it could also be a common S-type. Observations in June 2013 by Brian Warner at the Palmer Divide Station in California gave a well-defined rotation period of 2.5493 hours, with a brightness variation of 0.11 magnitudes. A follow-up in May 2018 produced a similar period of 2.539 hours.
Satellite
During the 2013 observations, Warner detected signs that Carlwirtz is likely a synchronous binary asteroid, with a moon orbiting it every 16.11 hours at an estimated distance of 6.1 kilometers. However, no eclipses or occultations were seen in either 2013 or 2018, and the lightcurve is classically bimodal. Because the asteroid's rotation period is close to two-thirds of an Earth day, single-station observations struggle to capture a full lightcurve.
Diameter and albedo
Estimates of its size vary. The Collaborative Asteroid Lightcurve Link, assuming an albedo of 0.30, calculates a diameter of 2.54 kilometers. Johnston's archive, using an albedo of 0.16, gives a larger diameter of 3.62 kilometers.
Background
26074 Carlwirtz orbits the Sun in the innermost asteroid belt at a distance of 1.65–1.97 AU once every 2 years and 5 months. Its orbit has an unusually low eccentricity of 0.09 and an inclination of 32° with respect to the ecliptic. It is a member of the Mars-crossing asteroids and also belongs to the dynamical Hungaria group, but is not a member of the Hungaria family, being a non-family asteroid of the main belt's background population. The body's observation arc begins at La Silla Observatory in October 1977, on the night following its official discovery observation.
The minor planet was named after Carl Wilhelm Wirtz (1875–1939), a German astronomer at Strasbourg and Kiel observatories. In 1924, he revealed statistically the redshift-distance relationship of spiral nebulae. The official naming citation was published by the Minor Planet Center on 28 September 2004.
Carlwirtz is an assumed E-type asteroid, but may as well be a common S-type asteroid. In June 2013, a rotational lightcurve obtained by American photometrist Brian Warner gave a well-defined rotation period of 2.5493 hours with a brightness amplitude of 0.11 magnitude.
Follow-up observations in May 2018 gave a similar period of 2.539 hours. During the 2013 observations, Warner also noted that Carlwirtz is likely a synchronous binary asteroid with a minor-planet moon of unknown size, having an orbital period of 16.11 hours and an estimated semi-major axis of 6.1 kilometers. No eclipsing or occultation events have been detected.
Frequently Asked Questions
What makes 26074 Carlwirtz's orbit unusual?
It carries a dual classification as both a dynamical Hungaria asteroid and a Mars-crosser, so its path actually intersects the orbit of Mars despite sitting in the inner belt. This makes it a useful object for studying how small bodies migrate near the inner asteroid-belt boundary.
How was 26074 Carlwirtz discovered?
German astronomer Hans-Emil Schuster first detected it on 8 October 1977 using instruments at the La Silla Observatory in northern Chile. At the time of discovery it was listed simply as 1977 TD before later receiving its permanent number and name.
Why do asteroid fans consider 26074 Carlwirtz noteworthy?
Its combination of a very fast rotation period, a suspected satellite, and a dual orbital classification (Hungaria plus Mars-crosser) makes it a rich case study for understanding how small inner-belt bodies evolve. It also stands as a permanent nod to Carl Wilhelm Wirtz's contributions to the field.
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Sources
Compiled from Wikipedia and the sources listed below. Text from Wikipedia is available under CC BY-SA 4.0; this entry is adapted from it.
- Wikipedia: 26074 Carlwirtz (CC BY-SA 4.0).
- Word definitions: the , each quoted from its Wikipedia article.
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