| Discovery [1] | |
|---|---|
| Discovered by | H.-E. Schuster |
| Discovery site | La Silla Obs. |
| Discovery date | 8 October 1977 |
| Designations | |
| (26074) Carlwirtz | |
Named after | Carl Wilhelm Wirtz [1] (German astronomer) |
| 1977 TD ·1996 KH | |
| Mars-crosser [2] · Hungaria [1] binary [3] [4] | |
| Orbital characteristics [2] | |
| Epoch 27 April 2019 (JD 2458600.5) | |
| Uncertainty parameter 0 | |
| Observation arc | 40.83 yr (14,913 d) |
| Aphelion | 1.9722 AU |
| Perihelion | 1.6499 AU |
| 1.8110 AU | |
| Eccentricity | 0.0890 |
| 2.44 yr (890 d) | |
| 198.66° | |
| 0° 24m 15.84s / day | |
| Inclination | 31.613° |
| 102.81° | |
| 73.302° | |
| Known satellites | 1 (D: n.a. km; P: 16.11 h) [4] [a] |
| Earth MOID | 0.7534 AU (294 LD) |
| Physical characteristics | |
| 2.54 km (est.) [3] 3.62 km (est.) [4] | |
| 2.5493±0.0003 h [5] [a] | |
| 0.16(assumed) [4] 0.30(assumed) [3] | |
| E (assumed) [3] | |
| 14.9 [3] 15.0 [1] [2] | |
26074 Carlwirtz (provisional designation 1977 TD) is a dynamical Hungaria asteroid and binary Mars-crosser from the innermost regions of the asteroid belt, approximately 3 kilometers (2 miles) in diameter. It was discovered on 8 October 1977, by German astronomer Hans-Emil Schuster at ESO's La Silla Observatory in northern Chile. The likely binary asteroid on a relatively circular orbit has a short rotation period of 2.5 hours. [3] It was named for German astronomer Carl Wilhelm Wirtz. [1] The system's suspected minor-planet moon of unknown size was first detected in 2013. [5]
Carlwirtz is a member of the Mars-crossing asteroids, a dynamically unstable group between the main belt and the near-Earth populations, crossing the orbit of Mars at 1.66 AU. [1] [6] It also belongs to the dynamical Hungaria group, which forms the innermost dense concentration of asteroids in the Solar System. [3] It is, however, not a member of the Hungaria family ( 003 ), but a non-family asteroid of the main belt's background population when applying the hierarchical clustering method to its proper orbital elements. [6] [7]
It orbits the Sun in the innermost asteroid belt at a distance of 1.65–1.97 AU once every 2 years and 5 months (890 days; semi-major axis of 1.81 AU). Its orbit has an unusually low eccentricity of 0.09 and an inclination of 32° with respect to the ecliptic. [2] The body's observation arc begins at La Silla Observatory in October 1977, on the night following its official discovery observation. [1]
This 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 ( M.P.C. 52769). [8]
Carlwirtz is an assumed E-type asteroid, [3] but may as well be a common S-type asteroid, since the E-type is typical found among members of the Hungaria family rather than among the larger, encompassing dynamical group with the same name.
In June 2013, a rotational lightcurve of Carlwirtz was obtained from photometric observations by American photometrist Brian Warner at the Palmer Divide Station ( U82 ) in California. Lightcurve analysis gave a well-defined rotation period of 2.5493±0.0003 hours with a brightness amplitude of 0.11±0.01 magnitude ( U=3 ). [5] [a] Follow-up observations by Warner in May 2018 gave a similar period 2.539±0.002 hours ( U=2+ ). [3] [b]
During the observations in June 2013, Warner also noted that Carlwirtz is likely a synchronous binary asteroid with a minor-planet moon in its orbit. [5] [a] While the satellite dimension could not be determined, it has an orbital period of 16.11 hours with an estimated semi-major axis of 6.1 kilometers. [4] However, neither in 2013 nor in the 2018-observations any eclipsing/occultation events could be detected. Instead the asteroid has a classically shaped bimodal lightcurve instead. Since Carlwirtz has a period that is close to two thirds of an Earth-day, single-station observations have difficulties to track a complete lightcurve. [3] [5] [a] [b]
The Collaborative Asteroid Lightcurve Link assumes an albedo of 0.30 – a compromise value between the S-type (0.20) and E-type (0.40) asteroids – and calculates a diameter of 2.54 kilometers based on an absolute magnitude of 14.9. [3] [5] According to estimates by Johnston's archive, Carlwirtz measures 3.62 kilometers in diameter for an assumed albedo of 0.16.
