26074 Carlwirtz
Discovery [1]
Discovered byH.-E. Schuster
Discovery siteLa Silla Obs.
Discovery date8 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 arc40.83 yr (14,913 d)
Aphelion1.9722 AU
Perihelion1.6499 AU
1.8110 AU
Eccentricity0.0890
2.44 yr (890 d)
198.66°
0° 24m 15.84s / day
Inclination31.613°
102.81°
73.302°
Known satellites1 (D: n.a. km; P: 16.11 h)[4][lower-alpha 1]
Earth MOID0.7534 AU (294 LD)
Physical characteristics
Mean diameter
2.54 km (est.)[3]
3.62 km (est.)[4]
2.5493±0.0003 h[5][lower-alpha 1]
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]

    Orbit and classification

    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]

    Naming

    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]

    Physical characteristics

    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.

    Rotation period

    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][lower-alpha 1] Follow-up observations by Warner in May 2018 gave a similar period 2.539±0.002 hours (U=2+).[3][lower-alpha 2]

    Satellite

    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][lower-alpha 1] 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][lower-alpha 1][lower-alpha 2]

    Diameter and albedo

    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.

    Notes

    1. 1 2 3 4 5 Lightcurve plot of (26074) Carlwirtz Warner (2013), at the Palmer Divide Station (U82). Primary rotation period: 2.5493±0.0003 hours. Secondary rotation period: 16.11±0.02 hours. Quality code is 3. Summary figures at the LCDB and CS3 website.
    2. 1 2 Warner (2018). Lightcurve plot of follow-up observation from May 2018 Quality code is 2+. Summary figures at the LCDB and CS3 website.

    References

    1. 1 2 3 4 5 6 7 "26074 Carlwirtz (1977 TD)". Minor Planet Center. Retrieved 19 November 2018.
    2. 1 2 3 4 "JPL Small-Body Database Browser: 26074 Carlwirtz (1977 TD)" (2018-08-07 last obs.). Jet Propulsion Laboratory. Retrieved 19 November 2018.
    3. 1 2 3 4 5 6 7 8 9 10 11 "LCDB Data for (26074) Carlwirtz". Asteroid Lightcurve Database (LCDB). Retrieved 19 November 2018.
    4. 1 2 3 4 5 Johnston, Wm. Robert (21 September 2014). "Asteroids with Satellites Database – (26074) Carlwirtz". Johnston's Archive. Retrieved 19 November 2018.
    5. 1 2 3 4 5 6 Warner, Brian D. (October 2013). "Asteroid Lightcurve Analysis at CS3-Palmer Divide Station: 2013 May-June". The Minor Planet Bulletin. 40 (4): 208–212. Bibcode:2013MPBu...40..208W. ISSN 1052-8091. Retrieved 19 November 2018.
    6. 1 2 "Asteroid 26074 Carlwirtz". Small Bodies Data Ferret. Retrieved 19 November 2018.
    7. ↑ "Asteroid (26074) Carlwirtz". AstDyS-2, Asteroids – Dynamic Site. Retrieved 25 May 2018.
    8. ↑ "MPC/MPO/MPS Archive". Minor Planet Center. Retrieved 19 November 2018.
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