# 17246 Christophedumas

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Discovery [1] Orbit of Christophedumas LINEAR Lincoln Lab ETS 5 April 2000 (17246) Christophedumas Christophe Dumas (planetary scientist)[2] 2000 GL74 · 1973 VM main-belt · Koronis [3][4] Epoch 4 September 2017 (JD 2458000.5) Uncertainty parameter 0 45.84 yr (16,742 days) 2.9023 AU 2.7772 AU 2.8398 AU 0.0220 4.79 yr (1,748 days) 180.58° 0° 12m 21.6s / day 2.4444° 34.451° 229.77° 1[4][5][a] 4.5 km[6] 4.81 km (calculated)[3] 10 h[7] 0.21[4] S [3] 13.9[1][3]

17246 Christophedumas, provisional designation 2000 GL74, is a stony Koronian asteroid and binary system from the outer regions of the asteroid belt, approximately 4.6 kilometers in diameter.

It was discovered on 5 April 2000, by the LINEAR program at Lincoln Laboratory's Experimental Test Site near Socorro, New Mexico, United States.[2] It was named after planetary scientist Christophe Dumas. The asteroid's minor-planet moon was discovered in 2004.[4]

## Orbit and classification

3 Juno, the asteroid that Christophedumas will approach on 9 January 2129

Christophedumas is a member of the Koronis family, which is named after 158 Koronis. It orbits the Sun in the outer main-belt at a distance of 2.8–2.9 AU once every 4 years and 9 months (1,748 days). Its orbit has an eccentricity of 0.02 and an inclination of 2° with respect to the ecliptic.[1] The asteroid's observation arc begins 29 years prior to its official discovery observation, with a precovery taken at Palomar Observatory in April 1971.[2]

### Close approache with Juno

On 9 January 2129, Christophedumas will come within 3,639,998 kilometers of 3 Juno, one of the largest asteroids in the main-belt, and will pass it with a relative velocity of 6.597 km/s.[1]

## Physical characteristics

Christophedumas is a presumed stony S-type asteroid. With an albedo of 0.21, it is more reflective than most asteroids in the outer main-belt.[4] The Collaborative Asteroid Lightcurve Link adopts an albedo of 0.21 and calculates a diameter of 4.81 kilometers based on an absolute magnitude of 13.9.[3]

In December 2007, a rotational lightcurve of Christophedumas was obtained from photometric observations by Israeli astronomer David Polishook and colleagues. Lightcurve analysis gave a rotation period of 10 hours with a brightness amplitude of 0.15 magnitude (U=n.a.).[7] The team of astronomers also ruled out that Christophedumas might be an Escaping Ejecta Binary (EEB), that are thought to be created by fragments ejected from a disruptive impact event.[7]

## Moon

In 2004, a minor-planet moon, designated S/2004 (17246) 1, was discovered orbiting its primary, making Christophedumas a binary asteroid.[4][a] With a secondary-to-primary mean-diameter ratio of 0.22, the moon measures approximately 1 kilometer in diameter, based on a diameter of 4.5 kilometers for its primary.[6] While its rotation period and orbital eccentricity is not yet known, it is known that the moon completes one orbit every 90 days (2034 hours) with a semi-major axis of 228 kilometers.[5][6]

From the surface of Christophedumas, the moon would have an apparent diameter of about 0.668°, slightly larger than the Moon appears from Earth.[b]

## Naming

This minor planet was named after planetary scientist Christophe Dumas (born 1968), an observer of Solar System objects and expert in using adaptive optics. Dumas is a co-discoverer of the first asteroid moon imaged from Earth.[2] The approved naming citation was published by the Minor Planet Center on 29 September 1985 (M.P.C. 10060).[8]

## Notes

1. ^ a b IAUC 8293, S/2004 (17246) 1: reports the discovery on Jan. 14.9 UT, on six direct images (two sets of three images taken 20 min apart in time) made with the Hubble Space Telescope (+ ACS/HRC), of a satellite of minor planet (17246) 2000 GL_74 (V about 18.5). The satellite is clearly separated from the primary in five images. On Jan. 14.9195, the satellite was at separation 0".16 (projected separation 230 km) in p.a. 280 deg. Using the average albedo of the Koronis family (about 0.21), to which (17246) belongs, the size of the primary is estimated to be 4.5 km. The brightness difference is about 2 mag, giving an estimated diameter of the secondary of about 2 km.
Reported by: P. M. Tamblyn, Southwest Research Institute (SwRI) and Binary Astronomy; W. J. Merline, C. R. Chapman, D. Nesvorny, and D. D. Durda, SwRI; C. Dumas, Jet Propulsion Laboratory; A. D. Storrs, Towson University; L. M. Close, University of Arizona; and F. Menard, Observatoire de Grenoble
2. ^ Calculated by solving ${\displaystyle \scriptstyle {\mathrm {tan} \left({\frac {\theta }{2}}\right)={\frac {\mathrm {radius~of~moon} }{\mathrm {distance~from~surface~of~asteroid~to~center~of~moon} }}}}$.

## References

1. "JPL Small-Body Database Browser: 17246 Christophedumas (2000 GL74)" (2017-02-15 last obs.). Jet Propulsion Laboratory. Retrieved 5 July 2017.
2. ^ a b c d "17246 Christophedumas (2000 GL74)". Minor Planet Center. Retrieved 5 July 2017.
3. "LCDB Data for (17246)". Asteroid Lightcurve Database (LCDB). Retrieved 22 August 2016.
4. Tamblyn, P. M.; Merline, W. J.; Chapman, C. R.; Nesvorny, D.; Durda, D. D.; Dumas, C.; et al. (February 2004). "S/2004 (17246) 1". IAU Circular (8293). Bibcode:2004IAUC.8293....3T.
5. ^ a b Johnston, Wm. Robert (21 June 2016). "(17246) Christophedumas and S/2004 (17246) 1". Johnston's Archive. Retrieved 5 July 2017.
6. ^ a b c Durda, D. D.; Enke, B. L.; Merline, W. J.; Richardson, D. C.; Asphaug, E.; Bottke, W. F. (March 2010). "Comparing the Properties of Observed Main-Belt Asteroid Binaries and Modeled Escaping Ejecta Binaries (EEBs) from Numerical Simulations" (PDF). 41st Lunar and Planetary Science Conference: 2558. Bibcode:2010LPI....41.2558D. Retrieved 5 July 2017.
7. ^ a b c Polishook, D.; Brosch, N.; Prialnik, D. (March 2011). "Rotation periods of binary asteroids with large separations – Confronting the Escaping Ejecta Binaries model with observations" (PDF). Icarus. 212 (1): 167–174. Bibcode:2011Icar..212..167P. arXiv:. doi:10.1016/j.icarus.2010.12.020. Retrieved 5 July 2017.
8. ^ "MPC/MPO/MPS Archive". Minor Planet Center. Retrieved 5 July 2017.