2430 Bruce Helin

2430 Bruce Helin (prov. designation: 1977 VC) is a stony Phocaea asteroid and slow rotator from the inner regions of the asteroid belt. It was discovered by American astronomers Eleanor Helin and Eugene Shoemaker at the U.S. Palomar Observatory in California, on 8 November 1977.[9] It was later named after Bruce Helin, son of the first discoverer.[2] The S-type asteroid (Sl) has an exceptionally long rotation period of 128 hours and measures approximately 12 kilometers (7.5 miles) in diameter.

2430 Bruce Helin
Bruce Helin modeled from its lightcurve
Discovery [1]
Discovered byE. F. Helin
E. Shoemaker
Discovery sitePalomar Obs.
Discovery date8 November 1977
Designations
(2430) Bruce Helin
Named after
Bruce Helin [2]
(son of Eleanor Helin)
1977 VC · 1976 JU1
A908 WC
main-belt · Phocaea [3][4]
Orbital characteristics [1]
Epoch 4 September 2017 (JD 2458000.5)
Uncertainty parameter 0
Observation arc40.44 yr (14,772 days)
Aphelion2.8697 AU
Perihelion1.8555 AU
2.3626 AU
Eccentricity0.2146
3.63 yr (1,326 days)
21.845°
0° 16m 17.04s / day
Inclination23.459°
45.854°
309.89°
Physical characteristics
Mean diameter
128 h[lower-alpha 1]
129.4163±0.3970 h[7]
129.75 h[8]
  • 0.175±0.006[5]
  • 0.238±0.032[6]
11.693±0.003 (R)[7] · 11.70[6] · 11.8[1][3] · 12.24[5]

    Orbit and classification

    Bruce Helin is a member of the Phocaea family (701).[4] It orbits the Sun in the inner main-belt at a distance of 1.9–2.9 AU once every 3 years and 8 months (1,326 days). Its orbit has an eccentricity of 0.21 and an inclination of 23° with respect to the ecliptic.[1] It was first observed at A908 WC at Heidelberg Observatory in 1908. The body's observation arc begins with a precovery taken at Crimea–Nauchnij in 1976, or one year prior to its official discovery observation at Palomar.[9]

    Naming

    This minor planet was named after Bruce Helin, son of the first discover Eleanor Helin, in an expression of gratitude for "the many years he tolerated his mother's preoccupation with extraterrestrial objects".[2] The discoverer has also honoured her daughter-in-law and wife of Bruce, Nancy Coker Helin, by the minor planet 4222 Nancita.[10] The official naming citation was published by the Minor Planet Center on 13 October 1981 (M.P.C. 6421).[11]

    Physical characteristics

    In the Tholen classification, Bruce Helin is a common, stony S-type asteroid, while in the Bus–Binzel SMASS taxonomy, it is an Sl-subtype, which transitions from the S-type to the uncommon L-type asteroid.[1]

    Rotation period

    The first rotational lightcurve of Bruce Helin was obtained from photometric observations by Czech astronomer Petr Pravec in September 2006. The lightcurve showed a rotation period of 128 hours with a brightness variation of 0.60 in magnitude (U=2).[lower-alpha 1] Later observations rendered a similar rotation period of 129.75 and 129.4163±0.3970 hours, respectively (U=n.a./2).[8][7]

    Diameter and albedo

    According to the surveys carried out by the Japanese Akari satellite and NASA's Wide-field Infrared Survey Explorer with its NEOWISE mission, Bruce Helin measures 11.8 and 12.5 kilometers in diameter, and its surface has an albedo of 0.18 and 0.24, respectively.[5][6] The Collaborative Asteroid Lightcurve Link (CALL) assumes an albedo of 0.23 and calculates a diameter of 12.1 kilometers with an absolute magnitude of 11.8.[3]

    Notes
    1. Pravec (2006) web: rotation period 128 hours with a brightness amplitude of 0.6 mag. Summary figures at Collaborative Asteroid Lightcurve Link (CALL) for (2430) Bruce Helin

    References
    1. "JPL Small-Body Database Browser: 2430 Bruce Helin (1977 VC)" (2016-10-11 last obs.). Jet Propulsion Laboratory. Retrieved 3 July 2017.
    2. Schmadel, Lutz D. (2007). "(2430) Bruce Helin". Dictionary of Minor Planet Names. Springer Berlin Heidelberg. p. 198. doi:10.1007/978-3-540-29925-7_2431. ISBN 978-3-540-00238-3.
    3. "LCDB Data for (2430) Bruce Helin". Asteroid Lightcurve Database (LCDB). Retrieved 2 May 2016.
    4. "Asteroid 2430 Bruce Helin – Nesvorny HCM Asteroid Families V3.0". Small Bodies Data Ferret. Retrieved 26 October 2019.
    5. Usui, Fumihiko; Kuroda, Daisuke; Müller, Thomas G.; Hasegawa, Sunao; Ishiguro, Masateru; Ootsubo, Takafumi; et al. (October 2011). "Asteroid Catalog Using Akari: AKARI/IRC Mid-Infrared Asteroid Survey". Publications of the Astronomical Society of Japan. 63 (5): 1117–1138. Bibcode:2011PASJ...63.1117U. doi:10.1093/pasj/63.5.1117. Retrieved 17 October 2019. (online, AcuA catalog p. 153)
    6. Masiero, Joseph R.; Mainzer, A. K.; Grav, T.; Bauer, J. M.; Cutri, R. M.; Nugent, C.; et al. (November 2012). "Preliminary Analysis of WISE/NEOWISE 3-Band Cryogenic and Post-cryogenic Observations of Main Belt Asteroids". The Astrophysical Journal Letters. 759 (1): 5. arXiv:1209.5794. Bibcode:2012ApJ...759L...8M. doi:10.1088/2041-8205/759/1/L8. Retrieved 2 May 2016.
    7. Waszczak, Adam; Chang, Chan-Kao; Ofek, Eran O.; Laher, Russ; Masci, Frank; Levitan, David; et al. (September 2015). "Asteroid Light Curves from the Palomar Transient Factory Survey: Rotation Periods and Phase Functions from Sparse Photometry". The Astronomical Journal. 150 (3): 35. arXiv:1504.04041. Bibcode:2015AJ....150...75W. doi:10.1088/0004-6256/150/3/75. Retrieved 2 May 2016.
    8. Hanus, J.; Broz, M.; Durech, J.; Warner, B. D.; Brinsfield, J.; Durkee, R.; et al. (November 2013). "An anisotropic distribution of spin vectors in asteroid families". Astronomy and Astrophysics. 559: 19. arXiv:1309.4296. Bibcode:2013A&A...559A.134H. doi:10.1051/0004-6361/201321993. Retrieved 2 May 2016.
    9. "2430 Bruce Helin (1977 VC)". Minor Planet Center. Retrieved 2 May 2016.
    10. Schmadel, Lutz D. (2007). "(4222) Nancita". Dictionary of Minor Planet Names. Springer Berlin Heidelberg. p. 361. doi:10.1007/978-3-540-29925-7_4187. ISBN 978-3-540-29925-7.
    11. "MPC/MPO/MPS Archive". Minor Planet Center. Retrieved 2 May 2016.
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