4029 Bridges

4029 Bridges, provisional designation 1982 KC1, is a stony asteroid and binary system from the middle regions of the asteroid belt, approximately 8 kilometers in diameter.

4029 Bridges
Discovery [1]
Discovered byC. Shoemaker
Discovery sitePalomar Obs.
Discovery date24 May 1982
Designations
(4029) Bridges
Named after
Patricia M. Bridges
(planetary cartographer)[2]
1982 KC1 · 1974 HS2
1975 TQ · 1978 AF
1978 JJ2 · 1982 OX
1986 JF
main-belt · (middle) [3]
Orbital characteristics [1]
Epoch 4 September 2017 (JD 2458000.5)
Uncertainty parameter 0
Observation arc42.93 yr (15,680 days)
Aphelion2.8575 AU
Perihelion2.1925 AU
2.5250 AU
Eccentricity0.1317
4.01 yr (1,466 days)
287.79°
0° 14m 44.16s / day
Inclination5.4383°
214.78°
16.729°
Known satellites1[4][5][lower-alpha 1]
(D: 1.87 km; P: 16.317 h)
Physical characteristics
Dimensions7.433±0.122 km[6]
7.91 km[7]
8.015±0.073 km[8]
3.57459±0.0001 h[9]
3.5746±0.0001 h[5]
3.5748±0.0002 h[10]
3.57491±0.0003 h[lower-alpha 2]
3.6941±0.0002 h[11]
0.1848[7]
0.2007±0.0148[8]
0.265±0.036[6]
S [12][3]
12.40±0.10 (R)[9] · 12.49±0.02 (R)[lower-alpha 2] · 12.8[1] · 12.85[8] · 12.96±0.094[3][7] · 13.03±0.50[12]

    It was discovered on 24 May 1982, by American astronomer Carolyn Shoemaker at Palomar Observatory, California, and named after American USGS planetary cartographer Patricia M. Bridges.[2][13]

    Orbit and classification

    Bridges is a stony S-type asteroid that orbits the Sun in the middle main-belt at a distance of 2.2–2.9 AU once every 4.01 years (1,466 days). Its orbit has an eccentricity of 0.13 and an inclination of 5° with respect to the ecliptic.[1] With a semi-major axis of 2.525 AU, Bridges is near the main-belt's Kirkwood gap at 2.5 AU, which corresponds to the 3:1 orbital resonance with the gas giant Jupiter. It is, however, not a member of the Alinda family due to its much lower eccentricity.

    It was first identified as 1974 HS2 at the Chilean Cerro El Roble Observatory in 1974, extending the body's observation arc by 8 years prior to its official discovery observation at Palomar.[13]

    Physical characteristics

    Primary

    Rotation period

    In May 2002, a first rotational lightcurve of Bridges was obtained from photometric observations by French amateur astronomers René Roy and Laurent Bernasconi. Lightcurve analysis gave a well-defined rotation period of 3.6941 hours with a brightness variation of 0.24 magnitude (U=3).[11]

    A large number of observations have followed since 2006, when a satellite in orbit of Bridges was discovered (see below).[lower-alpha 1] Between 2007 and 2012, several observation by astronomers Petr Pravec and gave a period between 3.57459 and 3.5754 hours with an amplitude between 0.18 and 0.29 magnitude (U=3/3/3/3/3).[9][10][lower-alpha 3][lower-alpha 4][lower-alpha 5][lower-alpha 2]

    Diameter and albedo

    According to the survey carried out by NASA's Wide-field Infrared Survey Explorer (WISE) with its subsequent NEOWISE mission, Bridges measures 7.433 and 8.015 kilometers in diameter and its surface has an albedo of 0.265 and 0.2007, respectively.[6][8] The Collaborative Asteroid Lightcurve Link adopts Petr Pravec's revised WISE-data, that is, an albedo of 0.1848 and a diameter of 7.91 kilometers with an absolute magnitude of 12.96.[3][7]

    Satellite

    In April and May 2006, Bridges was observed by astronomers David Higgins at Hunters Hill Observatory (E14), Australia, Petr Pravec and Peter Kušnirák at Ondřejov Observatory Czech Republic, Walter R. Cooney Jr., John Gross and Dirk Terrell at Sonoita Research Observatory (G94), United States, and Robert Stephens at Santana Observatory (646), United States.[lower-alpha 1]

    The observed mutual occultation/eclipsing events revealed, that Bridges is a binary asteroid, that is orbited every 16.31±0.01 hours by a minor-planet moon.[5][lower-alpha 1] A refined orbital period of 16.317 hours was later published.[3][9] Based on the system's secondary-to-primary mean-diameter ratio of 0.24±0.02,[5] the satellite measures approximately 1.87±0.16 kilometers in diameter.[4] Johnston's Archive also estimates a semi-major axis of 13 kilometers for the moon's orbit.[4]

    Naming

    This minor planet was named after Patricia M. Bridges, planetary cartographer with the United States Geological Survey. Bridges has created detailed maps of several planetary body's surface features, and has been an airbrushing expert for shaded lunar relief maps based on spacecraft images.[2] The approved naming citation was published by the Minor Planet Center on 12 December 1989 (M.P.C. 15576).[14]

    Notes
    1. Central Bureau for Astronomical Telegrams – CBET No. 507 for (4029) Bridges, 8 May 2006:
      Photometric observation taken between 11 April and 4 May 2006, revealed that (4029) Bridges is a binary system. Its satellite has an orbital period of 16.31±0.01 hours. The primary has a rotation period of 3.5746±0.0001 hours and a brightness amplitude of 0.20 magnitude. The observed mutual occultation/eclipsing events are 0.06 to 0.12 magnitude deep. The system has a secondary-to-primary mean-diameter ratio of 0.24±0.02
      Reported by: D. Higgins, Canberra, Australia; P. Pravec and P. Kusnirak, Ondrejov Observatory; W. Cooney, J. Gross, and D. Terrell, Sonoita Research Observatory, Sonoita, AZ; and R. Stephens, Yucca Valley, CA.
    2. (4029) Bridges – unpublished photometry at Ondřejov Observatory. Credits: Ondrejov; date: 16 Oct 2011 – 1 Nov 2011; period: 3.57491±0.00009; amplitude 0.23
    3. (4029) Bridges – unpublished photometry at Ondřejov Observatory. Credits: CarbuncleH,Ond,SPles; date: 5 Oct 2007 – 12 Nov 2007; period: 3.5752±0.0001; amplitude 0.21: Remarks: P_orb = 16.31 +/- 0.02 h, a lower limit on D_2/D_1 = 0.32 +/- 0.02. H_R estimated assuming G = 0.24 +/- 0.11
    4. (4029) Bridges – unpublished photometry at Ondřejov Observatory. Credits: HuntersH,Prompt; date: 8–19 May 2010; period: 3.5754±0.0002; amplitude 0.23
    5. (4029) Bridges – unpublished photometry at Ondřejov Observatory. Credits: HuntersH, Prompt, Khar; date: 4–9 June 2010 ; period: 3.5752±0.0002; amplitude 0.29
    gollark: Sure, but people do in the Empire still do, well, work.
    gollark: I mean, if I remember correctly you can just build ones without volition or something, and have them do basically the same stuff.
    gollark: What jobs can sophont AIs do that nonsophont ones *can't*?
    gollark: You can get 1TB microSD cards now. Imagine the density of a bucket of those.
    gollark: It should switch to one system, and be less confusing.

    References
    1. "JPL Small-Body Database Browser: 4029 Bridges (1982 KC1)" (2017-03-29 last obs.). Jet Propulsion Laboratory. Retrieved 4 July 2017.
    2. Schmadel, Lutz D. (2007). "(4029) Bridges". Dictionary of Minor Planet Names – (4029) Bridges. Springer Berlin Heidelberg. p. 344. doi:10.1007/978-3-540-29925-7_4012. ISBN 978-3-540-00238-3.
    3. "LCDB Data for (4029) Bridges". Asteroid Lightcurve Database (LCDB). Retrieved 6 April 2017.
    4. Johnston, Robert. "(4029) Bridges". johnstonsarchive.net. Retrieved 6 April 2017.
    5. Higgins, D.; Pravec, P.; Kusnirak, P.; Cooney, W.; Gross, J.; Terrell, D.; et al. (May 2006). "(4029) Bridges". Central Bureau Electronic Telegrams. 507 (507): 1. Bibcode:2006CBET..507....1H. Retrieved 6 April 2017.
    6. Masiero, Joseph R.; Grav, T.; Mainzer, A. K.; Nugent, C. R.; Bauer, J. M.; Stevenson, R.; et al. (August 2014). "Main-belt Asteroids with WISE/NEOWISE: Near-infrared Albedos". The Astrophysical Journal. 791 (2): 11. arXiv:1406.6645. Bibcode:2014ApJ...791..121M. doi:10.1088/0004-637X/791/2/121. Retrieved 6 April 2017.
    7. Pravec, Petr; Harris, Alan W.; Kusnirák, Peter; Galád, Adrián; Hornoch, Kamil (September 2012). "Absolute magnitudes of asteroids and a revision of asteroid albedo estimates from WISE thermal observations". Icarus. 221 (1): 365–387. Bibcode:2012Icar..221..365P. doi:10.1016/j.icarus.2012.07.026. Retrieved 6 April 2017.
    8. Mainzer, A.; Grav, T.; Masiero, J.; Hand, E.; Bauer, J.; Tholen, D.; et al. (November 2011). "NEOWISE Studies of Spectrophotometrically Classified Asteroids: Preliminary Results". The Astrophysical Journal. 741 (2): 25. arXiv:1109.6407. Bibcode:2011ApJ...741...90M. doi:10.1088/0004-637X/741/2/90.
    9. Pravec, P.; Scheirich, P.; Vokrouhlický, D.; Harris, A. W.; Kusnirák, P.; Hornoch, K.; et al. (March 2012). "Binary asteroid population. 2. Anisotropic distribution of orbit poles of small, inner main-belt binaries". Icarus. 218 (1): 125–143. Bibcode:2012Icar..218..125P. doi:10.1016/j.icarus.2011.11.026. Retrieved 6 April 2017.
    10. Higgins, David; Oey, Julian; Pravec, Petr (January 2011). "Period Determination of Binary Asteroid Targets Observed at Hunters Hill Observatory: May-September 2009". The Minor Planet Bulletin. 38 (1): 46–49. Bibcode:2011MPBu...38...46H. ISSN 1052-8091. Retrieved 6 April 2017.
    11. Behrend, Raoul. "Asteroids and comets rotation curves – (4029) Bridges". Geneva Observatory. Retrieved 6 April 2017.
    12. Veres, Peter; Jedicke, Robert; Fitzsimmons, Alan; Denneau, Larry; Granvik, Mikael; Bolin, Bryce; et al. (November 2015). "Absolute magnitudes and slope parameters for 250,000 asteroids observed by Pan-STARRS PS1 - Preliminary results". Icarus. 261: 34–47. arXiv:1506.00762. Bibcode:2015Icar..261...34V. doi:10.1016/j.icarus.2015.08.007. Retrieved 6 April 2017.
    13. "4029 Bridges (1982 KC1)". Minor Planet Center. Retrieved 6 April 2017.
    14. "MPC/MPO/MPS Archive". Minor Planet Center. Retrieved 6 April 2017.
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