1319 Disa

1319 Disa, provisional designation 1934 FO, is a carbonaceous asteroid from the outer region of the asteroid belt, approximately 25 kilometers in diameter. It was discovered on 19 March 1934, by English-born, South African astronomer Cyril Jackson at Johannesburg Observatory in South Africa.[12] It is named for the orchid Disa.[3]

1319 Disa
Discovery[1]
Discovered byC. Jackson
Discovery siteJohannesburg Obs.
Discovery date19 March 1934
Designations
(1319) Disa
Pronunciation/ˈdaɪsə/[2]
Named after
Disa (orchid – flowering plant)[3]
1934 FO · 1929 GE
1970 FM · A908 EA
main-belt · (outer)[4]
Orbital characteristics[1]
Epoch 4 September 2017 (JD 2458000.5)
Uncertainty parameter 0
Observation arc109.20 yr (39,885 days)
Aphelion3.6026 AU
Perihelion2.3684 AU
2.9855 AU
Eccentricity0.2067
5.16 yr (1,884 days)
41.069°
0° 11m 27.96s / day
Inclination2.8007°
256.10°
316.25°
Physical characteristics
Dimensions16.88±1.12 km[5]
24.00±0.37 km[6]
25.651±0.321 km[7]
25.894±0.180 km[8]
40.33 km (calculated)[4]
7.080±0.003 h[9][lower-alpha 1]
7.082±0.001 h[10]
7.0820±0.0077 h[11]
0.057 (assumed)[4]
0.0959±0.0034[8]
0.097±0.012[7]
0.116±0.004[6]
0.391±0.038[5]
P[8] · C[4]
10.391±0.002 (R)[11] · 10.50[5] · 10.7[1][4] · 11.1[6][8]

    Orbit

    Disa orbits the Sun in the outer main-belt at a distance of 2.4–3.6 AU once every 5 years and 2 months (1,884 days). Its orbit has an eccentricity of 0.21 and an inclination of 3° with respect to the ecliptic.[1] It was first identified as A908 EA at Heidelberg Observatory in 1908. The body's observation arc begins in 1929, when it was identified as 1929 GE at the discovering observatory, 6 years prior to its official discovery observation.[12]

    Physical characteristics

    Rotation period

    A rotational lightcurve of Disa was obtained by American astronomer Brian D. Warner at his Palmer Divide Observatory in March 2006, and by French amateur astronomer Pierre Antonini in February 2011, respectively. Analysis of both lightcurves gave a well-defined rotation period of 7.08 hours with a brightness variation of 0.26 and 0.27 magnitude (U=3/3).[9][10][lower-alpha 1]

    In September 2013, photometric observations in the R-band at the Palomar Transient Factory gave a concurring lightcurve of 7.082 hours and an amplitude of 0.24 magnitude (U=2).[11]

    Diameter, albedo and spectral type

    According to the surveys carried out by the Japanese Akari satellite, and the 2014-results by NASA's Wide-field Infrared Survey Explorer with its subsequent NEOWISE mission, Disa measures 24.00 and 25.65 kilometers in diameter, and its surface has an albedo of 0.116 and 0.097, respectively.[6]

    The Collaborative Asteroid Lightcurve Link assumes a standard albedo for carbonaceous C-type asteroids of 0.057 and calculates a diameter of 40.33 kilometers with an absolute magnitude of 10.7.[4] Preliminary results by NEOWISE also characterized the body as a dark and reddish P-type asteroid.[8]

    Naming

    This minor planet was named after Disa, also known as "African weed-orchid", a large genus of more than a hundred tropical orchids, common in southern Africa.[3] In 1955, this naming citation was also published by Paul Herget in The Names of the Minor Planets (H 120).[3]

    Notes
    1. Lightcurve plot of 1319 Disa, Palmer Divide Observatory, Brian D. Warner (2006)

    References
    1. "JPL Small-Body Database Browser: 1319 Disa (1934 FO)" (2017-06-05 last obs.). Jet Propulsion Laboratory. Retrieved 25 July 2017.
    2. "disa". Oxford English Dictionary (Online ed.). Oxford University Press. (Subscription or participating institution membership required.)
    3. Schmadel, Lutz D. (2007). "(1319) Disa". Dictionary of Minor Planet Names – (1319) Disa. Springer Berlin Heidelberg. p. 108. doi:10.1007/978-3-540-29925-7_1320. ISBN 978-3-540-00238-3.
    4. "LCDB Data for (1319) Disa". Asteroid Lightcurve Database (LCDB). Retrieved 16 January 2017.
    5. 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 16 January 2017.
    6. 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. (online, AcuA catalog p. 153)
    7. 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 16 January 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. Warner, Brian D. (December 2006). "Asteroid lightcurve analysis at the Palmer Divide Observatory - February - March 2006". The Minor Planet Bulletin. 33 (4): 82–84. Bibcode:2006MPBu...33...82W. ISSN 1052-8091. Retrieved 16 January 2017.
    10. Behrend, Raoul. "Asteroids and comets rotation curves – (1319) Disa". Geneva Observatory. Retrieved 16 January 2017.
    11. 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 16 January 2017.
    12. "1319 Disa (1934 FO)". Minor Planet Center. Retrieved 16 January 2017.

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