1693 Hertzsprung

1693 Hertzsprung (prov. designation: 1935 LA) is a dark and elongated background asteroid from the middle region of the asteroid belt, approximately 39 kilometers in diameter. It was discovered on 5 May 1935, by Dutch astronomer Hendrik van Gent at the Leiden Southern Station, annex to the Johannesburg Observatory in South Africa.[1]

1693 Hertzsprung
Shape model of Hertzsprung from its lightcurve
Discovery [1]
Discovered byH. van Gent
Discovery siteJohannesburg Obs.
(Leiden Southern Station)
Discovery date5 May 1935
Designations
(1693) Hertzsprung
Named after
Ejnar Hertzsprung
(chemist, astronomer)[2]
1935 LA · 1930 HG
1944 HA · 1950 VM
main-belt · (central)
Orbital characteristics [3]
Epoch 4 September 2017 (JD 2458000.5)
Uncertainty parameter 0
Observation arc81.90 yr (29,914 days)
Aphelion3.5603 AU
Perihelion2.0306 AU
2.7955 AU
Eccentricity0.2736
4.67 yr (1,707 days)
164.16°
0° 12m 39.24s / day
Inclination11.942°
69.989°
234.93°
Physical characteristics
Dimensions30.95±8.64[4]
35.27±0.47 km[5]
37.772±0.320[6]
38.67±1.5 km (IRAS:5)[7]
39±4 km[8]
40.396±0.972 km[9]
41.97±3.65[10]
8.825 h[11]
0.03±0.01[10]
0.0330±0.0034[9]
0.0484±0.004 (IRAS:5)[7]
0.05±0.01[8]
0.05±0.05[4]
0.051±0.011[6]
0.059±0.002[5]
Tholen = CBU[3]
P[9] · C[12]
B–V = 0.762[3]
U–B = 0.358[3]
10.97[3][5][7][8][9][12] · 11.39±0.82[13]

    Classification and orbit

    Hertzsprung orbits the Sun in the central main-belt at a distance of 2.0–3.6 AU once every 4 years and 8 months (1,707 days). Its orbit has an eccentricity of 0.27 and an inclination of 12° with respect to the ecliptic.[3] The asteroid was already observed as 1930 HG at Crimea-Simeis in 1930. This observation, however, remained unused and the body's observation arc begins with its official discovery observation at Johannesburg in 1935.[1]

    Naming

    This minor planet was named in memory of Danish chemist and astronomer Ejnar Hertzsprung (1873–1967), best known for the famous Hertzsprung–Russell diagram, a spectral classification system for stars he developed jointly with Russel, after whom the asteroid 1762 Russell was named. From 1934 to 1945, Hertzsprung was the head of the Leiden Observatory in the Netherlands.[2]

    As a prominent expert in photometry, he initiated a survey of variable stars in the Southern Milky Way at the Leiden Southern Station. A number of asteroids and comets were also discovered during the course of this survey. The asteroid's name was suggested by the staff at Leiden Observatory.[2] The official naming citation was published by the Minor Planet Center on 15 December 1967 (M.P.C. 2822).[14]

    Physical characteristics

    Diameter and albedo

    According to the space-based surveys carried out by the Infrared Astronomical Satellite IRAS, the Japanese Akari satellite, and NASA's Wide-field Infrared Survey Explorer with its subsequent NEOWISE mission, Hertzsprung measures between 30.95 and 41.97 kilometers in diameter and its surface has an albedo between 0.03 and 0.059.[4][5][6][7][8][9][10]

    The Collaborative Asteroid Lightcurve Link agrees with the results obtained by IRAS, that is an albedo of 0.048 and a diameter of 38.7 kilometers with an absolute magnitude of 10.97.[12] While the dark C-type asteroid is classified as a rare CBU-subtype on the Tholen taxonomic scheme, the NEOWISE mission groups the body to the rare and reddish P-type asteroids.[9]

    Rotation and shape

    In August 1987, a rotational lightcurve of Hertzsprung was obtained from photometric observations made with the ESO 1-metre telescope at La Silla Observatory in Chile. The lightcurve gave it a well-defined rotation period of 8.825 hours with a brightness amplitude of 0.45 magnitude (U=3).[11] Observations by the NEOWISE mission found higher amplitudes of 0.70 and 1.05, which indicates that the body has a non-spheroidal or elongated shape.[4][10]

    References
    1. "1693 Hertzsprung (1935 LA)". Minor Planet Center. Retrieved 16 May 2016.
    2. Schmadel, Lutz D. (2007). "(1693) Hertzsprung". Dictionary of Minor Planet Names – (1693) Hertzsprung. Springer Berlin Heidelberg. p. 135. doi:10.1007/978-3-540-29925-7_1694. ISBN 978-3-540-00238-3.
    3. "JPL Small-Body Database Browser: 1693 Hertzsprung (1935 LA)" (2017-03-29 last obs.). Jet Propulsion Laboratory. Retrieved 1 July 2017.
    4. Nugent, C. R.; Mainzer, A.; Masiero, J.; Bauer, J.; Cutri, R. M.; Grav, T.; et al. (December 2015). "NEOWISE Reactivation Mission Year One: Preliminary Asteroid Diameters and Albedos". The Astrophysical Journal. 814 (2): 13. arXiv:1509.02522. Bibcode:2015ApJ...814..117N. doi:10.1088/0004-637X/814/2/117. Retrieved 20 April 2017.
    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.; 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 8 December 2016.
    7. Tedesco, E. F.; Noah, P. V.; Noah, M.; Price, S. D. (October 2004). "IRAS Minor Planet Survey V6.0". NASA Planetary Data System – IRAS-A-FPA-3-RDR-IMPS-V6.0. Bibcode:2004PDSS...12.....T. Retrieved 17 October 2019.
    8. Alí-Lagoa, V.; de León, J.; Licandro, J.; Delbó, M.; Campins, H.; Pinilla-Alonso, N.; Kelley, M. S. (June 2013). "Physical properties of B-type asteroids from WISE data". Astronomy & Astrophysics. 554: 16. arXiv:1303.5487. Bibcode:2013A&A...554A..71A. doi:10.1051/0004-6361/201220680. Retrieved 10 November 2015.
    9. 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. Retrieved 16 May 2016.
    10. Nugent, C. R.; Mainzer, A.; Bauer, J.; Cutri, R. M.; Kramer, E. A.; Grav, T.; et al. (September 2016). "NEOWISE Reactivation Mission Year Two: Asteroid Diameters and Albedos". The Astronomical Journal. 152 (3): 12. arXiv:1606.08923. Bibcode:2016AJ....152...63N. doi:10.3847/0004-6256/152/3/63. Retrieved 20 April 2017.
    11. Barucci, M. A.; di Martino, M.; Fulchignoni, M. (May 1992). "Rotational properties of small asteroids - Photoelectric observations". Astronomical Journal. 103: 1679–1686. Bibcode:1992AJ....103.1679B. doi:10.1086/116185. ISSN 0004-6256. Retrieved 10 November 2015.
    12. "LCDB Data for (1693) Hertzsprung". Asteroid Lightcurve Database (LCDB). Retrieved 16 May 2016.
    13. 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 16 May 2016.
    14. Schmadel, Lutz D. (2009). "Appendix – Publication Dates of the MPCs". Dictionary of Minor Planet Names – Addendum to Fifth Edition (2006–2008). Springer Berlin Heidelberg. p. 221. doi:10.1007/978-3-642-01965-4. ISBN 978-3-642-01964-7.

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