1075 Helina

1075 Helina, provisional designation 1926 SC, is a stony Eos asteroid from the outer regions of the asteroid belt, approximately 34 kilometers (21 miles) in diameter. It was discovered on 29 September 1926, by astronomer Grigory Neujmin at the Simeiz Observatory on the Crimean peninsula.[14] The asteroid was named after the discoverer's son, Helij Neujmin.[2]

1075 Helina
Modelled shape of Helina from its lightcurve
Discovery [1]
Discovered byG. Neujmin
Discovery siteSimeiz Obs.
Discovery date29 September 1926
Designations
(1075) Helina
Named after
Helij Neujmin [2]
(discoverer's son)
1926 SC · 1930 KV
1965 CB · A906 YG
A916 WH
main-belt · (outer)
Eos [3][4]
Orbital characteristics [1]
Epoch 4 September 2017 (JD 2458000.5)
Uncertainty parameter 0
Observation arc110.85 yr (40,489 days)
Aphelion3.3528 AU
Perihelion2.6705 AU
3.0116 AU
Eccentricity0.1133
5.23 yr (1,909 days)
156.59°
0° 11m 18.96s / day
Inclination11.523°
100.81°
250.61°
Physical characteristics
Mean diameter
26.198±0.414 km[5]
30.39±7.76 km[6]
34.48±0.58 km[5]
35.52 km[3][7]
37.93±0.85 km[8]
44.554±0.1526 h[9]
44.6768±0.0001 h[10]
44.6770±0.0002 h[lower-alpha 1]
44.677±0.001 h[11]
44.9±0.1 h[12]
  • (127.0°, −43.0.0°) (λ1/β1)[4]
  • (280.0°, −44.0°) (λ2/β2)[4]
0.11±0.07[6]
0.111±0.005[8]
0.1220[3][7]
0.129±0.009[5]
Tholen = SU [1][3]
B–V = 0.765[1]
U–B = 0.370[1]
10.10±0.43[13] · 10.15[1][3][5][7][8] · 10.31[6] · 10.371±0.003 (R)[9]

    Orbit and classification

    Helina is a member the Eos family (606),[3][4] the largest asteroid family of the outer main belt consisting of nearly 10,000 asteroids.[15]:23 It orbits the Sun in the outer asteroid belt at a distance of 2.7–3.4 AU once every 5 years and 3 months (1,909 days; semi-major axis of 3.01 AU). Its orbit has an eccentricity of 0.11 and an inclination of 12° with respect to the ecliptic.[1]

    The asteroid was first identified as A906 YG at Heidelberg Observatory in December 1906. The body's observation arc begins at Simeiz Observatory in October 1926, nine days after its official discovery observation.[14]

    Naming

    This minor planet was named after Helij Grigorevich Neujmin (1910–1982), a son of discoverer Grigory Neujmin. The author of the Dictionary of Minor Planet Names, Lutz Schmadel learned about the naming circumstances from Crimean astronomers I. I. Neyachenko and N. S. Chernykh (see 2325 Chernykh).[2]

    Physical characteristics

    In the Tholen classification, Helina is a stony S-type asteroid with an unusual spectra (SU).[1][3]

    Rotation period

    In March 2013, a rotational lightcurve of Helina was obtained from photometric observations in the R-band by astronomers at the Palomar Transient Factory in California. Lightcurve analysis gave a rotation period of 44.554 hours with a brightness variation of 0.91 magnitude (U=2).[9] In April 2013, European amateur astronomers Matthieu Bachschmidt, Paul Krafft, Olivier Gerteis, Hubert Gully and Luc Arnold measured a period of 44.9 hours with an amplitude of 0.64 magnitude (U=3-).[12]

    While not being a slow rotator, Helina has a longer-than average period. Its high brightness amplitude is also indicative for an elongated or irregular shape, rather than a spherical one.

    Poles

    The asteroid's lightcurve has also been modeled several times. It gave a concurring period of 44.6768 and 44.677 hours, respectively.[10][11][lower-alpha 1] Modelling in the 2018-study also gave two spin axis of (127.0°, −43.0.0°) and (280.0°, −44.0°) in ecliptic coordinates (λ, β).[11]

    Diameter and albedo

    According to the surveys carried out by the Infrared Astronomical Satellite IRAS, the Japanese Akari satellite and the NEOWISE mission of NASA's Wide-field Infrared Survey Explorer, Helina measures between 26.198 and 37.93 kilometers in diameter and its surface has an albedo between 0.11 and 0.129.[5][6][7][8] The Collaborative Asteroid Lightcurve Link adopts the results obtained by IRAS, that is an albedo of 0.1220 and a diameter of 35.52 kilometers based on an absolute magnitude of 10.15.[3][7]

    Notes
    1. Hanus (2016d) publication not indexed in ADS. Summary figures for (1075) Helina at LCDB

    References
    1. "JPL Small-Body Database Browser: 1075 Helina (1926 SC)" (2017-10-30 last obs.). Jet Propulsion Laboratory. Retrieved 6 December 2017.
    2. Schmadel, Lutz D. (2007). "(1075) Helina". Dictionary of Minor Planet Names – (1075) Helina. Springer Berlin Heidelberg. p. 92. doi:10.1007/978-3-540-29925-7_1076. ISBN 978-3-540-00238-3.
    3. "LCDB Data for (1075) Helina". Asteroid Lightcurve Database (LCDB). Retrieved 6 December 2017.
    4. "Asteroid 1075 Helina – Nesvorny HCM Asteroid Families V3.0". Small Bodies Data Ferret. Retrieved 26 October 2019.
    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 6 December 2017.
    6. 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 6 December 2017.
    7. Tedesco, E. F.; Noah, P. V.; Noah, M.; Price, S. D. (October 2004). "IRAS Minor Planet Survey V6.0". NASA Planetary Data System. 12: IRAS-A-FPA-3-RDR-IMPS-V6.0. Bibcode:2004PDSS...12.....T. Retrieved 22 October 2019.
    8. 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)
    9. 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 6 December 2017.
    10. Durech, J.; Hanus, J.; Oszkiewicz, D.; Vanco, R. (March 2016). "Asteroid models from the Lowell photometric database". Astronomy and Astrophysics. 587: 6. arXiv:1601.02909. Bibcode:2016A&A...587A..48D. doi:10.1051/0004-6361/201527573. Retrieved 6 December 2017.
    11. Hanus, J.; Delbo', M.; Alí-Lagoa, V.; Bolin, B.; Jedicke, R.; Durech, J.; et al. (January 2018). "Spin states of asteroids in the Eos collisional family". Icarus. 299: 84–96. arXiv:1707.05507. Bibcode:2018Icar..299...84H. doi:10.1016/j.icarus.2017.07.007.
    12. Behrend, Raoul. "Asteroids and comets rotation curves – (1075) Helina". Geneva Observatory. Retrieved 6 December 2017.
    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 6 December 2017.
    14. "1075 Helina (1926 SC)". Minor Planet Center. Retrieved 6 December 2017.
    15. Nesvorný, D.; Broz, M.; Carruba, V. (December 2014). Identification and Dynamical Properties of Asteroid Families. Asteroids IV. pp. 297–321. arXiv:1502.01628. Bibcode:2015aste.book..297N. doi:10.2458/azu_uapress_9780816532131-ch016. ISBN 9780816532131.
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