968 Petunia

968 Petunia (prov. designation: A921 WJ or 1921 KW), is a stony asteroid of the Itha family, approximately 28 kilometers (17 miles) in diameter, located in the outer region of the asteroid belt. It was discovered on 24 November 1921, by astronomer Karl Reinmuth at the Heidelberg Observatory in southern Germany.[1] The bright S-type asteroid has a long rotation period of 61.3 hours. It was named after the genus of flowering plants, Petunia.[3]

968 Petunia
Modelled shape of Petunia from its lightcurve
Discovery [1]
Discovered byK. Reinmuth
Discovery siteHeidelberg Obs.
Discovery date24 November 1921
Designations
(968) Petunia
Pronunciation/pɪˈtjuːniə/[2]
Named after
Petunia [3]
(genus of flowers)
A921 WJ · 1935 QK1
1948 KC · 1921 KW
main-belt [1][4] · (outer)
Itha [5]
Orbital characteristics [4]
Epoch 31 May 2020 (JD 2459000.5)
Uncertainty parameter 0
Observation arc98.19 yr (35,865 d)
Aphelion3.2572 AU
Perihelion2.4741 AU
2.8657 AU
Eccentricity0.1366
4.85 yr (1,772 d)
15.803°
0° 12m 11.52s / day
Inclination11.598°
208.84°
297.54°
Physical characteristics
Mean diameter
  • 24.422±0.232 km[6]
  • 27.77±2.9 km[7]
  • 29.51±0.49 km[8]
61.280±0.005 h[9][10]
(355.0°, −78.0°) (λ1/β1)[5]
  • 0.233±0.021[6]
  • 0.1803±0.045[7]
  • 0.204±0.008[8]
10.2[1][4]

    Orbit and classification

    When applying the synthetic hierarchical clustering method (HCM) by Nesvorný, Petunia is a member of the Itha family (633),[5] a small family of stony asteroids in the outer main belt, named after 918 Itha.[5][13] However, it is a background asteroid according to another HCM-analysis by Milani and Knežević (AstDys).[14] Petunia orbits the Sun at a distance of 2.5–3.3 AU once every 4 years and 10 months (1,772 days; semi-major axis of 2.87 AU). Its orbit has an eccentricity of 0.14 and an inclination of 12° with respect to the ecliptic.[4] The asteroid was first observed at Heidelberg Observatory on 25 October 1921, where the body's observation arc begins with its official discovery observation one month later on 24 November 1921.[1]

    Naming

    This minor planet was named after a genus of tropical American herbs, Petunia. This genus of flowering plants belongs to the family of Solanaceae (nightshades) and shows funnel-shaped corollas. The naming was mentioned in The Names of the Minor Planets by Paul Herget in 1955 (H 93).[3] Only a minority of minor planets are after animals and plants.

    Physical characteristics

    Petunia is a common stony S-type asteroid in the Tholen classification,[4] in the SDSS-based taxonomy,[11] as well as in the Tholen-like taxonomy of the Small Solar System Objects Spectroscopic Survey (S3OS2), while in the SMASS-like taxonomic variant of the S3OS2 survey, it is an Sl subtype, which transitions from the S-type to the L-type asteroids.[5][12]

    Rotation period and pole

    In December 2009, a rotational lightcurve of Petunia was obtained from photometric observations by Robert Stephens at Santana Observatory (646) and Goat Mountain Astronomical Research Station (G79) in California. Lightcurve analysis gave a long rotation period of 61.280±0.005 hours with a brightness variation of 0.38±0.03 magnitude (U=3).[10]

    Astronomers at the Palomar Transient Factory in California measured a period of 61.207±0.1286 hours and an amplitude of 0.30 magnitude in August 2013 (U=2),[15] while observations by Italian amateur astronomers Roberto Crippa and Federico Manzini at the Sozzago Astronomical Station (A12) in April 2006 were of poor quality (U=1).[16]

    A modeled lightcurve using photometric data from the Lowell Photometric Database was published in 2016. It gave a concurring sidereal period of 61.160±0.001 hours and a spin axis at (355.0°, −78.0°) in ecliptic coordinates (λ, β).[17]

    Diameter and albedo

    According to the surveys carried out by the NEOWISE mission of NASA's Wide-field Infrared Survey Explorer (WISE), the Infrared Astronomical Satellite IRAS, and the Japanese Akari satellite, Petunia measures 24.422±0.232, 27.77±2.9 and 29.51±0.49 kilometers in diameter, and its surface has an albedo of 0.233±0.021, 0.1803±0.045 and 0.204±0.008, respectively.[6][7][8] An additional measurement published by the WISE team gives an alternative mean-diameter of 28.983±0.263 km.[9] The Collaborative Asteroid Lightcurve Link adopts the WISE results revised by Pravec, that is an albedo of 0.1654 and a diameter of 29.12 km based on an absolute magnitude of 10.25.[9] An asteroid occultation on 30 September 2014, gave a best-fit ellipse dimension of (29.0 km × 29.0 km).[5] These timed observations are taken when the asteroid passes in front of a distant star. However the quality of the measurements are poorly rated.[5]

    References
    1. "968 Petunia (A921 WJ)". Minor Planet Center. Retrieved 12 February 2020.
    2. "petunia". Oxford English Dictionary (Online ed.). Oxford University Press. (Subscription or participating institution membership required.)
    3. Schmadel, Lutz D. (2007). "(968) Petunia". Dictionary of Minor Planet Names. Springer Berlin Heidelberg. p. 85. doi:10.1007/978-3-540-29925-7_969. ISBN 978-3-540-00238-3.
    4. "JPL Small-Body Database Browser: 968 Petunia (A921 WJ)" (2020-01-04 last obs.). Jet Propulsion Laboratory. Retrieved 12 February 2020.
    5. "Asteroid 968 Petunia – Nesvorny HCM Asteroid Families V3.0". Small Bodies Data Ferret. Retrieved 12 February 2020.
    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.
    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 12 February 2020.
    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. (online, AcuA catalog p. 153)
    9. "LCDB Data for (968) Petunia". Asteroid Lightcurve Database (LCDB). Retrieved 12 February 2020.
    10. Stephens, Robert D. (July 2010). "Lightcurve Analysis of 581 Tauntonia, 776 Berbericia, and 968 Petunia" (PDF). The Minor Planet Bulletin. 37 (3): 122–123. Bibcode:2010MPBu...37..122S. Archived from the original (PDF) on 13 February 2020. Retrieved 12 February 2020.
    11. Carvano, J. M.; Hasselmann, P. H.; Lazzaro, D.; Mothé-Diniz, T. (February 2010). "SDSS-based taxonomic classification and orbital distribution of main belt asteroids". Astronomy and Astrophysics. 510: 12. Bibcode:2010A&A...510A..43C. doi:10.1051/0004-6361/200913322. Retrieved 30 October 2019. (PDS data set)
    12. Lazzaro, D.; Angeli, C. A.; Carvano, J. M.; Mothé-Diniz, T.; Duffard, R.; Florczak, M. (November 2004). "S3OS2: the visible spectroscopic survey of 820 asteroids" (PDF). Icarus. 172 (1): 179–220. Bibcode:2004Icar..172..179L. doi:10.1016/j.icarus.2004.06.006. Retrieved 9 June 2018.
    13. Nesvorný, D.; Broz, M.; Carruba, V. (December 2014). "Identification and Dynamical Properties of Asteroid Families". Asteroids IV: 297–321. arXiv:1502.01628. Bibcode:2015aste.book..297N. doi:10.2458/azu_uapress_9780816532131-ch016.
    14. "Asteroid 968 Petunia – Proper Elements". AstDyS-2, Asteroids – Dynamic Site. Retrieved 12 February 2020.
    15. 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.
    16. Behrend, Raoul. "Asteroids and comets rotation curves – (968) Petunia". Geneva Observatory. Retrieved 12 February 2020.
    17. 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.
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