_Petunia.png) Modelled shape ofPetunia from itslightcurve | |
| Discovery[1] | |
|---|---|
| Discovered by | K. Reinmuth |
| Discovery site | Heidelberg Obs. |
| Discovery date | 24 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 arc | 98.19yr (35,865 d) |
| Aphelion | 3.2572AU |
| Perihelion | 2.4741 AU |
| 2.8657 AU | |
| Eccentricity | 0.1366 |
| 4.85 yr (1,772 d) | |
| 15.803° | |
| 0° 12m 11.52s / day | |
| Inclination | 11.598° |
| 208.84° | |
| 297.54° | |
| Physical characteristics | |
| 61.280±0.005 h[9][10] | |
| (355.0°, −78.0°) (λ1/β1)[5] | |
| 10.2[1][4] | |
968 Petunia (prov. designation:A921 WJor1921 KW), is a stonyasteroid of theItha family, approximately 28 kilometers (17 miles) in diameter, located in the outer region of theasteroid belt. It was discovered on 24 November 1921, by astronomerKarl Reinmuth at theHeidelberg Observatory in southern Germany.[1] The brightS-type asteroid has a longrotation period of 61.3 hours. It was named after the genus of flowering plants,Petunia.[3]
When applying the synthetichierarchical clustering method (HCM) byNesvorný,Petunia is a member of theItha family (633),[5] a smallfamily of stony asteroids in theouter main belt, named after918 Itha.[5][13] However, it is abackground asteroid according to another HCM-analysis byMilani andKnežević (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 aneccentricity of 0.14 and aninclination of 12° with respect to theecliptic.[4] The asteroid was first observed atHeidelberg Observatory on 25 October 1921, where the body'sobservation arc begins with its official discovery observation one month later on 24 November 1921.[1]
Thisminor planet was named after a genus of tropical American herbs,Petunia. This genus of flowering plants belongs to the family ofSolanaceae (nightshades) and shows funnel-shaped corollas. Thenaming was mentioned inThe Names of the Minor Planets byPaul Herget in 1955 (H 93).[3] Only a minority of minor planets are after animals and plants.
Petunia is a common stonyS-type asteroid in theTholen classification,[4] in theSDSS-based taxonomy,[11] as well as in the Tholen-like taxonomy of theSmall 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 theL-type asteroids.[5][12]
In December 2009, a rotationallightcurve ofPetunia was obtained fromphotometric observations byRobert Stephens at Santana Observatory (646) and Goat Mountain Astronomical Research Station (G79) in California. Lightcurve analysis gave a longrotation period of61.280±0.005 hours with a brightness variation of0.38±0.03magnitude (U=3).[10]
Astronomers at thePalomar Transient Factory in California measured a period of61.207±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 of61.160±0.001 hours and aspin axis at (355.0°, −78.0°) inecliptic coordinates (λ, β).[17]
According to the surveys carried out by theNEOWISE mission of NASA'sWide-field Infrared Survey Explorer (WISE), the Infrared Astronomical SatelliteIRAS, and the JapaneseAkari satellite,Petunia measures24.422±0.232,27.77±2.9 and29.51±0.49 kilometers in diameter, and its surface has analbedo of0.233±0.021,0.1803±0.045 and0.204±0.008, respectively.[6][7][8] An additional measurement published by the WISE team gives an alternative mean-diameter of28.983±0.263 km.[9] TheCollaborative 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 anabsolute magnitude of 10.25.[9] Anasteroid 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]
