_Helina.png) Modelled shape ofHelina from itslightcurve | |
| Discovery[1] | |
|---|---|
| Discovered by | G. Neujmin |
| Discovery site | Simeiz Obs. |
| Discovery date | 29 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 arc | 110.85 yr (40,489 days) |
| Aphelion | 3.3528AU |
| Perihelion | 2.6705 AU |
| 3.0116 AU | |
| Eccentricity | 0.1133 |
| 5.23yr (1,909 days) | |
| 156.59° | |
| 0° 11m 18.96s / day | |
| Inclination | 11.523° |
| 100.81° | |
| 250.61° | |
| Physical characteristics | |
| 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±0.1526h[9] 44.6768±0.0001 h[10] 44.6770±0.0002 h[a] 44.677±0.001 h[11] 44.9±0.1 h[12] | |
| 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] | |
1075 Helina, provisional designation1926 SC, is a stonyEos asteroid from the outer regions of theasteroid belt, approximately 34 kilometers (21 miles) in diameter. It was discovered on 29 September 1926, by astronomerGrigory Neujmin at theSimeiz Observatory on the Crimean peninsula.[14] The asteroid was named after the discoverer's son, Helij Neujmin.[2]
Helina is a member theEos family (606),[3][4] the largestasteroid family of theouter main belt consisting of nearly 10,000 asteroids.[15]: 23 It orbits the Sun in theouter 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 aneccentricity of 0.11 and aninclination of 12° with respect to theecliptic.[1]
The asteroid was first identified asA906 YG atHeidelberg Observatory in December 1906. The body'sobservation arc begins at Simeiz Observatory in October 1926, nine days after its official discovery observation.[14]
Thisminor planet was named after Helij Grigorevich Neujmin (1910–1982), a son of discovererGrigory Neujmin. The author of theDictionary of Minor Planet Names,Lutz Schmadel learned about the naming circumstances from Crimean astronomers I. I. Neyachenko andN. S. Chernykh(see2325 Chernykh).[2]
In theTholen classification,Helina is a stonyS-type asteroid with an unusual spectra (SU).[1][3]
In March 2013, a rotationallightcurve ofHelina was obtained from photometric observations in the R-band by astronomers at thePalomar Transient Factory in California. Lightcurve analysis gave arotation period of 44.554 hours with a brightness variation of 0.91magnitude (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 aslow 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.
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][a] Modelling in the 2018-study also gave twospin axis of (127.0°, −43.0.0°) and (280.0°, −44.0°) inecliptic coordinates (λ, β).[11]
According to the surveys carried out by the Infrared Astronomical SatelliteIRAS, the JapaneseAkari satellite and theNEOWISE mission of NASA'sWide-field Infrared Survey Explorer,Helina measures between 26.198 and 37.93 kilometers in diameter and its surface has analbedo between 0.11 and 0.129.[5][6][7][8] TheCollaborative 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 anabsolute magnitude of 10.15.[3][7]
