 | |
| Discovery[1][2] | |
|---|---|
| Discovered by | R. H. McNaught |
| Discovery site | Siding Spring Obs. |
| Discovery date | 9 November 1991 |
| Designations | |
| 1991 VH | |
| NEO · Apollo · PHA[3] | |
| Orbital characteristics[3] | |
| Epoch 21 January 2022 (JD 2459600.5) | |
| Uncertainty parameter 0 | |
| Observation arc | 29.34 yr (10,717 days) |
| Aphelion | 1.3014AU |
| Perihelion | 0.9732 AU |
| 1.1373 AU | |
| Eccentricity | 0.1443 |
| 1.21 yr (443.02 days) | |
| 7.959° | |
| 0° 48m 45.357s / day | |
| Inclination | 13.912° |
| 139.349° | |
| 206.940° | |
| Knownsatellites | 1 |
| Earth MOID | 0.02467 AU (3,691,000 km; 9.60 LD) |
| Physical characteristics[4] | |
| Dimensions | 1.30 × 1.25 × 1.18 km[5] |
| 1.18±0.18 km (primary)[5] | |
| Mass | (1.58±0.08)×1012 kg (system)[5] 1.4×1012 kg (primary)[a] |
Meandensity | 1.7±0.8 g/cm3[5] |
| 2.6238±0.0001 h[6][4] | |
| 0.17–0.18[5] | |
| Sk (SMASS)[3] V–R=0.38±0.04[7] R–I=0.36±0.04[7] | |
| 17.02±0.07 (H-G)[b] 16.76 (assumed)[c] | |
(35107) 1991 VH (provisional designation1991 VH) is abinarynear-Earth asteroid andpotentially hazardous asteroid of theApollo group. It was discovered on 9 November 1991, by Australian astronomerRobert McNaught atSiding Spring Observatory. This binary system is composed of a roughly-spheroidalprimary body about one kilometre in diameter, and an elongatednatural satellite less than half a kilometre in diameter.[5]
The1991 VH system is unusual for its dynamically excited state; the satellite has atumbling,non-synchronous rotation thatchaotically exchanges energy andangular momentum with itsprecessing,eccentric orbit.[11][6] The cause of this is not known however a likely scenario is that (35107) 1991 VH had a close planetary encounter with Earth within ~50,000 to 80,000 kilometers. Another idea, though very unlikely, is that 1991 VH experienced a significant collision event within the past million years.[12]
This asteroid system was one of the two targets ofNASA'sJanus Mayhem mission,[13][14] until the delay of the rocket launch made both targets inaccessible.[15]
Thisminor planet wasnumbered by theMinor Planet Center on 27 February 2002.[16] It has not yet beennamed.[1]
1991 VH orbits the Sun at a distance of 0.98–1.30 AU once every 1.21 years (443 days). Its orbit has aneccentricity of 0.14 and aninclination of 14° with respect to theecliptic.[3]
The asteroid has an Earthminimum orbital intersection distance of 0.0247 AU (3.70 million km; 2.30 million mi), which translates into approximately 9.6lunar distances (LD). It has made multiple close approaches toEarth, with the closest being 0.0458 AU (6.85 million km; 4.26 million mi) or 17.8 LD on 15 August 2008.[3]
High-resolution radar imaging fromGoldstone andArecibo Observatory in 2008 show that the1991 VH primary is a roughly-spheroidal object with an equatorialridge, bearing resemblance to a spinningtop. This shape is not unique to1991 VH as it been observed in other near-Earth asteroids; most notably3200 Phaethon,66391 Moshup,101955 Bennu, and162173 Ryugu.[5][17] A number of topographical features, including a 100 m (330 ft)-wide concavity, are present along the object's equatorial ridge. A bright linear feature casting a shadow at the object's mid- to high-latitudes was also seen in the 2008 radar images.[5]
Preliminary modeling of the primary's shape in radar images indicates dimensions of 1.30 km × 1.25 km × 1.18 km (0.81 mi × 0.78 mi × 0.73 mi), or a volume-equivalent diameter of 1.18 km (0.73 mi).[5] Thegeometric albedo for the primary is 0.17–0.18, considerably lower than infrared-based estimates of 0.30–0.40.[8][4]
The total mass of the1991 VH system is(1.58±0.08)×1012 kg, based on the orbital motion of the satellite. The mass ratio of the satellite to the primary is0.086±0.018, corresponding to a primary mass of1.4×1012 kg—approximately 12 times as massive as the satellite.[a] Given the primary mass and diameter, its density is estimated to be about1.7±0.8 g/cm3, indicative of arubble pile internal structure.[5][18]
In theSMASS taxonomy,1991 VH is classified as a transitional Sk-type, which is an intermediary between the common stonyS-type and the less frequentK-type asteroids.[3]
Photometric observations in 1997 determined a primaryrotation period of 2.624 hours, with alight curve amplitude of0.08±0.01 magnitudes (U=3).[7] Later photometric observations from 2003–2020 corroborated this result down to a precision of ±0.0001 seconds.[4][19]
 Radar images ofS/2008 (35107) 1 byArecibo Observatory on 12 August 2008 | |
| Discovery[20][21] | |
|---|---|
| Discovered by | P. Pravec M. Wolf L. Šarounová |
| Discovery site | Ondřejov Obs. |
| Discovery date | 27 February 1997 |
| Designations | |
| S/1997 (35107) 1 [spurious designation at JPL][3] | |
| Orbital characteristics[5] | |
| 3.32±0.07 km | |
| Eccentricity | 0.05±0.02[6][9] |
| 32.57±0.3 h (1.357±0.012 d) | |
| Inclination | 148°±9° (wrtecliptic)[3][9] |
| 270°±30°[3][9] | |
| Physical characteristics | |
| Dimensions | a/b =1.33±0.10[22] |
| 0.42±0.08 km[23] (Ds/Dp=0.40±0.02)[9] | |
| Mass | 1.4×1011 kg[d] |
| 11–16 h (chaotic)[6] | |
| 17.2 (Δmag=0.2)[21] | |
S/2008 (35107) 1 is the secondary component andnatural satellite of the1991 VH system.
S/2008 (35107) 1 is among the firstnear-Earth asteroid satellites discovered, alongside those of(385186) 1994 AW1 and3671 Dionysus.[7] It was discovered on 27 February 1997, by astronomersPetr Pravec, Marek Wolf, and Lenka Šarounová atOndřejov Observatory. The satellite was detected through photometric observations of periodic dips in the system's brightness, caused by mutualeclipses andoccultations of the components.[20] The discovery of the satellite was reported in a notice published by theInternational Astronomical Union on 29 March 1997, but was not officially confirmed until it was individually resolved inadaptive optics imaging by theKeck II telescope atMauna Kea Observatory on 9 August 2008. The satellite was given theprovisional designationS/2008 (35107) 1 on 19 September 2008.[21][23]
As with many binary near-Earth asteroids, the1991 VH system is thought to have formed through rotational fissioning of a progenitor body due to spin-up by theYORP effect. The resulting mass shed from the progenitor body coalesced in orbit to form the satellite.[18]
This asteroid system was the target ofNASA'sJanus Mayhem mission, which was planned to launch in 2022 alongside NASA'sPsyche spacecraft, and to arrive in 2026.[13][14]1991 VH became impossible to reach forJanus when the launch of Psyche got delayed in May 2022.[15]
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