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تسجيل مستخدم جديدOrigin of Interstellar Object A/2017 U1 in a Nearby Young Stellar Association?
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We suggest that the kinematics and properties of interstellar object A/2017 U1 point towards its formation in a protoplanetary disk in the ~45 Myr-old Carina or Columba young stellar associations, and subsequent ejection with a low peculiar velocity (1-2 km/sec) during or soon after planet formation inside the ice line. This scenario predicts that the Solar System will encounter more such objects with radiants similar to that of A/2017 U1.
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We study the origin of the interstellar object 1I/2017 U1 Oumuamua by juxtaposing estimates based on the observations with simulations. We speculate that objects like Oumuamua are formed in the debris disc as left over from the star and planet format
ion process, and subsequently liberated. The liberation process is mediated either by interaction with other stars in the parental star-cluster, by resonant interactions within the planetesimal disc or by the relatively sudden mass loss when the host star becomes a compact object. Integrating backward in time in the Galactic potential together with stars from the Gaia-TGAS catalogue we find that about 1.3Myr ago Oumuamua passed the nearby star HIP 17288 within a mean distance of $1.3$pc. By comparing nearby observed L-dwarfs with simulations of the Galaxy we conclude that the kinematics of Oumuamua is consistent with relatively young objects of $1.1$--$1.7$Gyr. We just met Oumuamua by chance, and with a derived mean Galactic density of $sim 3times 10^{5}$ similarly sized objects within 100,au from the Sun or $sim 10^{14}$ per cubic parsec we expect about 2 to 12 such visitors per year within 1au from the Sun.
The initial Galactic velocity vector for the recently discovered hyperbolic asteroid 1I/Oumuamua (A/2017 U1) is calculated for before its encounter with our solar system. The latest orbit (JPL-13) shows that Oumuamua has eccentricity > 1 at 944sigma,
significance (1.19936 +- 0.00021), i.e. clearly unbound. Assuming no non-gravitational forces, the objects inbound Galactic velocity was U, V, W = -11.457, -22.395, -7.746 (+-0.009, +-0.009, +-0.011) km/s (U towards Galactic center), with total heliocentric speed 26.32 +- 0.01 km/s. When the velocity is compared to the local stars, Oumuamua can be ruled out as co-moving with any of the dozen nearest systems, i.e. it does not appear to be associated with any local exo-Oort clouds (most notably that of the Alpha Centauri triple system). Oumuamuas velocity is within 5 km/s of the median Galactic velocity of the stars in the solar neighborhood (<25 pc), and within 2 km/s of the mean velocity of the local M dwarfs. Its velocity appears to be statistically too typical for a body whose velocity was drawn from the Galactic velocity distribution of the local stars (i.e. less than 1 in 500 field stars in the solar neighborhood would have a velocity so close to the median UVW velocity). In the Local Standard of Rest frame (circular Galactic motion), Oumuamua is remarkable for showing both negligible radial (U) and vertical (W) motion, while having a slightly sub-Keplerian circular velocity (V; by ~11 km/s). These calculations strengthen the interpretation that A/2017 U1 has a distant extrasolar origin, but not among the very nearest stars. Any formation mechanism for this interstellar asteroid should account for the coincidence of Oumuamuas velocity being so close to the LSR.
The recently discovered minor body 1I/2017 U1 (`Oumuamua) is the first known object in our Solar System that is not bound by the Suns gravity. Its hyperbolic orbit (eccentricity greater than unity) strongly suggests that it originated outside our Sol
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We present observations of the interstellar interloper 1I/2017 U1 (Oumuamua) taken during its 2017 October flyby of Earth. The optical colors B-V = 0.70$pm$0.06, V-R = 0.45$pm$0.05, overlap those of the D-type Jovian Trojan asteroids and are incompat
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We have performed a WISE (Wide-Field Infrared Survey Explorer) based study to identify and characterize young stellar objects (YSOs) in 12x12 degree Perseus OB2 association. Spectral energy distribution (SED) slope in range of 3.4-12 micron and a 5si
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