اشترك بالحزمة الذهبية واحصل على وصول غير محدود شمرا أكاديميا
تسجيل مستخدم جديدA kinematical age for the interstellar object 1I/Oumuamua
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1I/Oumuamua is the first interstellar object observed passing through the Solar System. Understanding the nature of these objects will provide crucial information about the formation and evolution of planetary systems, and the chemodynamical evolution of the Galaxy as a whole. We obtained the galactic orbital parameters of this object, considering 8 different models for the Galaxy, and compared it to those of stars of different ages from the Geneva-Copenhagen Survey (GCS). Assuming that the galactic orbital evolution of this object is similar to that of stars, we applied a Bayesian analyses and used the distribution of stellar velocities, as a function of age, to obtain a probability density function for the age of Oumuamua. We considered two models for the age-velocity dispersion relation (AVR): the traditional power law, fitted using data from the GCS; and a model that implements a second power law for younger ages, which we fitted using a sample of 153 Open Clusters (OCs). We find that the slope of the AVR is smaller for OCs than it is for field stars. Using these AVRs, we constrained an age range of 0.01-1.87 Gyr for Oumuamua and characterized a most likely age ranging between 0.20-0.45 Gyr, depending on the model used for the AVR. We also estimated the intrinsic uncertainties of the method due to not knowing the exact value of the Solar motion and the particularities of 1I/Oumuamuas ejection.
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1I/`Oumuamua is the first confirmed interstellar body in our Solar System. Here we report on observations of `Oumuamua made with the Spitzer Space Telescope on 2017 November 21--22 (UT). We integrated for 30.2~hours at 4.5 micron (IRAC channel 2). We
did not detect the object and place an upper limit on the flux of 0.3 uJy (3sigma). This implies an effective spherical diameter less than [98, 140, 440] meters and albedo greater than [0.2, 0.1, 0.01] under the assumption of low, middle, or high thermal beaming parameter eta, respectively. With an aspect ratio for `Oumuamua of 6:1, these results correspond to dimensions of [240:40, 341:57, 1080:180] meters, respectively. We place upper limits on the amount of dust, CO, and CO2 coming from this object that are lower than previous results; we are unable to constrain the production of other gas species. Both our size and outgassing limits are important because `Oumuamuas trajectory shows non-gravitational accelerations that are sensitive to size and mass and presumably caused by gas emission. We suggest that `Oumuamua may have experienced low-level post-perihelion volatile emission that produced a fresh, bright, icy mantle. This model is consistent with the expected eta value and implied high albedo value for this solution, but, given our strict limits on CO and CO2, requires another gas species --- probably H2O --- to explain the observed non-gravitational acceleration. Our results extend the mystery of `Oumuamuas origin and evolution.
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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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,
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