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dc.contributor.authorJewitt, David
dc.contributor.authorLuu, Jane
dc.contributor.authorRajagopal, Jayadev
dc.contributor.authorKotulla, Ralf
dc.contributor.authorRidgway, Susan
dc.contributor.authorLiu, Wilson
dc.contributor.authorAugusteijn, Thomas
dc.date.accessioned2018-09-06T13:20:33Z
dc.date.available2018-09-06T13:20:33Z
dc.date.issued2017-11-30
dc.description.abstractWe 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 ± 0.06, V – R = 0.45 ± 0.05, overlap those of the D-type Jovian Trojan asteroids and are incompatible with the ultrared objects that are abundant in the Kuiper Belt. With a mean absolute magnitude <i>H <sub>V</sub></i> = 22.95 and assuming a geometric albedo <i>p <sub>V</sub></i> = 0.1, we find an average radius of 55 m. No coma is apparent; we deduce a limit to the dust mass production rate of only ~2 × 10<sup>−4</sup> kg s<sup>−1</sup>, ruling out the existence of exposed ice covering more than a few m<sup>2</sup> of the surface. Volatiles in this body, if they exist, must lie beneath an involatile surface mantle ≥0.5 m thick, perhaps a product of prolonged cosmic-ray processing in the interstellar medium. The light curve range is unusually large at ~2.0 ± 0.2 mag. Interpreted as a rotational light curve the body has axis ratio ≥ 6.3<sub>-1.1/+1.3</sub>:1 and semi-axes ~230 m × 35 m. A ≥6:1 axis ratio is extreme relative to most small solar system asteroids and suggests that albedo variations may additionally contribute to the variability. The light curve is consistent with a two-peaked period ~8.26 hr, but the period is non-unique as a result of aliasing in the data. Except for its unusually elongated shape, 1I/2017 U1 is a physically unremarkable, sub-kilometer, slightly red, rotating object from another planetary system. The steady-state population of similar, ~100 m scale interstellar objects inside the orbit of Neptune is ~10<sup>4</sup>, each with a residence time of ~10 years.en_US
dc.descriptionSource at <a href=https://doi.org/10.3847/2041-8213/aa9b2f> https://doi.org/10.3847/2041-8213/aa9b2f</a>. ©2017. The American Astronomical Society.en_US
dc.identifier.citationJewitt, D., Luu, J., Rajagopal, J., Kotulla, R., Ridgway, S., Liu, W. & Augusteijn, T. (2017). Interstellar Interloper 1I/2017 U1: Observations from the NOT and WIYN Telescopes. Astrophysical Journal Letters, 850(L36). https://doi.org/10.3847/2041-8213/aa9b2fen_US
dc.identifier.cristinIDFRIDAID 1564395
dc.identifier.doi10.3847/2041-8213/aa9b2f
dc.identifier.issn2041-8205
dc.identifier.issn2041-8213
dc.identifier.urihttps://hdl.handle.net/10037/13702
dc.language.isoengen_US
dc.publisherAmerican Astronomical Societyen_US
dc.relation.journalAstrophysical Journal Letters
dc.rights.accessRightsopenAccessen_US
dc.subjectVDP::Matematikk og Naturvitenskap: 400::Fysikk: 430::Astrofysikk, astronomi: 438en_US
dc.subjectVDP::Mathematics and natural science: 400::Physics: 430::Astrophysics, astronomy: 438en_US
dc.titleInterstellar Interloper 1I/2017 U1: Observations from the NOT and WIYN Telescopesen_US
dc.typeJournal articleen_US
dc.typeTidsskriftartikkelen_US
dc.typePeer revieweden_US


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