Frozen To Death? Detection Of Comet Hale-Bopp At 30.7 AU (Research Note)

dc.contributor.utaustinauthorSzabo, G. M.en_US
dc.creatorSzabo, G. M.en_US
dc.creatorSarneczky, K.en_US
dc.creatorKiss, L. L.en_US
dc.description.abstractContext. Comet Hale-Bopp 9C/1995 O1) has been the most interesting comet ever encountered by modern astronomy, which continued to display significant activity at a solar distance of 25.7 AU. It is unclear when and how this activity will finally cease. Aims. We present new observations with the ESO 2.2 m telescope at La Silla to monitor the activity of Hale-Bopp at 30.7 AU solar distance. Methods. On 2010-12-04, 26 CCD images were taken with 180 s exposure times for photometry and morphology. Results. The comet was detected in R and had a total brightness of 23(m).3 +/- 0(m).2, which corresponds to an absolute brightness of R(1, 1, 0) = 8(m).3. The profile of the coma was star-like at a seeing of 1 ''.9, without any evidence of a coma or tail extending farther than 2 ''.5 (= 55 000 km in projection) and exceeding 26.5 mag/arcs(2) surface brightness. The measured total brightness corresponds to a relative total reflecting surface, a(R)C, of 485 km(2), nine times less than three years before. The calculated a(R)C value would imply a nucleus with 60-65 km radius assuming 4% albedo. This size estimate contradicts significantly the previous results scattering around 35 km. Conclusions. We propose that the comet may still be in a low level of activity, despite the lack of a prominent coma. Alternatively, if the nucleus is already dormant, the albedo should be as high as 13%, assuming a radius of 35 km. With this observation, Hale-Bopp has become the most distant comet ever observed, far beyond the orbit of Neptune.en_US
dc.description.sponsorshipHungarian OTKA K76816, K83790, MB08C 81013en_US
dc.description.sponsorshipHungarian Academy of Sciencesen_US
dc.description.sponsorshipEotvos Fellowship of the Hungarian Stateen_US
dc.identifier.citationSzabó, Gy M., K. Sárneczky, and L. L. Kiss. >Frozen to death? Detection of comet Hale-Bopp at 30.7 AU.> Astronomy & Astrophysics, Vol. 531 (Jul., 2011): A11.en_US
dc.relation.ispartofserialAstronomy & Astrophysicsen_US
dc.rightsAdministrative deposit of works to Texas ScholarWorks: This works author(s) is or was a University faculty member, student or staff member; this article is already available through open access or the publisher allows a PDF version of the article to be freely posted online. The library makes the deposit as a matter of fair use (for scholarly, educational, and research purposes), and to preserve the work and further secure public access to the works of the University.en_US
dc.subjectcomets: individual: hale-boppen_US
dc.subjecttechniques: photometricen_US
dc.subjectdistant cometsen_US
dc.subjectccd photometryen_US
dc.subjectperiod cometsen_US
dc.subjectastronomy & astrophysicsen_US
dc.titleFrozen To Death? Detection Of Comet Hale-Bopp At 30.7 AU (Research Note)en_US

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