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RISS 인기검색어
- 검색키워드
- 저자 : Jedicke, Robert (검색결과 2 건)
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SEARCH FOR THE RETURN OF ACTIVITY IN ACTIVE ASTEROID 176P/LINEAR
Hsieh, Henry H.,Denneau, Larry,Fitzsimmons, Alan,Hainaut, Olivier R.,Ishiguro, Masateru,Jedicke, Robert,Kaluna, Heather M.,Keane, Jacqueline V.,Kleyna, Jan,Lacerda, Pedro,MacLennan, Eric M.,Meech, Kar American Institute of Physics 2014 The Astronomical journal Vol.147 No.4
<P>We present the results of a search for the reactivation of active asteroid 176P/LINEAR during its 2011 perihelion passage using deep optical observations obtained before, during, and after that perihelion passage. Deep composite images of 176P constructed from data obtained between 2011 June and 2011 December show no visible signs of activity, while photometric measurements of the object during this period also show no significant brightness enhancements similar to that observed for 176P between 2005 November and 2005 December when it was previously observed to be active. An azimuthal search for dust emission likewise reveals no evidence for directed emission (i.e., a tail, as was previously observed for 176P), while a one-dimensional surface brightness profile analysis shows no indication of a spherically symmetric coma at any time in 2011. We conclude that 176P did not in fact exhibit activity in 2011, at least not on the level on which it exhibited activity in 2005, and suggest that this could be due to the devolatization or mantling of the active site responsible for its activity in 2005.</P>
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OBSERVATIONAL AND DYNAMICAL CHARACTERIZATION OF MAIN-BELT COMET P/2010 R2 (La Sagra)
Hsieh, Henry H.,Yang, Bin,Haghighipour, Nader,Novaković,, Bojan,Jedicke, Robert,Wainscoat, Richard J.,Denneau, Larry,Abe, Shinsuke,Chen, Wen-Ping,Fitzsimmons, Alan,Granvik, Mikael,Grav, Tommy,Ip, American Institute of Physics 2012 The Astronomical journal Vol.143 No.5
<P>We present observations of the recently discovered comet-like main-belt object P/2010 R2 (La Sagra) obtained by Pan-STARRS1 and the Faulkes Telescope-North on Haleakala in Hawaii, the University of Hawaii 2.2 m, Gemini-North, and Keck I telescopes on Mauna Kea, the Danish 1.54 m telescope (operated by the MiNDSTEp consortium) at La Silla, and the Isaac Newton Telescope on La Palma. An antisolar dust tail is observed to be present from 2010 August through 2011 February, while a dust trail aligned with the object's orbit plane is also observed from 2010 December through 2011 August. Assuming typical phase darkening behavior, P/La Sagra is seen to increase in brightness by >1 mag between 2010 August and December, suggesting that dust production is ongoing over this period. These results strongly suggest that the observed activity is cometary in nature (i.e., driven by the sublimation of volatile material), and that P/La Sagra is therefore the most recent main-belt comet to be discovered. We find an approximate absolute magnitude for the nucleus of H<SUB>R</SUB> = 17.9 ± 0.2 mag, corresponding to a nucleus radius of ~0.7 km, assuming an albedo of p = 0.05. Comparing the observed scattering surface areas of the dust coma to that of the nucleus when P/La Sagra was active, we find dust-to-nucleus area ratios of A<SUB>d</SUB>/A<SUB>N</SUB> = 30-60, comparable to those computed for fellow main-belt comets 238P/Read and P/2008 R1 (Garradd), and one to two orders of magnitude larger than for two other main-belt comets (133P/Elst-Pizarro and 176P/LINEAR). Using optical spectroscopy to search for CN emission, we do not detect any conclusive evidence of sublimation products (i.e., gas emission), finding an upper limit CN production rate of Q<SUB>CN</SUB> < 6 × 10<SUP>23</SUP> mol s<SUP>–1</SUP>, from which we infer an H<SUB>2</SUB>O production rate of <img SRC='http://ej.iop.org/images/1538-3881/143/5/104/aj423523ieqn1.gif' ALIGN='MIDDLE' ALT='$Q_{\rm H_2O}\,{<}\,10^{26}$'/> mol s<SUP>–1</SUP>. Numerical simulations indicate that P/La Sagra is dynamically stable for >100 Myr, suggesting that it is likely native to its current location and that its composition is likely representative of other objects in the same region of the main belt, though the relatively close proximity of the 13:6 mean-motion resonance with Jupiter and the (3,–2,–1) three-body mean-motion resonance with Jupiter and Saturn mean that dynamical instability on larger timescales cannot be ruled out.</P>
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