Optical observations of near isotropic comet C/2006 OF2 (Broughton) at two different heliocentric distances

DOI: 
10.1016/j.icarus.2020.114156
Publication date: 
01/02/2021
Main author: 
Kulyk I.
IAA authors: 
Lara, L.
Authors: 
Kulyk, I.;Korsun, P.;Lukyanyk, I.;Ivanova, O.;Afanasiev, V.;Lara, L.
Journal: 
Icarus
Refereed: 
Yes
Publication type: 
Article
Volume: 
355
Pages: 
114156
Number: 
114156
Abstract: 
© 2020 Elsevier Inc. Spectra and images of comet C/2006 OF2 (Broughton) were obtained with the 4.2-m William Herschel Telescope (La Palma, Spain) and with the 6-m Big Telescope Alt-azimuth (SAO RAN, Russia) at two observing epochs on October 15, 2007 and December 05, 2008.The comet was at heliocentric distances of 4.24 au and 2.59 au before and after the perihelion, respectively. The emissions CN 0–0, 0–1 (B2Σ+ − X2Σ+), C3 (A1Πu − X1Σg+) bands and C2 0–0 (A3Πg – X3Πu) of the Swan band system were identified in the post-perihelion cometary spectrum. Using the simple Haser model, the gas production rates of CN, C2 and C3 molecules were estimated at level of 1.35 × 1024 mol/s, 0.45 × 1024 mol/s, and 0.12 × 1024 mol/s, respectively. The gas production rate ratios, log(C2/CN) = −0.48 and log(C3/CN) = −1.05, point out that comet C/2006 OF2 probably belongs to the group of “carbon-chain depleted” comets. The ratios between C2, C3 and CN abundances of comet C/2006 OF2 are similar to those recently measured for interstellar comet 2I/Borisov at comparable heliocentric distances. The normalized reflectivity gradients of 12.7 ± 0.2%/1000 Å and − 2.3 ± 0.2%/1000 Å were calculated from the post perihelion spectrum in the intervals 4450 Å – 5500 Å and 5500–6935 Å, respectively, using the spectral regions free from comet emissions. The continuum slope, measured in the interval 4200 Å – 4800 Å, is even steeper, reaching 32.7 ± 0.2%/1000 Å. The normalized reflectivity gradient measured from a pair of the pre-perihelion V and R-images varies between 8%/1000 Å and 11%/1000 Å in the inner part of the coma, which exceeds the value obtained from the similar spectral interval of the post-perihelion spectrum, indicating that the coma became bluer after the perihelion passage. The morphology of the pre-perihelion images of the comet is governed by faint morphological features hidden in the bright coma. The color of the jets isolated from the pre-perihelion images is redder than the color of the ambient coma. The pre- and post-perihelion V-band Afρ parameters were found to be 1990 ± 90 cm and 2500 ± 100 cm for heliocentric distances of 4.24 au and 2.59 au, respectively.
Database: 
SCOPUS
ADS
URL: 
https://ui.adsabs.harvard.edu/#abs/2021Icar..35514156K/abstract
ADS Bibcode: 
2021Icar..35514156K
Keywords: 
Comets: General | Comets: Individual: C/2006 OF2 (Broughton)