High resolution observation of 17P/ Holmes during the outburst event in 2007

Capria, M. T.; Cremonese, G.; Sanctis, M. C. De

doi:10.1051/0004-6361/200913889

Cited by 14 publications

(10 citation statements)

References 28 publications

(28 reference statements)

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“…Considering the theoretical production rates of Raghuram & Bhardwaj (2013; see Table 1 of Decock et al (2015), the 1 S/ 1 D ratio corresponding to the G/R ratio), these results confirm that H 2 O is the main parent molecule that photodissociates to produce oxygen atoms when the comet is observed at a heliocentric distance of r ∼ 1 au. This agrees with previous analyses reported for other comets (Cochran 1984(Cochran , 2008Capria et al 2010;Decock et al 2013, and references therein).…”

Section: [Oi] Linessupporting

confidence: 94%

High-resolution spectra of comet C/2013 R1 (Lovejoy)

Rousselot

Decock

Корсун

et al. 2015

A&A

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Context. High-resolution spectra of comets permit deriving the physical properties of the coma. In the optical range, relative production rates can be computed, and information about isotopic ratios and the origin of oxygen atoms can be obtained. Aims. The main objective of the work presented here was to obtain information about the chemical composition of comet C/2013 R1 (Lovejoy), a bright and long-period comet that passed perihelion (0.81 au) on 22 December 2013. Methods. We used the HARPS-North echelle spectrograph at the 3.5 m telescope TNG to obtain high-resolution spectra of comet C/2013 R1 (Lovejoy) in the optical range immediately after its perihelion passage during four consecutive nights in the period December 23 to 26, 2013.Results. Our results demonstrate the ability of HARPS-North to efficiently obtain cometary spectra. Very faint emission lines, such as those of 15 NH 2 , have been detected, leading to a rough estimate of the 14 N/ 15 N ratio in NH 2 . The 12 C/ 13 C ratio was measured in the C 2 lines and is equal to 80 ± 30. The oxygen lines were studied as well (green to red line intensity ratios and widths), confirming that H 2 O is the main parent molecule that photodissociates to produce oxygen atoms. This suggests that this comet has a high CO 2 abundance. Relative production rates for C 2 and NH 2 were computed, but we found no significant deviation from a typical NH 2 /C 2 ratio.

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Section: [Oi] Linessupporting

confidence: 94%

High-resolution spectra of comet C/2013 R1 (Lovejoy)

Rousselot

Decock

Корсун

et al. 2015

A&A

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“…The field-of-view of the image is 9 × 9 . ∼6000 Å) (Capria et al 2010;Brown et al 1996;Combi & Delsemme 1980). For the subsequent analysis, we used the R C -band images because they are more sensitive than I C -band images while remaining less contaminated by gaseous emission than are g -band images.…”

Section: The Colormentioning

confidence: 99%

Outbursting Comet P/2010 V1 (Ikeya-Murakami): A Miniature Comet Holmes

Ishiguro

Jewitt

Hanayama

et al. 2014

ApJ

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The short-period comet P/2010 V1 (Ikeya-Murakami, hereafter "V1") was discovered visually by two amateur astronomers. The appearance of the comet was peculiar, consisting of an envelope, a spherical coma near the nucleus and a tail extending in the anti-solar direction. We investigated the brightness and the morphological development of the comet by taking optical images with ground-based telescopes. Our observations show that V1 experienced a large-scale explosion between UT 2010 October 31 and November 3. The color of the comet was consistent with the Sun (g − R C = 0.61 ± 0.20, R C − I C = 0.20 ± 0.20, and B − R C = 0.93 ± 0.25), suggesting that dust particles were responsible for the brightening. We used a dynamical model to understand the peculiar morphology, and found that the envelope consisted of small grains (0.3-1 μm) expanding at a maximum speed of 500 ± 40 m s −1 , while the tail and coma were composed of a wider range of dust particle sizes (0.4-570 μm) and expansion speeds 7-390 m s −1 . The total mass of ejecta is ∼5 × 10 8 kg and kinetic energy ∼5 × 10 12 J. These values are much smaller than in the historic outburst of 17P/Holmes in 2007, but the energy per unit mass (1 × 10 4 J kg −1 ) is comparable. The energy per unit mass is about 10% of the energy released during the crystallization of amorphous water ice suggesting that crystallization of buried amorphous ice can supply the mass and energy of the outburst ejecta.

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“…Based on the theoretical work of Festou & Feldman (1981) green to red-doublet emission intensity ratio (hereafter G/R ratio) of 0.1 has customarily been used as a benchmark to confirm the parent source of these prompt emissions as H 2 O in several comets observed around 1 au from the Sun (Cochran 1984(Cochran , 2008Morrison et al 1997;Zhang et al 2001;Cochran & Cochran 2001;Furusho et al 2006;Capria et al 2005Capria et al , 2008Capria et al , 2010. The observed G/R ratio of more than 0.1 has been attributed to higher relative abundances of CO 2 and CO (Furusho et al 2006;Capria et al 2010;McKay et al 2012;Decock et al 2013). Since no experimental cross section or yield for the production of O( 1 S) from H 2 O is available in the literature, the calculated photorates of Festou & Feldman (1981) have been questioned by Huestis & Slanger (2006).…”

Section: Introductionmentioning

confidence: 99%

Photochemistry of atomic oxygen green and red-doublet emissions in comets at larger heliocentric distances

Raghuram

Bhardwaj

2014

A&A

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Context. In comets, the atomic oxygen green (5577 Å) to red-doublet (6300, 6364 Å) emission intensity ratio (G/R ratio) of 0.1 has been used to confirm H 2 O as the parent species producing forbidden oxygen emission lines. The larger (>0.1) value of G/R ratio observed in a few comets is ascribed to the presence of higher CO 2 and CO relative abundances in the cometary coma. Aims. We aim to study the effect of CO 2 and CO relative abundances on the observed G/R ratio in comets observed at large (>2 au) heliocentric distances by accounting for important production and loss processes of O( 1 S) and O( 1 D) atoms in the cometary coma. Methods. Recently we have developed a coupled chemistry-emission model to study photochemistry of O( 1 S) and O( 1 D) atoms and the production of green and red-doublet emissions in comets Hyakutake and Hale-Bopp. In the present work we applied the model to six comets where green and red-doublet emissions are observed when they are beyond 2 au from the Sun. Results. The collisional quenching of O( 1 S) and O( 1 D) can alter the G/R ratio more significantly than that due to change in the relative abundances of CO 2 and CO. In a water-dominated cometary coma and with significant (>10%) CO 2 relative abundance, photodissociation of H 2 O mainly governs the red-doublet emission, whereas CO 2 controls the green line emission. If a comet has equal composition of CO 2 and H 2 O, then ∼50% of red-doublet emission intensity is controlled by the photodissociation of CO 2 . The role of CO photodissociation is insignificant in producing both green and red-doublet emission lines and consequently in determining the G/R ratio. Involvement of multiple production sources in the O( 1 S) formation may be the reason for the observed higher green line width than that of red lines. The G/R ratio values and green and red-doublet line widths calculated by the model are consistent with the observation. Conclusions. Our model calculations suggest that in low gas production rate comets the G/R ratio greater than 0.1 can be used to constrain the upper limit of CO 2 relative abundance provided the slit-projected area on the coma is larger than the collisional zone. If a comet has equal abundances of CO 2 and H 2 O, then the red-doublet emission is significantly (∼50%) controlled by CO 2 photodissociation and thus the G/R ratio is not suitable for estimating CO 2 relative abundance.

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High resolution observation of 17P/ Holmes during the outburst event in 2007

Cited by 14 publications

References 28 publications

High-resolution spectra of comet C/2013 R1 (Lovejoy)

High-resolution spectra of comet C/2013 R1 (Lovejoy)

Outbursting Comet P/2010 V1 (Ikeya-Murakami): A Miniature Comet Holmes

Photochemistry of atomic oxygen green and red-doublet emissions in comets at larger heliocentric distances

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