Unusual polarimetric properties for interstellar comet 2I/Borisov

Bagnulo, S.; Cellino, A.; Kolokolova, L.; Nežič, Rok; Santana-Ros, T.; Borisov, G.; Christou, Apostolos; Bendjoya, Philippe; Devogèle, Maxime

doi:10.1038/s41467-021-22000-x

Cited by 22 publications

(20 citation statements)

References 68 publications

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“…However, C/1995 O1 (Hale-Bopp) around its perihelion (25 • < α < 35 • ) always shows excessively high P r values compared to the majority of comets. P r of 2I/Borisov shows a typical value in the NPB but as high as those of Hale-Bopp in the PPB (Bagnulo et al 2021). For other comets, we do not find such a significant difference.…”

Section: Dependence Of the Polarisation Degree On Phase Anglecontrasting

confidence: 69%

“…Fig. 5 shows the P r distribution of cometary dust on the wavelength at the α range of 0 • -35 • adopted from the NASA/PDS comet polarimetric archive (Kiselev et al 2017) and Bagnulo et al (2021). We select data only taken with the narrow-band continuum filters and at multi-wavelength (quasi-)simultaneously (i.e.…”

Section: Dependence Of the Polarisation Degree On Wavelengthmentioning

confidence: 99%

“…Finally, we compare the P r (α) of dust between 67P and other comets. The narrow-band data (or broad-band ones unambiguously proved to be free from gas contamination) taken in the Red domain from the NASA/PDS archive (Kiselev et al 2017) and the data of an extrasolar comet, 2I/Borisov, taken in R F filter (6,550/1,650 Å; Bagnulo et al 2021) are used for this comparative study. Again, the average trend is estimated from Eq.…”

Section: Dependence Of the Polarisation Degree On Phase Anglementioning

confidence: 99%

“…11 for the data whose aperture size ranges from ∼1,000-10,000 km (on average ∼4,000 km in cometocentric distance). We exclude unique comets C/1995 O1 (Hale-Bopp) and 2I/Borisov from the fitting due to their significant P r excess compared to the majority of comets (Hadamcik & Levasseur-Regourd 2003b;Kikuchi 2006;Bagnulo et al 2021) and the large aperture size (for Hale-Bopp). Fig.…”

Section: Dependence Of the Polarisation Degree On Phase Anglementioning

confidence: 99%

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VLT spectropolarimetry of comet 67P: Dust environment around the end of its intense Southern summer

Kwon,

Bagnulo,

Markkanen

et al. 2021

Preprint

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Context. A cornucopia of Rosetta and ground-based observational data sheds light on the evolution of the characteristics of dust particles from comet 67P/Churyumov-Gerasimenko (hereafter 67P) with seasons, implying the different dust environments in the source regions on the surface of the comet. Aims. We aim to constrain the properties of the dust particles of 67P and therefrom diagnose the dust environment of its coma and near-surface layer at around the end of the Southern summer of the comet. Methods. We performed spectropolarimetric observations for 67P dust over 4,000-9,000 Å using the ESO/Very Large Telescope in January-March 2016 (phase angle ranging ∼26 • -5 • ). We examined the optical behaviours of the dust, which, together with Rosetta colour data, were used to search for dust evolution with cometocentric distance. Modelling was also conducted to identify the dust attributes compatible with the results. Results. The spectral dependence of the polarisation degree of 67P dust is flatter than found in other dynamical groups of comets in similar observing geometry. The depth of its negative polarisation branch appears to be a bit shallower than in long-period comets and might be getting shallower as 67P repeats its apparitions. Its dust colour shows a change in slope around 5,500 Å, (17.3 ± 1.4) and (10.9 ± 0.6) % (1,000 Å) −1 for shortward and longward of the wavelength, respectively, which are slightly redder but broadly consistent with the average of Jupiter-Family comets. Conclusions. Observations of 67P dust in this study can be attributed to dust agglomerates of ∼100 µm in size detected by Rosetta in early 2016. A porosity of 60 % shows the best match with our polarimetric results, yielding a dust density of ∼770 kg m −3 . Compilation of Rosetta and our data indicates the dust's reddening with increasing nucleus distance, which may be driven by water-ice sublimation as the dust moves out of the nucleus. We estimate the possible volume fraction of water ice in the initially ejected dust as ∼6 % (i.e. the refractory-to-ice volume ratio of ∼14).

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Section: Dependence Of the Polarisation Degree On Phase Anglecontrasting

confidence: 69%

Section: Dependence Of the Polarisation Degree On Wavelengthmentioning

confidence: 99%

Section: Dependence Of the Polarisation Degree On Phase Anglementioning

confidence: 99%

Section: Dependence Of the Polarisation Degree On Phase Anglementioning

confidence: 99%

See 2 more Smart Citations

VLT spectropolarimetry of comet 67P: Dust environment around the end of its intense Southern summer

Kwon,

Bagnulo,

Markkanen

et al. 2021

Preprint

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“…Recently, Guzik & Drahus (2021) reported a spectroscopic detection of atomic nickel vapor in the coma. Bagnulo et al (2021) presented polarimetric observations that demonstrated that the dust coma had abnormally high polarization compared to Solar System comets. Astrometric analyses of the non-gravitational acceleration are consistent with observed levels of outgassing (Hui et al 2020; de la Fuente Marcos & de la Fuente Marcos 2020; Manzini et al 2020).…”

Section: Introductionmentioning

confidence: 99%

The Population of Interstellar Objects Detectable with the LSST and Accessible for $\textit{In Situ}$ Rendezvous with Various Mission Designs

Hoover¹,

Seligman²,

Payne³

2021

Preprint

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The recently discovered population of interstellar objects presents us with the opportunity to characterize material from extrasolar planetary and stellar systems up close. The forthcoming Rubin Observatory Legacy Survey of Space and Time (LSST) will provide an unprecedented increase in sensitivity to these objects compared to the capabilities of currently operational observational facilities. In this paper, we generate a synthetic population of interstellar objects drawn from their galactic kinematics, and identify the distribution of impact parameters, eccentricities, hyperbolic velocities and sky locations of objects detectable with the LSST. This population is characterized by a clustering of trajectories in the direction of the solar apex and anti-apex, centered at orbital inclinations of ∼ 90 • . We identify the ecliptic or solar apex as the optimal sky locations to search for future interstellar objects as a function of survey limiting magnitude. Moreover, we identify the trajectories of detectable objects that will be reachable for in-situ rendezvous with a dedicated mission with the capabilities of the forthcoming Comet Interceptor or proposed BRIDGE concept. By scaling our fractional population statistics with the inferred spatial number density, we estimate that the LSST will detect of order ∼ 50 interstellar objects over the course of its ∼ 10 year observational campaign. Furthermore, we find that there should be of order ∼ 10 and ∼ 0.05 reachable targets for missions with propulsion capabilities comparable to BRIDGE and Comet Interceptor, respectively. These number estimates will be readily updateable when the number density and size frequency distribution of interstellar objects is better constrained.

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Comet Interceptor Mission

Jones

Snodgrass

Tubiana

et al. 2021

Encyclopedia of Astrobiology

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Here we describe the novel, multi-point Comet Interceptor mission. It is dedicated to the exploration of a little-processed long-period comet, possibly entering the inner Solar System for the first time, or to encounter an interstellar object originating at another star. The objectives of the mission are to address the following questions: What are the surface composition, shape, morphology, and structure of the target object? What is the composition of the gas and dust in the coma, its connection to the nucleus, and the nature of its interaction with the solar wind? The mission was proposed to the European Space Agency in 2018, and formally adopted by the agency in June 2022, for launch in 2029 together with the Ariel mission. Comet Interceptor will take advantage of the opportunity presented by ESA's F-Class call for fast, flexible, low-cost missions to which it was proposed. The call required a launch to a halo orbit around the Sun-Earth L2 point. The mission can take advantage of this placement to wait for the discovery of a suitable comet reachable with its minimum ΔV capability of 600 ms −1 . Comet Interceptor will be unique in encountering and studying, at a nominal closest approach distance of 1000 km, a comet that represents a near-pristine sample of material from the formation of the Solar System. It will also add a capability that no previous cometary mission has had, which is to deploy two sub-probes -B1, provided by the Japanese space agency, JAXA, and B2 -that will follow different trajectories through the coma. While the main probe passes at a nominal 1000 km distance, probes B1 and B2 will follow different chords through the coma at distances of 850 km and 400 km, respectively. The result will be unique, simultaneous, spatially resolved information of the 3-dimensional properties of the target comet and its interaction with the space environment. We present the mission's science background leading to these objectives, as well as an overview of the scientific instruments, mission design, and schedule.

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Unusual polarimetric properties for interstellar comet 2I/Borisov

Cited by 22 publications

References 68 publications

VLT spectropolarimetry of comet 67P: Dust environment around the end of its intense Southern summer

VLT spectropolarimetry of comet 67P: Dust environment around the end of its intense Southern summer

The Population of Interstellar Objects Detectable with the LSST and Accessible for $\textit{In Situ}$ Rendezvous with Various Mission Designs

Comet Interceptor Mission

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