Interstellar Visitors: A Physical Characterization of Comet C/2019 Q4 (Borisov) with OSIRIS at the 10.4 m GTC

León, J. de; Licandro, J.; Serra, M.; Cabrera-Lavers, A.; Serra, J. Font; Scarpa, Riccardo; Marcos, C. de la Fuente; Marcos, R. de la Fuente

doi:10.3847/2515-5172/ab449c

Cited by 36 publications

(36 citation statements)

References 5 publications

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“…Our photometric measurements give a consistent g′-r′ colour index, with an average value of 0.66 ± 0.01 mag. The colour is slightly redder than the solar g′-r′ = 0.45 ± 0.02 mag 19 and implies a positive spectral slope S′ ~ 12.5% per 100 nm (see Methods), in good agreement with an independent spectroscopic determination 20 . Within the errors, the same colour is obtained for other photometric apertures as well (we made measurements for the apertures ranging from 3,000 to 15,000 km in radius), implying a uniform colour of the coma.…”

supporting

confidence: 77%

Initial characterization of interstellar comet 2I/Borisov

et al. 2019

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Interstellar comets penetrating through the Solar System had been anticipated for decades 1,2 . The discovery of asteroidal-looking 'Oumuamua 3,4 was thus a huge surprise and a puzzle. Furthermore, the physical properties of the 'first scout' turned out to be impossible to reconcile with Solar System objects 4-6 , challenging our view of interstellar minor bodies 7,8 . Here, we report the identification and early characterization of a new interstellar object, which has an evidently cometary appearance. The body was discovered by Gennady Borisov on 30 August 2019 UT and subsequently identified as hyperbolic by our data mining code in publicly available astrometric data. The initial orbital solution implies a very high hyperbolic excess speed of ~32 km s −1 , consistent with 'Oumuamua 9 and theoretical predictions 2,7 . Images taken on 10 and 13 September 2019 UT with the William Herschel Telescope and Gemini North Telescope show an extended coma and a faint, broad tail. We measure a slightly reddish colour with a g′-r′ colour index of 0.66 ± 0.01 mag, compatible with Solar System comets. The observed morphology is also unremarkable and best explained by dust with a power-law sizedistribution index of -3.7 ± 1.8 and a low ejection speed (44 ± 14 m s −1 for β = 1 particles, where β is the ratio of the solar gravitational attraction to the solar radiation pressure).The nucleus is probably ~1 km in radius, again a common value among Solar System comets, and has a negligible chance of experiencing rotational disruption. Based on these early characteristics, and putting its hyperbolic orbit aside, 2I/Borisov appears indistinguishable from the native Solar System comets.

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confidence: 77%

Initial characterization of interstellar comet 2I/Borisov

et al. 2019

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“…We note that our independent observations lead to the results similar to [1,[7][8][9]. It has been reported that the reflectance spectrum of 2I/Borisov is similar to that of comets and D-type asteroids seen in the solar system [10]. However, in our spectrum there is no sign of emission lines, especially C2 (4700 Ang.…”

Section: Resultssupporting

confidence: 87%

“…However, we should note that comet ejection is not uncommon, and can happen in the solar system due to the migration of giant planets, as predicted by the Nice model [16][17][18]. Current astrometric data indicate that 2I/Borisov came from and will return to a radiant close to the direction of open star cluster Stock 2 [10]. However, we should note that given its speed (∼30 km/s), Stock 2 would not be at its current location and could not have been the origin of 2I/Borisov after it travelled ∼33,000 years.…”

Section: Resultsmentioning

confidence: 92%

Early Observations of the Interstellar Comet 2I/Borisov

Lee

2019

Geosciences

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2I/Borisov is the second ever interstellar object (ISO). It is very different from the first ISO ’Oumuamua by showing cometary activities, and hence provides a unique opportunity to study comets that are formed around other stars. Here we present early imaging and spectroscopic follow-ups to study its properties, which reveal an (up to) 5.9 km comet with an extended coma and a short tail. Our spectroscopic data do not reveal any emission lines between 4000–9000 Angstrom; nevertheless, we are able to put an upper limit on the flux of the C2 emission line, suggesting modest cometary activities at early epochs. These properties are similar to comets in the solar system, and suggest that 2I/Borisov—while from another star—is not too different from its solar siblings.

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“…The velocity distribution of ejected planetesimals is also of particular interest in regards to the recently observed interstellar objects going through the Solar system (Meech et al 2017;de León et al 2019) or meteors of interstellar origin (Siraj & Loeb 2019). Moreover, such ejections could give rise to high velocity interstellar asteroids (or comets, although we do not consider icy compositions in this paper specifically), and their discovery can potentially pinpoint to such tidal disruption origin.…”

Section: Velocity Distributionmentioning

confidence: 99%

Tidal disruption of planetary bodies by white dwarfs – II. Debris disc structure and ejected interstellar asteroids

Malamud

Perets

2020

Monthly Notices of the Royal Astronomical Society

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We make use of a new hybrid method to simulate the long-term, multiple-orbit disc formation through tidal disruptions of rocky bodies by white dwarfs, at high-resolution and realistic semi-major axis. We perform the largest-yet suite of simulations for dwarf and terrestrial planets, spanning four orders of magnitude in mass, various pericentre distances and semi-major axes between 3 AU and 150 AU. This large phase space of tidal disruption conditions has not been accessible through the use of previous codes. We analyse the statistical and structural properties of the emerging debris discs, as well as the ejected unbound debris contributing to the population of interstellar asteroids. Unlike previous tidal disruption studies of small asteroids which form ring-like structures on the original orbit, we find that the tidal disruption of larger bodies usually forms dispersed structures of interlaced elliptic eccentric annuli on tighter orbits. We characterize the (typically power-law) size-distribution of the ejected interstellar bodies as well as their composition, rotation velocities and ejection velocities. We find them to be sensitive to the depth (impact parameter) of the tidal disruption. Finally, we briefly discuss possible implications of our results in explaining the peculiar variability of Tabby's star, the origin of the transit events of ZTF J0139+5245 and the formation of a planetary core around SDSS J1228+1040.

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Interstellar Visitors: A Physical Characterization of Comet C/2019 Q4 (Borisov) with OSIRIS at the 10.4 m GTC

Cited by 36 publications

References 5 publications

Initial characterization of interstellar comet 2I/Borisov

Initial characterization of interstellar comet 2I/Borisov

Early Observations of the Interstellar Comet 2I/Borisov

Tidal disruption of planetary bodies by white dwarfs – II. Debris disc structure and ejected interstellar asteroids

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