Cometary Orbits Research Articles

Citizen Scientists Discover “Asteroid in a Cometary Orbit” 2010 MK43 has a Comet Tail

We present the discovery of a short, diffuse tail on minor planet 2010 MK43 (alternate designation 2010 RA78)—an object previously identified as an asteroid in a cometary orbit—by volunteers of our Citizen Science program Active Asteroids. Our follow-up investigation revealed eight Dark Energy Camera images showing 2010 MK43 with a tail spanning UT 2024 February 12–UT 2024 February 18 when the object was outbound from perihelion. We now classify 2010 MK43 as a Jupiter-family comet based on its Tisserand parameter with respect to Jupiter T J = 2.888, though our dynamical simulations reveal that, due to frequent close encounters with Jupiter, 2010 MK43 was likely a quasi-Hilda within the last 10 kyr.

New and improved orbits of some historical comets: 6TH and 7TH centuries

Five comets from the 6th century and three from the 7th century are studied. In some cases, new orbital elements are provided, or existing ones are refined to better fit the observations. In addition, comments are presented on specific questions raised by other authors about these historical comets, such as their periodicity, association with meteor showers, or even their mere existence. We consider in particular the cases of C/539 W1 and 1P/607H1 (Halley), both particularly interesting from a historical point of view and for the questions they raise in this regard. Finally, we also examine the proposed membership of some 6th-century comets to the Kreutz Sungrazer group.

Ulysses spacecraft in situ detections of cometary dust trails.

The Ulysses spacecraft was launched in 1990 and, after a Jupiter swing-by in 1992, became the first interplanetary spacecraft orbiting the Sun on a highly inclined trajectory with an inclination of [Formula: see text]. The spacecraft was equipped with an impact ionization dust detector which provided 17 years of in situ dust measurements in interplanetary space from 1990 to 2007. Cometary meteoroid streams (also referred to as trails) exist along the orbits of comets, forming fine structures of the interplanetary dust cloud. We use the Interplanetary Meteoroid Environment for eXploration (IMEX) dust streams in space model (Soja RH et al. 2015 Characteristics of the dust trail of 67P/Churyumov-Gerasimenko: an application of the IMEX model. Astron. Astrophys. 583, A18. (doi:10.1051/0004-6361/201526184)) to predict cometary stream traverses by Ulysses and re-analyse the Ulysses dust dataset in order to identify impacts of cometary stream particles detected during such trail traverses. We identify 19 particles compatible with three Ulysses trail traverses on 12 March 1995, 25-27 April 2001 and 16-19 May 2001. The particle origin is compatible with up to five comets, i.e. 10P/Tempel 2, 146P/Shoemaker-LINEAR, 267P/LONEOS and possibly 45P/Honda-Mrkos-Pajdušáková and P/1999 RO28 (LONEOS). We find a dust spatial density in these trails of approximately [Formula: see text]. The radii of the detected cometary stream particles derived from the dust instrument calibration are in the micrometre range. The in situ analysis of meteoroid trail particles in space, which can be traced back to their source bodies, opens a new opportunity for remote compositional analysis of comets and asteroids without the necessity to send a spacecraft to or even land on these celestial bodies, opening new opportunities for future space missions equipped with in situ dust analyzers. This article is part of the theme issue 'Dust in the Solar System and beyond'.

Analyzing A Planet That Crosses a Small Comet’s Fragment Chain

This study explores the novel concept of a planet intersecting the orbit of a small comet's fragment chain. Utilizing a simple multi-generational model of comet fragmentation, it analyzes the planet's interaction with the comet’s fragment chain and simulates probability distributions for both chain crossing and fragment capture. This model offers insights complementary to impact theories that seek to explain the Younger Dryas boundary. Moreover, the potential presence of cometary material in Earth's orbit due to crossing a comet’s fragment chain could profoundly influence climate patterns, with far-reaching implications for global agriculture and food production.

Observations of comet C/1652 Y1 recorded in Korean histories

Abstract We report the Korean records for comet C/1652 Y1, which have not been introduced in previous studies on historical comets. According to Korean historical documents, this comet, described as bai xing (white star, in literal) or ke xing (guest star, in literal), was observed with the naked eye for 22 days from December 19, 1652 to January 9, 1653. In this study, we first cross-checked the records of comet C/1652 Y1 among Korean documents and presented the translations in the Appendix for future reference. We then compared the Korean observations with the orbital path determined from calculations using the orbital elements provided by Marsden (1983. Catalog of cometary orbit. Hillside: Enslow Publishers). We also compared the illustrations depicted by Weigelius and Schiltero (1653. Commentatio astronomica de cometa novo qui sub finem anni 1652 lumine sub obscuro nobis illuxit. Jenae: Typis Georgii Sengenvvaldi) and by Hevelius (1668. Cometographia, Totam Naturam Cometarum; Exhibens. Gedani: Typis Auctoris, & Sumptibus, Simon Reiniger). We found that the Korean observations show discrepancies with the orbital path calculated by Marsden and the illustration of Weigelius and Schiltero, particularly near the end of the observation period. In conclusion, we believe that this study will contribute to improving the orbital path calculation of comet C/1652 Y1.

Cometary outbursts in the Oort cloud

Comet nuclei in the outer Solar system are constantly irradiated by cosmic rays at low temperatures. Accumulated high concentrations of radicals can undergo fast recombination with significant heating of cometary surface layers. We present the model of comet activity at large heliocentric distances caused by the recombination of radicals. We found that the considered mechanism can cause activity of comets in distant regions of the Solar system, even at the Oort cloud distances. Outbursts in distant comet reservoirs can be a new source of dust and ice particles contributing to the recently discovered anomalous diffuse light in the cosmic extragalactic background optic light and the unexpectedly high flux of dust particles detected by the New Horizons dust counter at the edge of the Kuiper belt. The orbits of small-radii comets in the Oort cloud are highly influenced by cometary outbursts. This effect may account for the observed decrease in the number of small-radius long-period comets.

HD\,7977 and its possible influence on Solar System bodies

In the latest Gaia third data release, one can find extremely small proper motion components for the star HD\,7977. This, together with the radial velocity measurement lead to the conclusion that this star passed very close to the Sun in the recent past. Such a very close approach of a one solar mass star must have resulted in noticeable changes in the motion of all Solar System bodies, especially those on less tight orbits, namely long-period comets (LPCs) and transneptunian objects (TNOs). We estimate and discuss these effects. Our current knowledge on the solar neighbourhood found in the latest Gaia catalogues allowed us to perform numerical integrations and prepare a list of potential stellar perturbers of LPCs. We used this list, made available in the StePPeD database. To study the past motion of LPCs under the simultaneous action of the Galactic potential and passing stars, we used precise original cometary orbits taken from the current CODE catalogue. We examined the reliability of the extremely small proper motion of HD\,7977 and conclude that this star can be an unresolved binary; however, according to the astrometry covering more than a century, the current Gaia data cannot be ruled out. We present the parameters of a very close passage of this star near the Sun. We also show examples of the strong influence of this passage on the past motion of some LPCs. We also discuss the possible influence of this perturber on other Solar System bodies. It is possible that 2.47 Myr ago the one solar mass star HD\,7977 passed as close as 1000 au from the Sun. Such an event constitutes a kind of dynamical horizon for all studies of the past Solar System bodies' dynamics.

Implementation and Application of a Regional Fireball Monitoring Network Based on All-sky Camera Networking

Fireball monitoring network is the main equipment for monitoring impact from small-size near-Earth objects (NEOs), and determining meteorite fall locations. In this paper, a monitoring system using a multi-station distributed all-sky video camera network is proposed, and a regional prototype system has been constructed in Jiangsu and surrounding areas. The main processes of fireball monitoring were implemented, including network control, video capture, data processing, trajectory determination, and orbit calculation. After running for 1 yr, the results show that the limiting apparent magnitude - 1.0 for meteors in the video, and the absolute magnitude exhaustive detection regime can reach around - 2.5. The flux of fireballs is found to be 2.68×10−7 km−2· h−1. The percentages of streams and sporadic meteors are 46% and 54%, respectively, and the fraction of cometary orbits equals 72.9%, while for asteroidal-type it is 27.1%. The statistical results are close to those of the international meteor monitoring networks, which verified the monitoring capability of the network system in practical operation.

Analysis of the first coronagraphic multi-band observations of a sungrazing comet

Context. Between 24 and 25 December 2021 a sungrazing comet (SOHO-4341) approached the Sun, being observed by “classical” visible light (VL) coronagraphs on board the SOHO and STEREO missions, and also by the innovative Metis coronagraph on board the ESA-NASA Solar Orbiter mission in the VL and ultraviolet (UV H I Lyman-α) band. Aims. We show how VL data acquired by the Metis coronagraph can be combined with those provided by other space-based coronagraphs to reconstruct the comet orbit, but also to provide information on the dust composition from the polarized VL emission. Moreover, we show how the UV emission can be employed to measure local plasma parameters of the ambient solar wind. Methods. By using the comet positions tracked with VL Metis images (with spatial resolution that is four times better than UV), the UV images (with a time cadence that is five times faster than VL) have been coaligned to maximize the signal-to-noise ratio in the UV band. The local electron density ne was measured from the observed exponential decay of the UV Lyman-α intensity along the tail, while the solar wind speed vwind was measured from the UV Lyman-α tail inclination with respect to the cometary orbital path deprojected in 3D. Moreover, the proton kinetic temperature Tk was also obtained by the aperture angle of the UV Lyman-α tail. Results. When the comet was at an average heliocentric distance of 14.3 R⊙, the comet had a radial speed of 155 km s−1 and a tangential speed of 59 km s−1. The comet had a UV Lyman-α tail extending in the anti-solar direction over more than 1.5 R⊙. From the analysis of the tail shape in UV we obtained the local solar wind speed (vwind = 190 km s−1), electron density (ne = 1.5 × 104 cm−3), and proton temperature (Tk = 1.2 × 106 K). Moreover, theoretical analysis of the measured UV Lyman-α intensity allowed us to estimate the radius of the cometary nucleus (Rcom = 65 m) and the water outgassing rate (QH2O = 4.8 × 1028 molec s−1). Conclusions. These results show that sungrazing comets are unique “local probes” for the ambient coronal plasma, providing measurements that are not as affected by the line-of-sight integration effects as those provided by remote sensing instruments, in regions of the Heliosphere that are not explored in situ by the ongoing space missions.

Non-gravitational Mechanism of Comets’ Ejection from the Oort Cloud Due to Cometary Outbursts

Cometary nuclei located in the Oort cloud accumulate high concentration of radicals in surface layers under cosmic ray irradiation at low temperatures. Recombination of radicals induced by an increase in the surface temperature of a comet by a close passing star, O/B stars, or nearby supernovae leads to the heating of the ice layer with the releasing of volatiles from the amorphous ice. When high gas pressure builds up beneath the cometary surface, dust and gas are ejected. The resulting jet of gas and dust can change the comet’s orbit in the Oort cloud. The studied non-gravitational mechanism can effectively expel comets with a radius of ≤1 km from the Oort cloud into the inner part of the Solar system. The total effect of cometary outbursts on the stability of cometary orbits during the evolution of Solar system can result in a decrease in the number of long-period small-radius comets.

Recurring Activity Discovered on Quasi-Hilda 2009 DQ118

We have discovered two epochs of activity on quasi-Hilda 2009 DQ118. Small bodies that display comet-like activity, such as active asteroids and active quasi-Hildas, are important for understanding the distribution of water and other volatiles throughout the solar system. Through our NASA Partner Citizen Science project, Active Asteroids, volunteers classified archival images of 2009 DQ118 as displaying comet-like activity. By performing an in-depth archival image search, we found over 20 images from UT 2016 March 8–9 with clear signs of a comet-like tail. We then carried out follow-up observations of 2009 DQ118 using the 3.5 m Astrophysical Research Consortium Telescope at Apache Point Observatory, Sunspot, New Mexico, USA and the 6.5 m Magellan Baade Telescope at Las Campanas Observatory, Chile. These images revealed a second epoch of activity associated with the UT 2023 April 22 perihelion passage of 2009 DQ118. We performed photometric analysis of the tail and find that it had a similar apparent length and surface brightness during both epochs. We also explored the orbital history and future of 2009 DQ118 through dynamical simulations. These simulations show that 2009 DQ118 is currently a quasi-Hilda and that it frequently experiences close encounters with Jupiter. We find that 2009 DQ118 is currently on the boundary between asteroidal and cometary orbits. Additionally, it has likely been a Jupiter family comet or Centaur for much of the past 10 kyr and will be in these same regions for the majority of the next 10 kyr. Since both detected epochs of activity occurred near perihelion, the observed activity is consistent with sublimation of volatile ices. 2009 DQ118 is currently observable until ∼mid-October 2023. Further observations would help to characterize the observed activity.

Explanation of the Anomalous Outburst Activity of Comet 29P/Schwassmann–Wachmann 1: The Hypothesis about the Existence of Large Satellites

We explain the anomalous outburst activity of comet 29P/Schwassmann–Wachmann 1 by the existence of satellites touching the surface of the comet nucleus at the pericenters of their orbits. It is assumed that the satellites move in eccentric orbits and a large amount of dust, the reflection of light from which causes periodic outbursts in brightness (BAA 2023), is ejected as a result of their collisions with the dust layer of the nucleus. Depending on the depth of penetration of the satellites into the dust layer, outbursts in comet brightness of various intensities occur. An improvement of the comet orbit by invoking positional observations allows the preferred direction of the ejection of material to be determined from the photocenter offset, which we interpret as the direction of the velocity vector of the largest satellite at the pericenter. The results of our numerical simulations of the ejection and subsequent motion of dust particles caused by the contact of the satellite with the dust layer of the comet nucleus explain the formation of the structures observed in the comet: the dust jets and their mirror symmetry as well as the extent of the region of material ejection from the surface of the comet nucleus.

The Spectrum and Orbit of a Fireball Producing Mesospheric Irregularity and Implications for Meteor Mass Deposition

The physical properties of meteoroids producing meteor plasma non-field-aligned irregularities (NFAI) in the Earth’s atmosphere are poorly known. Here we report a complete picture of a fireball and mesospheric NFAI that it produced for the first time. Simultaneous radar and optical observations were made by the recently completed facility, Meteor and ionospheric Irregularity Observation System. The observations show that the mesospheric NFAI were clustered into three patches where the optical meteor flares took place, instead of being generated continuously along the whole meteor path. It is very likely that nanometer-or-larger-sized dust particles could be directly generated via meteoroid fragmentation at the flaring points and thus promote the generation of NFAI patches. The properties of the parent meteoroid show a chondrite type and a Jupiter family comet orbit, with Na/Mg and Fe/Mg intensity ratios of 1.5 and 1, respectively, photometric mass of about 4 g, and fragmentation strengths of around 10–74 kPa. The results suggest that the direct generation of dust particles, which was previously observed in the atmospheric disintegration of a kiloton-scale meteoroid, could be extended to the much smaller gram-scale meteoroids. Since meteoroids having such characteristics or more fragile material are not unusual, further studies leading to a better understanding of meteor mass deposition in the upper atmosphere, which consider the dust particles directly generated via gram-scale meteoroid fragmentation, are extremely important.

Referencias al cometa Halley desde el observatorio de Cádiz

This paper presents the history of the observations of Halley's comet, in its first scheduled appearance, which were made from the Observatory of Cádiz. A history that links Cadiz with important names: Edmund Halley, who went to Isaac Newton to check the comet's orbit; Jorge Juan and the creation of the Cadiz Observatory which his friend Luis Godin would direct; important astronomers such as Joseph-Nicolas Delisle, who talked to Halley in London and was interested in his predictions, and his disciple the astronomer Charles Messier, who was nicknamed the comet hunter, due to the number of comets he described. Godin, who was himself a fellow astronomy student of Delisle, tracked Halley's comet from the Cadiz observatory, and it is recorded that these observations were taken and sent to Delisle. At a time when data collection was manual, as was the copying of the data and the corresponding annotations; and at a time when the transfer of information was not like e-mails, but was done by horse-drawn carriage, the guarantee that this information reached so many kilometres away could only be given in a later publication. That ratification is the one presented in this article, which completes the link between the Observatory of Cádiz and Halley's comet.

Long-period dynamical evolution of the meteoroid stream originating in comet 21P/Giacobini-Zinner

We investigated the dynamical evolution of the meteoroid stream originating in the nucleus of comet 21P/Giacobini-Zinner. We created 20 partial models, in each assuming 10,000 test particles, and fixed values for the evolutionary time and the strength of the Poynting–Robertson effect. These models provided a “mosaic” with which to map the entire stream. We confirmed that the orbit of the parent comet and the orbits of the test particles, representing the meteoroids, evolved rapidly. This fast evolution resulted in a relatively short duration (up to approx. 1000 years) of the orbital concentrations of the meteoroids that could be identified as the meteor showers. We confirmed the relationship between comet 21P and the October Draconid meteor shower, #9. In addition to this shower, we predicted another five showers related to the comet. Four of these showers were also identified with their real counterparts. Some identifications were multiple. Specifically, we further found an association, or indication of association of 21P, with the ι-Cygnids, #525, August β-Aquariids, #474, June ξ1-Sagittariids, #861, ξ2-Capricornids, #623, Northern σ-Sagittariids, #167, α-Capricornids, #1, Daytime Capricornids-Sagittariids, #115, and ν-Draconids, #220.

Main Belt Comets and other “Interlopers” in the Solar System

According to traditional ideas about the formation of the Solar System starting from a protoplanetary disk of gas and dust, a well-defined distribution of planets and minor bodies is expected: (a) volatile-poor rocky bodies (terrestrial planets and asteroids) in the inner part of the Solar System and (b) volatile-rich objects (gaseous giant planets, comets, Centaurs, and trans-Neptunian objects) in the outer part. All these bodies are expected to orbit near a plane (the ecliptic) coinciding with that of the protoplanetary disk. However, in the modern Solar System many bodies are present that do not respect this simplistic expectation. First of all, there are the so-called Main Belt Comets, apparently asteroidal objects that show an activity similar to that of comets. In addition, there is an object (and several others very probably exist), which, despite its S-type spectrum characteristic of rocky bodies, is found on a cometary orbit. Finally, there are many asteroids on very inclined orbits with respect to the ecliptic. These very interesting groups of objects, which, according to the traditional point of view, could be collectively seen as some sort of “interlopers” of the Solar System, will be discussed in this review, which offers descriptions of their properties and their likely origin. In this respect, the possibility is discussed that many active asteroids (such as those belonging to the Taurid Complex) are the result of the fragmentation of large comets that occurred in the relatively recent past.

New and improved orbits of historical comets: Late 4th and 5th century

Since as early as the 19th century, many scholars have devoted themselves to the calculation of sets of orbital elements for particular historical comets. In many cases, these studies have led to proposing orbits that have given satisfactory answers to contemporary observations or later reports about these celestial bodies. As new records or improved translations of existing sources appear, the already calculated orbits can be refined, or even new ones can be achieved. In this paper we focus on historical observations from Eastern and European countries in the late 4th and 5th centuries to suggest new determinations of orbital elements for some of these comets, or, where appropriate, to discuss or improve existing ones. We will also carry out a separate study of comets from the years AD422–423 and AD467, which have been suggested as the parent comets of the Kreutz system of sungrazer comets.

The impact hazard of near-Sun comets

ABSTRACT There are several groups of comets with perihelion near the solar surface known. Of these, the Marsden and Kracht groups move in orbits situated in a spatial corridor of the daytime Arietid meteoroid stream. The orbits of comets of the Meyer group are not very different from those of the Marsden and Kracht groups; for the purpose of our study, we thus consider a common Meyer–Marsden–Kracht (MMK) group. Since Arietids pass close to the Earth’s orbit, comets of the MMK group must also do so. We study the close approaches of the orbits of these comets with regard to the proximity of the orbit of our planet and estimate an impact hazard. We found a concentration of approaches within an interval of solar longitude from ∼72○–84○ (between June 2 and June 15). The mean time between two collisions of an MMK comet and Earth is estimated to be one to two million years, assuming a steady state during that period.

Comet-Asteroid Classification Among Orbits of Sporadic Meteoroids Observed by BRAMON Between 2014 and 2021

Abstract The Brazilian Meteor Observation Network (BRAMON) is a TV meteor detection network that has been implemented in Brazil since 2014. The BRAMON data made it possible to determine the high-quality orbits of 630 sporadic meteors observed between 2014 and 2021. Using criteria from Jopek & Williams, we assign each of these meteors an asteroidal or cometary origin. Cometary type orbits correspond to slightly more than 60% of sporadic meteors of our sample, a similar percentage to that obtained from other meteor surveys when considering the same magnitude range.

Possible Activity in 468861 (2013 LU28)

Abstract Manx comets are objects on long-period comet orbits that are inactive as they approach perihelion. They are of particular interest because they may help constrain solar system formation models. 2013 LU28 was discovered as an inactive asteroidal object on 2013 June 8 at a heliocentric distance of 21.8 au. Images and photometric data were obtained of 2013 LU28 from multiple telescopes from pre-discovery data in 2010 until the present. Its spectral reflectivity is consistent with typical organic-rich comet surfaces with colors of g ′ − r ′ = 0.97 ± 0.02, r ′ − i ′ = 0.43 ± 0.02, and r ′ − z ′ = 0.65 ± 0.03, corresponding to a spectral reflectivity slope of 30 ± 3%/100 nm. There is no obvious indication of dust coma in deep stacked images. We estimate the nucleus radius to be ∼55.7 ± 0.3 km assuming an albedo of 4%. This is much smaller than the 1σ upper limits on the nucleus size of 79.9 km from the NEOWISE survey assuming the same albedo, since the NEOWISE survey is not very sensitive to objects this small at this distance. The heliocentric light curve suggests possible activity between r ∼ 17 and 13 au where 2013 LU28 is brighter than expected. This is consistent with outgassing from CO or CO2. Using surface brightness profiles, we estimate an upper limit of ∼0.01 kg s−1 for micron-sized dust that can be produced without us detecting it for the inactive portion of the light curve, and upper limits of ∼1 kg s−1 for CO and ∼1.5 kg s−1 for CO2 between 20 and 14.7 au.