# Dennis Bodewits's research while affiliated with Auburn University and other places

## Publications (285)

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In this chapter, we provide a review of radiative processes in cometary atmospheres spanning a broad range of wavelengths, from radio to X-rays. We focus on spectral modeling, observational opportunities, and anticipated challenges in the interpretation of new observations, based on our current understanding of the atomic and molecular processes oc...
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Large portions of comet 67P/Churyumov–Gerasimenko’s northern hemisphere are blanketed by fallback material consisting of centimeter-sized particles termed the smooth terrains. Observations from the Rosetta mission show that the most drastic transient changes during 67P’s 2015 perihelion passage occurred within a subset of these deposits. However, w...
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The LCO Outbursting Objects Key (LOOK) Project uses the telescopes of the Las Cumbres Observatory (LCO) Network to (1) systematically monitor a sample of previously discovered over the whole sky, to assess the evolutionary state of these distant remnants from the early solar system, and (2) use alerts from existing sky surveys to rapidly respond to...
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Cometary activity may be driven by ices with very low sublimation temperatures, such as carbon monoxide ice, which can sublimate at distances well beyond 20 au. This point is emphasized by the discovery of the Oort cloud comet C/2014 UN 271 (Bernardinelli–Bernstein) and its observed activity out to ∼26 au. Through observations of this comet’s optic...
Preprint
Cometary activity may be driven by ices with very low sublimation temperatures, such as carbon monoxide ice, which can sublimate at distances well beyond 20 au. This point is emphasized by the discovery of Oort cloud comet C/2014 UN$_{271}$ (Bernardinelli-Bernstein), and its observed activity out to $\sim$26 au. Through observations of this comet's...
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The LCO Outbursting Objects Key (LOOK) Project uses the telescopes of the Las Cumbres Observatory (LCO) Network to: (1) to systematically monitor a sample of Dynamically New Comets over the whole sky, and (2) use alerts from existing sky surveys to rapidly respond to and characterize detected outburst activity in all small bodies. The data gathered...
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The Rosetta mission to comet 67P/Churyumov–Gerasimenko found unexpectedly high concentrations of molecular oxygen in its atmosphere. New results show that these concentrations are enhanced by a cycle of trapping and releasing of molecular oxygen just below the comet’s surface.
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The Lyman-Alpha Mapping Project (LAMP) UV spectrograph on board the Lunar Reconnaissance Orbiter observed comet C/2013 A1 (Siding Spring) from lunar orbit at closest approach. On 2014 September 5, Siding Spring came within ∼0.89 au of the Earth–Moon system and provided an opportunity for LAMP to contribute to the broader campaign of observations. T...
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In this paper, we present an analysis of X-ray and optical/ultraviolet (UV) data from the favorable (Δ ∼ 0.077 au) 2018 apparition of comet 46P/Wirtanen. The comet was observed during three different epochs (before, during, and after perihelion) over a 1.5 month period using the X-Ray Telescope (XRT) and Ultraviolet and Optical Telescope (UVOT) ins...
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Two papers recently reported the detection of gaseous nickel and iron in the comae of over 20 comets from observations collected over two decades, including interstellar comet 2I/Borisov. To evaluate the state of the laboratory data in support of these identifications, we reanalyzed archived spectra of comet C/1996 B2 (Hyakutake), one of the neares...
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The excitation of nitromethane (CH3NO2), which is an important propellant and prototypic molecule for large class of explosives, has been investigated by electron impact and subsequent emission of photons in the UV‐VIS spectral region between 300 nm and 670 nm. Emission spectrum of nitromethane was recorded at an electron energy of 50 eV. New disso...
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We present preliminary results from the Palomar Transient Factory (PTF) uniform sample of short period comets (SPCs) and long period comets (LPCs), captured between September 2009 and March 2013. We study their dynamical and physical properties in relation to their activity for a better understanding of cometary evolution. This observing campaign w...
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Cometary activity is a manifestation of sublimation-driven processes at the surface of nuclei. However, cometary outbursts may arise from other processes that are not necessarily driven by volatiles. In order to fully understand nuclear surfaces and their evolution, we must identify the causes of cometary outbursts. In that context, we present a st...
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Molecular cations are present in various astronomical environments, most notably in cometary atmospheres and tails where sunlight produces exceptionally bright near-UV to visible transitions. Such cations typically have longer-wavelength and brighter electronic emission than their corresponding neutrals. A robust understanding of their near-UV to v...
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\noindent Recently, it has been discovered that gaseous nickel and iron is present in most comets. To evaluate the state of the laboratory data in support of these identifications, we re-analyzed archived spectra of comet C/1996 B2 (Hyakutake), one of the nearest and brightest comets of the last century, using a combined experimental and computatio...
Preprint
Full-text available
Cometary activity is a manifestation of sublimation-driven processes at the surface of nuclei. However, cometary outbursts may arise from other processes that are not necessarily driven by volatiles. In order to fully understand nuclear surfaces and their evolution, we must identify the causes of cometary outbursts. In that context, we present a st...
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The detection of iron and nickel vapours in a broad range of Solar System comets, and of nickel vapour in a comet from outside the Solar System, provides a glimpse into the organic chemistry of young planetary systems. Emission spectra of pure metal atoms detected in cometary comae.
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To date, at least three comets—2I/Borisov, C/2016 R2 (PanSTARRS), and C/2009 P1 (Garradd)—have been observed to have unusually high CO concentrations compared to water. We attempt to explain these observations by modeling the effect of drifting solid (ice and dust) material on the ice compositions in protoplanetary disks. We find that, independent...
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A major upgrade to the NIRSPEC instrument at the Keck II telescope was successfully completed in time for near-infrared spectroscopic observations of comet 46P/Wirtanen during its exceptionally close flyby of Earth in 2018 December. These studies determined the abundances of several volatiles, including C 2 H 2 , C 2 H 6 , CH 3 OH, NH 3 , HCN, H 2...
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We observed the episodically active asteroid (6478) Gault in 2020 with multiple telescopes in Asia and North America and found that it is no longer active after its recent outbursts at the end of 2018 and the start of 2019. The inactivity during this apparition allowed us to measure the absolute magnitude of Gault of H_r = 14.63 ± 0.02, G_r = 0.21...
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To date, at least three comets -- 2I/Borisov, C/2016 R2 (PanSTARRS), and C/2009 P1 (Garradd) -- have been observed to have unusually high CO concentrations compared to water. We attempt to explain these observations by modeling the effect of drifting solid (ice and dust) material on the ice compositions in protoplanetary disks. We find that, indepe...
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We observed Episodically Active Asteroid (6478) Gault in 2020 with multiple telescopes in Asia and North America and have found that it is no longer active after its recent outbursts at the end of 2018 and start of 2019. The inactivity during this apparation allowed us to measure the absolute magnitude of Gault of H_r = 14.63 +/- 0.02, G_r = 0.21 +...
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Far-ultraviolet observations of comets yield information about the energetic processes that dissociate the sublimated gases from their primitive surfaces. Understanding which emission processes are dominant, their effects on the observed cometary spectrum, and how to properly invert the spectrum back to the composition of the presumably pristine su...
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We obtained broad- and narrowband images of the hyperactive comet 46P/Wirtanen on 33 nights during its 2018/2019 apparition, when the comet made a historic close approach to the Earth. With our extensive coverage, we investigated the temporal behavior of the comet on both seasonal and rotational timescales. We used CN observations to explore the co...
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We measured the degree of linear polarization P of comet C/2018 V1 (Machholz-Fujikawa-Iwamoto) with the broadband Johnson V filter in mid-November of 2018. Within a radius of \r{ho}=17,000 km of the inner coma, we detected an extremely low linear polarization at phase angles from 83 to 91.2 degree and constrained the polarization maximum to Pmax =...
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Far ultraviolet observations of comets yield information about the energetic processes that dissociate the sublimated gases from their primitive surfaces. Understanding which emission processes are dominant, their effects on the observed cometary spectrum, and how to properly invert the spectrum back to composition of the presumably pristine surfac...
Preprint
We obtained broadband and narrowband images of the hyperactive comet 46P/Wirtanen on 33~nights during its 2018/2019 apparition, when the comet made an historic close approach to the Earth. With our extensive coverage, we investigated the temporal behavior of the comet on both seasonal and rotational timescales. CN observations were used to explore...
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We present visible and mid-infrared imagery and photometry of temporary Jovian co-orbital comet P/2019 LD2 taken with HST/WFC3, Spitzer/IRAC, the GROWTH telescope network, visible spectroscopy from Keck/LRIS and archival ZTF observations taken between 2019 April and 2020 August. Our observations indicate that the nucleus of LD2 has a radius between...
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We present visible and mid-infrared imagery and photometry of Jovian co-orbital comet P/2019 LD$_2$ (ATLAS) taken with Hubble Space Telescope/WFC3 on 2020 April 1, Spitzer Space Telescope/IRAC on 2020 January 25, Zwicky Transient Facility between 2019 April 9 and 2019 Nov 8 and the GROWTH telescope network from 2020 May to July, as well as visible...
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We present visible and mid-infrared imagery and photometry of Jovian co-orbital comet P/2019 LD₂ (ATLAS) taken with Hubble Space Telescope/WFC3 on 2020 April 1, Spitzer Space Telescope/IRAC on 2020 January 25, Zwicky Transient Facility between 2019 April 9 and 2019 Nov 8 and the GROWTH telescope network from 2020 May to July, as well as visible spe...
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Exocomets are small bodies releasing gas and dust which orbit stars other than the Sun. Their existence was first inferred from the detection of variable absorption features in stellar spectra in the late 1980s using spectroscopy. More recently, they have been detected through photometric transits from space, and through far-IR/mm gas emission with...
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We present time-resolved visible spectrophotometry of minimoon 2020 CD₃, the second asteroid known to become temporarily captured by the Earth-Moon system's gravitational field. The spectrophotometry was taken with Keck I/LRIS between wavelengths 434 nm and 912 nm in B, g, V, R, I and RG850 filters as it was leaving the Earth-Moon system on 2020 Ma...
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Near-Earth asteroid population models predict the existence of asteroids located inside the orbit of Venus. However, despite searches up to the end of 2019, none have been found. Here we report the discovery by the Zwicky Transient Facility of the first known asteroid located inside of Venus' orbit, 2020 AV₂, possessing an aphelion distance of 0.65...
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Near-Earth asteroid population models predict the existence of asteroids located inside the orbit of Venus. However, despite searches up to the end of 2019, none have been found. Here we report the discovery by the Zwicky Transient Facility of the first known asteroid located inside of Venus' orbit, 2020 AV$_2$, possessing an aphelion distance of 0...
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With the first detection of HeH+ in nearby interstellar space, various molecular ionization and recombination processes are now being calculated to better understand the dynamics of the first molecule in the universe. We use a configuration-average distorted-wave method to compute the photon and electron ionization cross sections of HeH+ based on a...
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Interstellar comets offer direct samples of volatiles from distant protoplanetary disks. 2I/Borisov is the first notably active interstellar comet discovered in our Solar System1. Comets are condensed samples of the gas, ice and dust that were in a star’s protoplanetary disk during the formation of its planets, and inform our understanding on how c...
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We present time-resolved visible spectrophotometry of minimoon 2020 CD$_3$, the second asteroid known to become temporarily captured by the Earth-Moon system's gravitational field. The spectrophotometry was taken with Keck I/LRIS between wavelengths 434 nm and 912 nm in $B$, $g$, $V$, $R$, $I$ and RG850 filters as it was leaving the Earth-Moon syst...
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Telescope and detector developments continuously enable deeper and more detailed studies of astronomical objects. Larger collecting areas, improvement in dispersion and detector techniques, and higher sensitivities allow detection of more molecules in a single observation, at lower abundances, resulting in better constraints of the targets physical...
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We here study the transfer process of material from one hemisphere to the other (deposition of airfall material) on an active comet nucleus, specifically 67P/Churyumov–Gerasimenko. Our goals are to: 1) quantify the thickness of the airfall debris layers and how it depends on the location of the target area, 2) determine the amount of H2O and CO2 ic...
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We advocate for the realization of volatile sample return from various destinations including: small bodies, the Moon, Mars, ocean worlds/satellites, and plumes. As part of recent mission studies (e.g., Comet Astrobiology Exploration SAmple Return (CAESAR) and Mars Sample Return), new concepts, technologies, and protocols have been considered for s...
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We review the importance of recent UV observations of solar system targets and discuss the need for further measurements, instrumentation and laboratory work in the coming decade. In the past decade, numerous important advances have been made in solar system science using ultraviolet (UV) spectroscopic techniques. Formerly used nearly exclusively f...
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Exocomets are small bodies releasing gas and dust which orbit stars other than the Sun. Their existence was first inferred from the detection of variable absorption features in stellar spectra in the late 1980s using spectroscopy. More recently, they have been detected through photometric transits from space, and through far-IR/mm gas emission with...
Preprint
Full-text available
The study of comets affords a unique window into the birth, infancy, and subsequent history of the solar system. There is strong evidence that comets incorporated pristine interstellar material as well as processed nebular matter, providing insights into the composition and prevailing conditions over wide swaths of the solar nebula at the time of p...
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Small bodies are time-capsules of different eras of solar system history from the most primitive materials within the solar system to evolved pieces of larger bodies. A small body sample return program is an essential component of small body exploration, and such a program should include opportunities for both missions and laboratory analysis.
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We present visible and near-infrared photometric and spectroscopic observations of interstellar comet 2I/Borisov taken from 2019 September 10 to 2019 November 03 using the GROWTH collaboration, the Apache Point Observatory ARC 3.5 m and the NASA/IRTF 3.0 m combined with post and pre-discovery observations of 2I obtained by the Zwicky Transient Faci...
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We present a preliminary analysis of comet P/2019 LM₄ (Palomar) as observed by the Zwicky Transient Facility (ZTF) survey in 2019 and 2020. We find that the discovery of the comet in 2019 and the recovery in 2020 is largely attributed to two separate outbursts that are ≳2 and ≳3.9 mag in strength. The two outbursts occurred between the end of April...
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We present a preliminary analysis of comet P/2019 LM$_4$ (Palomar) as observed by the Zwicky Transient Facility (ZTF) survey in 2019 and 2020. We find that the discovery of the comet in 2019 and the recovery in 2020 is largely attributed to two separate outbursts that are $\gtrsim2$ and $\gtrsim3.9$ mag in strength. The outbursts occurred around th...
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Observations of comet nuclei indicate that the main constituent is a mix of ice and refractory materials characterized by high porosity (70–75%) and low bulk strength (10 ⁻⁴ –10 ⁻⁶ MPa); however, the nature and physical properties of these materials remain largely unknown. By combining surface inspection of comet 67P/Churyumov–Gerasimenko and three...
Preprint
Full-text available
Interstellar comets offer direct samples of volatiles from distant protoplanetary disks. 2I/Borisov is the first notably active interstellar comet discovered in our solar system[1]. Comets are condensed samples of the gas, ice, and dust that were in a star's protoplanetary disk during the formation of its planets and inform our understanding on how...
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Aims. We provide a measurement of the seasonal evolution of the dust deposit erosion and accretion in the Hapi region of comet 67P/Churyumov-Gerasimenko with a vertical accuracy of 0.2–0.9 m. Methods. We used OSIRIS Narrow Angle Camera images with a spatial scale of lower than 1.30 m px−1 and developed a tool to monitor the time evolution of 22 bou...
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Full-text available
Aims. We provide a measurement of the seasonal evolution of the dust deposit erosion and accretion in the Hapi region of comet 67P/Churyumov-Gerasimenko with a vertical accuracy of 0.2–0.9 m. Methods. We used OSIRIS Narrow Angle Camera images with a spatial scale of lower than 1.30 m px ⁻¹ and developed a tool to monitor the time evolution of 22 bo...