arXiv subjects

Vishnu Reddy

Publications and source records attributed to Vishnu Reddy.

At least 19 recordsLinked to original sources

arXiv2026

Improving Faint Object Detection for Space Situational Awareness with Variational Autoencoders

We present a deep-learning pipeline for enhancing the detection of faint moving objects in optical space situational awareness (SSA) imagery through automated star removal and background reconstruction. Detecting low signal-to-noise ratio (SNR) objects remains extremely challenging in optical observations, particularly in the cislunar (X-GEO) environment, where structured sky backgrounds, dense stellar fields, and scattered moonlight significantly degrade the performance of classical detection algorithms. To address this problem, the proposed pipeline combines a lightweight segmentation network (Tiny-U-Net) to generate stellar masks with a partial-convolution variational autoencoder (astro-VAE), designed to learn the statistical distribution of astronomical backgrounds and perform context-aware inpainting of masked regions. The reconstructed background maps can then be used as a preprocessing step to suppress fixed sources and background inhomogeneities prior to detection. As a proof of concept, the approach is integrated with a shift-and-stack scheme and evaluated on real ground-based telescope observations targeting the X-GEO region. Results demonstrate that the method reconstructs star-free backgrounds with high fidelity, while preserving moving targets and significantly enhancing detectability, thereby providing an effective data-driven preprocessing strategy for faint moving-object detection in optical SSA scenarios.

cs.CV↗

arXiv2026

Size Constraints for the Pre-atmospheric Parent Bodies of Ordinary Chondrites

The study of S-complex near-Earth objects (NEOs), the parent bodies of ordinary chondrites, has shown that they are dominated by asteroids with LL chondrite-like compositions. This is surprising because among the three subtypes of ordinary chondrites (H, L, and LL), LL chondrites are the least common, representing only 10\% of all ordinary chondrite falls. This discrepancy has been attributed to the size of the NEOs studied, which are likely too large to be the immediate precursors of the meteorites that fall on Earth. To test this hypothesis, we obtained near-infrared spectra (0.7-2.5 $\mu$m) of a group of objects with absolute magnitudes 20.0 $\leq$ $H$ $\leq$ 29.2 (sizes $\sim$4-343 m). The sample was divided into subgroups based on their $H$ value, and the composition of the asteroids was determined. We found that the dominance of LL chondrite-like objects disappears at sizes of $\sim$31-49 m. At this size range, asteroids with L chondrite-like compositions become dominant, matching the fraction of L chondrite meteorite falls. In contrast, the fraction of H chondrite-like NEOs was found to be much lower than the proportion of H chondrite falls, even among the smallest objects. We determined an upper size limit of $\sim$18 m for the parent bodies of these meteorites. The same upper limit was established for the pre-atmospheric parent bodies of LL chondrites. These results constitute the first observational evidence for a size dependence in the composition of S-complex NEOs.

astro-ph.EP↗

arXiv2026

Physical Characterization of Moon Impactor 2025-010D

Renewed interest in lunar exploration is creating a growing population of poorly tracked cislunar objects, some of which will ultimately impact the Moon$^{1}$. The ultimate fate of rocket upper stages or failed mission payloads is often unknown and unplanned. Determining the origin and physical properties of such objects will become increasingly important as sustained lunar exploration places humans and infrastructure on the surface$^{2;3;4;5}$. Here we present a ground-based physical and dynamical characterization of 2025-010D, a Falcon 9 upper stage predicted to impact the lunar farside on 2026 August 05. Backward propagation of its orbit independently links the object to the ``Ghost Riders in the Sky'' launch, while visible and near-infrared spectroscopy distinguishes it from natural objects and reveals absorption bands consistent with spacecraft thermal control materials. Photometric lightcurves confirm its elongated shape and reveal an unexpected change of more than 8 s in its $\sim$7 min rotation period during observations. We predict an impact between Bell and Einstein craters at $\sim$2.4 km s$^{-1}$, producing a crater $\sim$40 m in diameter. Since its provenance is independently known, 2025-010D provides a benchmark for identifying and characterizing future cislunar objects of uncertain origin.

astro-ph.EP↗

arXiv2026

JWST Characterization of Earth Quasi-Satellite (469219) Kamo`oalewa

Near-Earth asteroid (469219) Kamo`oalewa is a uniquely stable quasi-satellite of the Earth and a target of the Tianwen-2 spacecraft mission. Here we report observations taken with JWST's NIRSpec instrument in integral field unit (IFU) mode in February 2026. The JWST reflectance spectrum is notably less red (more neutral) from $1.0-2.5$ $\mu m$ than previous ground-based spectrophotometric observations. New observations made with LBT in April 2026, observed and processed similarly to the 2021 observations, find $zJ$ colors in agreement with JWST. Kamo`oalewa's infrared colors appear more similar to S, V, or E-type silicate asteroids and unlike the reddened, space-weathered lunar-like silicates suggested by previous observations. In agreement with the ground-based spectrum, we detect a faint silicate absorption feature at $0.93\pm 0.01$ $\mu m$. We do not detect a 2.0 $\mu m$ silicate absorption. Models of Kamo`oalewa's faint thermal emission (beginning near 4.5 $\mu m$) find a mean diameter of $D=18\pm2\mathrm{m}$ and best-fit visible albedo $p_V = 0.59^{+0.25}_{-0.17}$, with models as low as $p_V = 0.36$ providing adequate model fits. This combination of color, albedo, and absorption bands is similar to oldhamite-bearing enstatite-rich compositions. Kamo`oalewa's brightness variations over the course of the JWST program provides independent confirmation of its rotation period of 27.9 minutes, with an axis ratio $\sim1.4$ ($D\sim15-21$ m).

astro-ph.EP↗

arXiv2026

Ultraviolet Radiation Effects on the Optical Properties of Water-Dominated Exoplanet Hazes

Temperate sub-Neptune and terrestrial exoplanets could contain large inventories of water in various phases, such as water-dominated atmospheres or even oceans. Observations have shown that many exoplanets, including water worlds, likely contain photochemically-generated hazes. Haze particles are a key source of organic matter and may impact the evolution or origin of life; their optical properties are imperative for interpreting observations through theoretical atmospheric modeling. Modelers have thus far assumed haze optical properties that may not represent hazes under sub-Neptune and terrestrial atmospheric conditions. Often orbiting close to M-dwarf stars, these planets receive large amounts of radiation, especially during flaring events, which may accelerate atmospheric escape and affect atmospheric compositions. Here, we present optical constants of experimentally-generated sub-Neptune haze analogs before and after UV irradiation across a broad wavelength range (0.5 to 8 {\mu}m). We find that UV-irradiation alters haze optical constants which become generally more absorbing in this wavelength range, which we hypothesize is due to our sample containing more oxygen-rich absorbing bands post irradiation. We use Virga and PICASO to simulate transmission spectra of potentially hazy water-dominated planets GJ 1214b and LHS 1140b, accounting for irradiated haze layers in their atmospheres. For our GJ 1214b CH4-rich haze modeled case, we see a difference in the N-H feature at 2.6 {\mu}m in the resulting transmission spectrum between irradiated and unaltered haze that should be observable within current JWST capabilities. Broadly, we demonstrate the importance of using more representative optical constants, as they have an impact on current and future atmospheric composition interpretations.

astro-ph.EP↗

arXiv2025

Near-Discovery Observations of Interstellar Comet 3I/ATLAS with the NASA Infrared Telescope Facility

Interstellar Objects are comets and asteroids that formed around other stars but were ejected before they could accrete into exoplanets. They therefore represent a rare opportunity to compare the building blocks of planets in the Solar System to those in other stellar systems. The third Interstellar Object, 3I/ATLAS, is the newest, brightest, potentially largest, and fastest member of this population. We report observations of 3I/ATLAS taken on 2025 July 3 and 4 with the NASA Infrared Telescope Facility just days after its discovery. In r'-band imaging with 'Opihi, we see no obvious lightcurve variability and derive a g'-i' color of 0.98+/-0.03 which is consistent in spectral slope to other near-discovery observations. We obtained the first near-infrared (NIR) reflectance spectrum of 3I/ATLAS with SpeX. The visible color and NIR spectrum show a linear, red visible slope, a somewhat less red slope between 0.7 and 1.1 $\mu{m}$, and a neutral or slightly blue slope at longer wavelengths. Challenges in modeling the reflectivity of 3I may indicate that this comet has a complex grain size distribution, grain compositions unlike Solar system comets, or both. Like 2I/Borisov, there are no obvious signatures of water ice in the coma of 3I/ATLAS. Observations closer to perihelion will help elucidate whether 3I has less water than anticipated or whether the Interstellar Objects might retain and release their ices somewhat differently than Solar System comets do.

astro-ph.EP↗

arXiv2025

Effects of Ultraviolet Radiation on Sub-Neptune Exoplanet Hazes Through Laboratory Experiments

Temperate sub-Neptune exoplanets could contain large inventories of water in various phases, such as water-worlds with water-rich atmospheres or even oceans. Both space-based and ground-based observations have shown that many exoplanets likely also contain photochemically-generated hazes. Haze particles are a key source of organic matter and may impact the evolution or origin of life. In addition, haze layers could provide a mechanism for lower-atmospheric shielding and ultimately atmospheric retention. Often orbiting close to M-dwarf stars, these planets receive large amounts of radiation, especially during flaring events, which may strip away their atmospheres. M-dwarf stars are known to have higher stellar activity than other types of stars, and stellar flares have the potential to accelerate atmospheric escape. In this work, we present results on laboratory investigations of UV radiation effects simulating two different stellar flare energies on laboratory-produced exoplanet hazes made under conditions analogous to water-world atmospheres. We find that both simulated flares altered the overall transmittance and reflectance of the hazes, and higher energy "flares" make those alterations more pronounced. On a larger scale, these laboratory-made hazes show potential signs of degradation over the simulated flaring period. Our results provide insight into the effects that stellar flaring events have on potential exoplanet haze composition and the ability for water-world-like exoplanets to retain their atmospheres.

astro-ph.EP↗

arXiv2025

Spectral Effects of Shock Darkening on Ordinary Chondrite and Howardite, Eucrite, and Diogenite meteorites

Impacts are the most ubiquitous processes on planetary bodies in our solar system. During these impact events, shock waves can deposit enough energy to produce shock-induced darkening in the target material, resulting in an alteration of its spectral properties. This spectral alteration can lead to an ambiguous taxonomic classification of asteroids and an incorrect identification of meteorite analogs. In this study, we investigated the effects of shock darkening on the visible and near-infrared spectra of ordinary chondrites and members of the howardites, eucrites, and diogenites clan. A decrease in albedo and suppression of the absorption bands with increasing shock darkening was observed for all the samples. We found that adding $\gtrsim$50\% of shock-darkened material to an unaltered sample was enough to change the taxonomic classification of an ordinary chondrite from S-complex to C- or X-complex. A similar amount was sufficient to change the taxonomic classification of a eucrite from V-type to O-type, whereas a eucrite composed of 100\% shock-darkened material was classified as a Q-type. We discuss the limitations of using just albedo for taxonomic classification of asteroids, which has implications for future space-based infrared surveys. We also investigated if shock darkening is responsible for a bias against the discovery of near-Earth objects (NEOs) with H and L chondrite-like compositions, which could explain the abundance of LL chondrites among NEOs.

astro-ph.EP↗

arXiv2024

The population of small near-Earth objects: composition, source regions and rotational properties

The study of small ($<$300 m) near-Earth objects (NEOs) is important because they are more closely related than larger objects to the precursors of meteorites that fall on Earth. Collisions of these bodies with Earth are also more frequent. Although such collisions cannot produce massive extinction events, they can still produce significant local damage. Here we present the results of a photometric and spectroscopic survey of small NEOs, which include near-infrared (NIR) spectra of 84 objects with a mean diameter of 126 m and photometric data of 59 objects with a mean diameter of 87 m. We found that S-complex asteroids are the most abundant among the NEOs, comprising $\sim$66\% of the sample. Most asteroids in the S-complex were found to have compositions consistent with LL-chondrites. Our study revealed the existence of NEOs with spectral characteristics similar to those in the S-complex, but that could be hidden within the C- or X-complex due to their weak absorption bands. We suggest that the presence of metal or shock-darkening could be responsible for the attenuation of the absorption bands. These objects have been grouped into a new subclass within the S-complex called Sx-types. The dynamical modeling showed that 83\% of the NEOs escaped from the $\nu_{6}$ resonance, 16\% from the 3:1 and just 1\% from the 5:2 resonance. Lightcurves and rotational periods were derived from the photometric data. No clear trend between the axis ratio and the absolute magnitude or rotational period of the NEOs was found.

astro-ph.EP↗

arXiv2024

The Massalia asteroid family as the origin of ordinary L chondrites

Studies of micrometeorites in mid-Ordovician limestones and Earth's impact craters indicate that our planet witnessed a massive infall of ordinary L chondrite material 466 million years (My) ago (Heck et al. 2017, Schmieder & Kring 2020, Kenkmann 2021) that may have been at the origin of the first major mass extinction event (Schmitz et al. 2019). The breakup of a large asteroid in the main belt is the likely cause of this massive infall. In modern times, material originating from this breakup still dominates meteorite falls (>20% of all falls) (Swindle et al. 2014). Here, we provide spectroscopic observations and dynamical evidence that the Massalia collisional family is the only plausible source of this catastrophic event and of the most abundant class of meteorites falling on Earth today. It is suitably located in the inner belt, at low-inclination orbits, which corresponds to the observed distribution of L-chondrite-like near-Earth objects (NEOs) and of interplanetary dust concentrated at 1.4 degrees (Sykes 1990, Reach et al. 1997).

astro-ph.EP↗

arXiv2024

Grain Size Effects on UV-MIR (0.2-14 micron) Spectra of Carbonaceous Chondrite Groups

Carbonaceous chondrites are among the most important meteorite types and have played a vital role in deciphering the origin and evolution of our solar system. They have been linked to low-albedo C-type asteroids, but due to subdued absorption bands, definitive asteroid-meteorite linkages remain elusive. A majority of these existing linkages rely on fine-grained (typically < 45 micron) powders across a limited wavelength range in the visible to near-infrared (0.35-2.5 microns). While this is useful in interpreting the fine-grained regolith of larger main-belt objects like Ceres, recent spacecraft missions to smaller near-Earth asteroids (NEAs), such as Bennu and Ryugu, have shown that their surfaces are dominated by larger grain size material. To better interpret the surfaces of these smaller, carbonaceous NEAs, we obtained laboratory reflectance spectra of seven carbonaceous chondrite meteorite groups (CI, CM, CO, CV, CR, CK, C2-ungrouped) over the ultraviolet to mid-infrared range (0.2-14 microns). Each meteorite contained five grain size bins (45-1000 microns) to help constrain spectral grain size effects. We find a correlation between grain size and absolute reflectance, spectral slope, band depth, and the Christiansen feature band center. Principal component analysis of grain size variation illustrates a similar trend to lunar-style space weathering. We also show that the Bus-DeMeo asteroid taxonomic classification of our samples is affected by grain size, specifically shifting CM2 Aguas Zarcas from a Ch-type to B-type with increasing grain size. This has implications for the parent body of the OSIRIS-REx target, Bennu. With Aguas Zarcas, we present results from Hapke modeling.

astro-ph.EP↗

arXiv2023

Near-IR Spectral Observations of the Didymos System -- Daily Evolution Before and After the DART Impact, Indicates Dimorphos Originated from Didymos

Ejecta from Dimorphos following the DART mission impact, significantly increased the brightness of the Didymos-Dimorphos system, allowing us to examine sub-surface material. We report daily near-IR spectroscopic observations of the Didymos system using NASA's IRTF, that follow the evolution of the spectral signature of the ejecta cloud over one week, from one day before the impact. Overall, the spectral features remained fixed (S-type classification) while the ejecta dissipated, confirming both Didymos and Dimorphos are constructed from the same silicate material. This novel result strongly supports binary asteroid formation models that include breaking up of a single body, due to rotational breakup of km-wide bodies. At impact time +14 and +38 hours, the spectral slope decreased, but following nights presented increasing spectral slope that almost returned to the pre-impact slope. However, the parameters of the $1~\mu m$ band remained fixed, and no "fresh" / Q-type-like spectrum was measured. We interpret these as follow: 1. The ejecta cloud is the main contributor ($60-70\%$) to the overall light during the $\sim40$ hours after impact. 2. Coarser debris ($\geq 100~\mu m$) dominated the ejecta cloud, decreasing the spectral slope (after radiation pressure removed the fine grains at $\leq10$ hours after impact); 3. after approximately one week, the ejecta cloud dispersed enough to make the fine grains on Didymos surface the dominating part of the light, increasing the spectral slope to pre-impact level. 4. a negligible amount of non-weathered material was ejected from Dimorphos' sub-surface, suggesting Dimorphos was accumulated from weathered material, ejected from Didymos surface.

astro-ph.EP↗

arXiv2023

Spectroscopic Links Among Giant Planet Irregular Satellites and Trojans

We collect near-infrared spectra ($\sim0.75-2.55\ \mu m$) of four Jovian irregular satellites and visible spectra ($\sim0.32-1.00\ \mu m$) of two Jovian irregular satellites, two Uranian irregular satellites, and four Neptune Trojans. We find close similarities between observed Jovian irregular satellites and previously characterized Jovian Trojans. However, irregular satellites' unique collisional histories complicate comparisons to other groups. Laboratory study of CM and CI chondrites show that grain size and regolith packing conditions strongly affect spectra of dark, carbonaceous materials. We hypothesize that different activity histories of these objects, which may have originally contained volatile ices that subsequently sublimated, could cause differences in regolith grain-size or packing properties and therefore drive spectral variation. The Uranian satellites Sycorax and Caliban appear similar to TNOs. However, we detect a feature near 0.7 $\mu m$ on Sycorax, suggesting the presence of hydrated materials. While the sample of Neptune Trojans have more neutral spectra than the Uranian satellites we observe, they remain consistent with the broad color distribution of the Kuiper belt. We detect a possible feature near 0.65-0.70 $\mu m$ on Neptune Trojan 2006 RJ103, suggesting that hydrated material may also be present in this population. Characterizing hydrated materials in the outer solar system may provide critical context regarding the origins of hydrated CI and CM chondrite meteorites. We discuss how the hydration state(s) of the irregular satellites constrains the thermal histories of the interiors of their parent bodies, which may have formed among the primordial Kuiper belt.

astro-ph.EP↗

arXiv2023

Nuclear and Orbital Characterization of the Transition Object (4015) 107P/Wilson-Harrington

Comet 107P/Wilson-Harrington, cross-listed as asteroid 4015, is one of the original transition objects whose properties do not neatly fit into a cometary or asteroidal origin. Discovered in a period of apparently gas-dominated activity in 1949, it was subsequently lost and recovered as the inactive asteroid 1979 VA. We obtained new and re-analyzed archival observations of the object, compared to meteorites, and conducted new orbital integrations in order to understand the nature of this object and to understand where it falls on the asteroid-comet continuum. Wilson-Harrington's reflectance spectrum is approximately neutral from visible to near-infrared wavelengths, but has a reflectance maximum near 0.8-0.9 microns. The object's spectrum is well matched by laboratory spectra of carbonaceous chondrite meteorites like the CM Murchison or the CI Ivuna. The object's phase curve is compatible with either an asteroidal or cometary origin, and its recent orbital history has no periods with high enough temperatures to have altered its surface. While it is possible that some unknown process has acted to change the surface from an originally cometary one, we instead prefer a fundamentally asteroidal origin for Wilson-Harrington which can explain its surface and orbital properties. However, this would require a way to maintain significant (hyper-)volatile supplies on the near-Earth objects beyond what is currently expected. Wilson-Harrington's similar meteorite affinity and possible orbital link to sample return targets (162173) Ryugu and (101955) Bennu suggest that the returned samples from the Hayabusa-2 and OSIRIS-REx missions might hold the key to understanding this object.

astro-ph.EP↗

arXiv2023

Mineralogical Characterization and Phase Angle Study of Two Binary Near-Earth Asteroids, Potential Targets for NASA's Janus Mission

Ground-based characterization of spacecraft targets prior to mission operations is critical to properly plan and execute measurements. Understanding surface properties, like mineralogical composition and phase curves (expected brightness at different viewing geometries) informs data acquisition during the flybys. Binary near-Earth asteroids (NEA) (35107) 1991 VH and (175706) 1996 FG3 were selected as potential targets of the National Aeronautics and Space Administration's (NASA) dual spacecraft Janus mission. We observed 1991 VH using the 3-m NASA Infrared Telescope Facility (IRTF) on Mauna Kea, Hawaii, on July 26, 2008. 1996 FG3 was observed with the IRTF for seven nights during the spring of 2022. Compositional analysis of 1991 VH revealed that this NEA is classified as an Sq-type in the Bus-DeMeo taxonomy classification, with a composition consistent with LL ordinary chondrites. Using thermal modeling, we computed the thermally corrected spectra for 1996 FG3 and the corresponding best fit albedo of about 2-3% for the best spectra averaged for each night. Our spectral analysis indicates that this NEA is a Ch-type. The best possible meteorite analogs for 1996 FG3, based on curve matching, are two carbonaceous chondrites, Y-86789 and Murchison. No rotational variation was detected in the spectra of 1996 FG3, which means there may not be any heterogeneities on the surface of the primary. However, a clear phase reddening effect was observed in our data, confirming findings from previous ground-based studies.

astro-ph.EP↗

arXiv2022

Physical Characterization of Near-Earth Asteroid (52768) 1998 OR2: Evidence of Shock 1 Darkening/Impact Melt

We conducted photometric and spectroscopic characterization of near-Earth asteroid (52768) 1998 OR2 during a close approach to the Earth in April of 2020. Our photometric measurements confirm the rotation period of the asteroid to be 4.126 +/- 0.179 hours, consistent with the previously published value of 4.112 +/- 0.001 hours. By combining our visible spectroscopic measurements (0.45 - 0.93 microns) with archival MITHNEOS near infrared spectra (0.78 - 2.49 microns), we classify the asteroid as an Xn-type in the Bus-DeMeo taxonomy. The combined spectrum shows two weak absorption bands: Band I at 0.926 +/- 0.003 microns and Band II at 2.07 +/- 0.02 microns with band depths of 4.5 +/- 0.15% and 4.0 +/- 0.21%, respectively. The band area ratio is 1.13 +/- 0.05. These spectral band parameters plot at the tip of the S(IV) region of the Gaffey S-asteroid subtypes plot suggesting an affinity to ordinary chondrite meteorites. We calculated the chemistry of the olivine and pyroxene using the Band I center to be 20.1 +/- 2.3 mol% fayalite and 18.2 +/- 1.5 mol% ferrosilite, consistent with H chondrites. Principal component analysis of 1998 OR2's combined visible-NIR spectrum fall on the C/X-complex side of the alpha-line, near the end of the shock darkening trend, consistent with its weak absorption bands (band depth < 5%). We use an aerial mixing model with lab measurements of the shock darkened H5 chondrite, Chergach, to constrain the amount of shock darkened material on the asteroid's surface at ~63% dark lithology and ~37% light lithology.

astro-ph.EP↗

arXiv2022

Photometric Characterization and Trajectory Accuracy of Starlink Satellites: Implications for Ground-Based Astronomical Surveys

Starlink is a low-Earth orbit (LEO) satellite constellation operated by Space Exploration Technologies Corp. (SpaceX) which aims to provide global satellite internet access. Thus far, most photometric observations of Starlink satellites have primarily been from citizen scientists' visual observations without using quantitative detectors. This paper aims to characterize Starlink satellites and investigate the impact of mega constellations on ground-based astronomy, considering both the observed magnitude and two-line element (TLE) residuals. We collected 353 observations of 61 different Starlink satellites over a 16-month period and we found an average GAIA G magnitude of 5.5 +/- 0.13 with a standard deviation of 1.12. The average magnitude of V1.0 (pre-VisorSat) Starlinks was 5.1 +/- 0.13 with a standard deviation of 1.13. SpaceX briefly used a low-albedo coating on a Starlink satellite called DarkSat to test light pollution mitigation technologies. The brightness of DarkSat was found to be 7.3 +/- 0.13 with a standard deviation of 0.78, or 7.6 times fainter than V1.0 Starlinks. This concept was later abandoned due to thermal control issues and sun visors were used in future models called VisorSats. The brightness of VisorSats was found to be 6.0 +/- 0.13 with a standard deviation of 0.79, or 2.3 times fainter than V1.0 Starlinks. Over the span of the observations, we found that TLEs were accurate to within an average of 0.12 degrees in right ascension and -0.08 degrees in declination. The error is predominantly along-track, corresponding to a 0.3 second time error between the observed and TLE trajectories. Our observations show that a time difference of 0.3 +/- 0.28 seconds is viable for a proposed 10 second shutter closure time to avoid Starlinks in images.

astro-ph.EP↗

arXiv2022

Near-Infrared Spectroscopy Of The Nucleus Of Low-Activity Comet P/2016 BA$_{14}$ During Its 2016 Close Approach

The Near-Earth Comet P/2016 BA$_{14}$ (PanSTARRS) is a slow-rotatating nearly-dormant object, a likely dynamical twin of 252P/LINEAR, and was recently shown to have a mid-infrared spectrum very dissimilar to other comets. BA$_{14}$ also recently selected one of the back-up targets for the ESA's \textit{Comet Interceptor}, so a clearer understanding of BA$_{14}$'s modern properties would not just improve our understanding of how comets go dormant, but could also aid planning for a potential spacecraft visit. We present observations of BA$_{14}$ taken on two dates during its 2016 Earth close approach with the NASA Infrared Telescope Facility, both of which are consistent with direct observations of its nucleus. The reflectance spectrum of BA$_{14}$ is similar to 67P/Churyumov-Gerasimenko, albeit highly phase-reddened. Thermal emission contaminates the reflectance spectrum at longer wavelengths, which we correct with a new Markov Chain Monte Carlo thermal modeling code. The models suggest $BA_{14}$'s visible geometric albedo is $p_V=0.01-0.03$, consistent with radar observations, its beaming parameter is typical for NEOs observed in its geometry, and its reflectrance spectrum is red and linear throughout H and K band. It appears very much like a "normal" comet nucleus, despite its mid-infrared oddities. A slow loss of fine grains as the object's activity diminished might help to reconcile some of the lines of evidence, and we discuss other possibilities. A spacecraft flyby past BA$_{14}$ could get closer to the nucleus than with a more active target, and we highlight some science questions that could be addressed with a visit to a (nearly-)dormant comet.

astro-ph.EP↗