Searcharxiv⌕ Search
Home/Archive/arXiv

arXiv · 2605.04717

Activity and composition of periodic comets 67P/Churyumov-Gerasimenko and 103P/Hartley 2 at two different perihelion passages

E. Hemmen·M. Vander Donckt·E. Jehin·S. Hmiddouch·K. Aravind·J. Manfroid·Z. Benkhaldoun·A. Jabiri·S. Ganesh
View original source ↗Read source document ↗Export metadata ↓

Abstract

Through photometry and spectroscopy, we studied the evolution of the activity and chemical composition of comet 67P during its 2025 and 2021 perihelion passages and of comet 103P during its 2010 and 2023 passages. For each comet, we aim to compare their behavior from one apparition to another. We used the TRAPPIST telescopes to monitor the comets using broadband and narrowband filters. From the broadband images, we produced light curves and computed color indices for each passage, and we derived the activity slopes. We used a Haser model to compute the production rates of five gaseous species (CN, C2, C3, OH, and NH) and derived the proxy parameter Afrho for dust activity. We also observed both comets in spectroscopy during their most recent apparition using the Himalayan Chandra Telescope and compared the spectroscopic data to our results obtained through photometry. For both comets, our analysis of coma colors does not reveal any significant change from one passage to the other, indicating that the properties of the released dust grains are similar. Our values of the color indices are consistent with the mean values for Jupiter-family comets. We measured a slight increase in the gas and dust activities of comet 67P between 2015 and 2021, probably due to the small change in the comet's orbit that led the perihelion distance to decrease from 1.24 au for the first apparition to 1.21 au for the second one. Regarding 103P, we unambiguously measured a decrease (of at least 50\%) in the gas and dust activities between 2010 and 2023, showing a different behavior for this young, active comet. We find a typical chemical composition for both comets and detect no variation of the C2-to-CN production rate ratios and dust-to-gas ratios from one passage to the other, indicating constant compositions, even if the level of activity has changed for 103P.

Explore related subjects

astro-ph.EP

Keep this discovery

BibTeXRIS

E. Hemmen, M. Vander Donckt, E. Jehin, S. Hmiddouch, K. Aravind, J. Manfroid, Z. Benkhaldoun, A. Jabiri, S. Ganesh. 2026-05-06. Activity and composition of periodic comets 67P/Churyumov-Gerasimenko and 103P/Hartley 2 at two different perihelion passages. https://arxiv.org/abs/2605.04717

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related papers

arXiv2026

Planetary Accretion Is Less Frequent in Wide Binaries: Evidence from Metal-Enriched White Dwarfs in DESI DR1

Binary stars are common in the Galaxy, and understanding how stellar binarity influences the formation and evolution of planetary systems is an active area of research. In this study, we use metal-enriched white dwarfs in wide binaries as tracers of long-lived planetary systems. With Data Release 1 from the Dark Energy Spectroscopic Instrument (DESI), we find that the fraction of cool metal-enriched white dwarfs in wide binaries is 9.8\,$\pm$\,2.1\%, significantly lower (4.7\,$\sigma$) than the 20.5\,$\pm$\,0.9\% in a control sample of single systems. Furthermore, we identify a tentative dependence of metal enrichment on projected separation and white dwarf effective temperature, where enrichment fraction decreases at smaller separations and lower temperatures. These findings indicate that, compared to single stars, binary systems either start with smaller initial planetary reservoirs due to suppressed planetesimal formation or undergo more rapid depletion of planetary material during the initial part of the white dwarf stage.

astro-ph.EP↗
arXiv2026

The Mysterious Inspiral of WASP-12b: Why Obliquity Tides Cannot Drive Orbital Decay

WASP-12b's orbit is decaying, for unknown reasons. The planet's period is shrinking more rapidly than can be attributed to equilibrium tides or dynamical tides in a main-sequence star. Planetary obliquity tides could be sufficiently dissipative to drive WASP-12b's inspiral, but would also damp the planet's obliquity, halting the decay. Millholland & Laughlin proposed that a nearby, low-mass planet ($\sim 10$ M$_\oplus$) is maintaining a large obliquity for WASP-12b, sustaining the dissipation. We re-evaluated this hypothesis, finding that the companion must be more massive than originally proposed ($\gtrsim 65$ M$_\oplus$) to absorb WASP-12b's orbital angular momentum. Radial velocity data allowed us to rule out a companion of this type. Any companions within $3$ AU have $K \lesssim 14$ m/s at $95$% confidence.

astro-ph.EP↗
arXiv2026

Lava Tube Exploration with LunarLeaper

Lunar pits, some of which are interpreted as collapse features into underlying lava tubes, expose otherwise inaccessible stratigraphy and may provide entry points to subsurface voids that preserve records of lunar volcanism and offer potential sites for future human exploration. We synthesize the current state of knowledge on lunar pits and lava tubes, covering their morphological characteristics, classification, proposed formation mechanisms, mechanical stability, and detection from orbit. We then review the open science questions that pit and pit-wall investigation is uniquely placed to address, spanning the volcanic stratigraphy of the lunar maria, the structure and lateral variability of the regolith, and the dimensions and accessibility of subsurface conduits. To evaluate how these questions can be tackled in situ, we assess the feasibility and expected performance of geophysical and remote-sensing investigations for subsurface voids and surface exposures, mainly focusing on gravity measurements, ground-penetrating radar, high-resolution imaging, and spectroscopy. Building on this, we present LunarLeaper, a small legged robot mission concept combining a gravimeter, ground-penetrating radar, high-resolution imager, spectrometer, and leg-based geomechanical experiments to deliver the first in situ investigation of a mare pit. The concept targets the Marius Hills Pit and its associated rille, with a mobility architecture optimized for the rugged terrain encountered at pit edges and funnel slopes.

astro-ph.EP↗