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New Kreutz Sungrazer C/2026 A1 (MAPS): Third Time's the Charm?

Zdenek Sekanina

TL;DR

This study analyzes comet C/2026 A1 (MAPS), a newly discovered Kreutz sungrazer with an exceptionally long orbital period, to understand its origin within the fragmentation history of Aristotle's comet. By comparing multiple orbital solutions, the authors constrain MAPS’ barycentric period to exceed 1000 years (potentially ~1663 years) and infer a perihelion epoch near AD 357, aligning intriguingly with Ammianus Marcellinus’ 363 sighting and supporting a broad contact-binary fragmentation scenario. They argue MAPS is an outlying, second-generation fragment from a large parent (>20 km) and likely not closely related to Pereyra, based on nodal and lineage analyses, while its preperihelion light curve shows early accelerated brightening without outbursts. The results have implications for the timing and structure of the Kreutz system’s fragmentation, providing observational support for the AD 363 swarm idea and refining the taxonomy of Kreutz populations. Overall, MAPS offers a rare testbed for the long-term dynamical evolution of sungrazers and the viability of the contact-binary hypothesis.

Abstract

This paper describes progress achieved in early investigations of the orbital motion and light curve of comet C/2026 A1 (MAPS), the third ground-based discovery of a Kreutz sungrazer in the 21st century. The highly unusual trait of the comet that has so far been ascertained is its extraordinarily long orbital period. The most recent orbital computations make it increasingly likely that the object is a fragment of one of the comets observed by Ammianus Marcellinus in AD 363, thereby strengthening evidence in support of the contact-binary hypothesis of the Kreutz system. In this context, the comet is the only second-generation fragment of Aristotle's comet that we are aware of to appear after the 12th century. It does not look like a major fragment, but rather like an outlying fragment of a much larger sungrazer. In 363 it apparently separated from a parent different from the lineage of comet Pereyra. The light curve of comet MAPS has so far been fairly smooth, without outbursts. To reach the brightness of comet Ikeya-Seki, the comet would have to follow an r^(-17) law in the coming weeks, which is unlikely.

New Kreutz Sungrazer C/2026 A1 (MAPS): Third Time's the Charm?

TL;DR

This study analyzes comet C/2026 A1 (MAPS), a newly discovered Kreutz sungrazer with an exceptionally long orbital period, to understand its origin within the fragmentation history of Aristotle's comet. By comparing multiple orbital solutions, the authors constrain MAPS’ barycentric period to exceed 1000 years (potentially ~1663 years) and infer a perihelion epoch near AD 357, aligning intriguingly with Ammianus Marcellinus’ 363 sighting and supporting a broad contact-binary fragmentation scenario. They argue MAPS is an outlying, second-generation fragment from a large parent (>20 km) and likely not closely related to Pereyra, based on nodal and lineage analyses, while its preperihelion light curve shows early accelerated brightening without outbursts. The results have implications for the timing and structure of the Kreutz system’s fragmentation, providing observational support for the AD 363 swarm idea and refining the taxonomy of Kreutz populations. Overall, MAPS offers a rare testbed for the long-term dynamical evolution of sungrazers and the viability of the contact-binary hypothesis.

Abstract

This paper describes progress achieved in early investigations of the orbital motion and light curve of comet C/2026 A1 (MAPS), the third ground-based discovery of a Kreutz sungrazer in the 21st century. The highly unusual trait of the comet that has so far been ascertained is its extraordinarily long orbital period. The most recent orbital computations make it increasingly likely that the object is a fragment of one of the comets observed by Ammianus Marcellinus in AD 363, thereby strengthening evidence in support of the contact-binary hypothesis of the Kreutz system. In this context, the comet is the only second-generation fragment of Aristotle's comet that we are aware of to appear after the 12th century. It does not look like a major fragment, but rather like an outlying fragment of a much larger sungrazer. In 363 it apparently separated from a parent different from the lineage of comet Pereyra. The light curve of comet MAPS has so far been fairly smooth, without outbursts. To reach the brightness of comet Ikeya-Seki, the comet would have to follow an r^(-17) law in the coming weeks, which is unlikely.
Paper Structure (7 sections, 4 equations, 3 figures, 2 tables)

This paper contains 7 sections, 4 equations, 3 figures, 2 tables.

Table of Contents

  1. Introduction
  2. The Orbital Elements
  3. The Orbital Period and Its Ramifications
  4. Orbital Period As a Product of Conditions At Separation
  5. Relationship to Major Kreutz Sungrazers: Preliminary Results
  6. The Light Curve
  7. Final Remarks and Conclusions

Figures (3)

  • Figure 1: A sungrazer's nucleus in close proximity of perihelion shortly before and after breaking up tidally into two uneven fragments. In Scenario I (top) it is the more sizable fragment A that begins its existence on the sunward side of the parent's nucleus (to the right). It ends up in an orbit of shorter period than the parent's. On the other hand, the smaller fragment B, on the far side from the Sun, enters an orbit of longer period than was the parent's --- the case of comet MAPS. In Scenario II, the positions of the fragments are reversed and so are their future orbital periods. The circled disks are the centers of mass of the parent comet and the two fragments. (Adapted from Sekanina & Kracht 2022.)
  • Figure 2: Preperihelion light curves of the Kreutz sungrazers discovered from the ground. Observed magnitudes were taken mostly from the Comet Observation Database (COBS), for C/1882 R1, C/1945 X1, and C/1965 S1 from other sources, as mentioned in the text. The normalized magnitude has been reduced to 1 AU from the Earth by an inverse square power law, to a zero phase angle by the Marcus law, and standardized by applying the personal/instrumental correction. Among the interesting features of the plot is that C/2024 S1, which did not survive perihelion, was mostly brighter than C/2011 W3, which did survive it (though barely), and that C/2026 A1 will be substantially fainter near perihelion than C/1965 S1 unless its rate of brightening picks up a lot between 40 and 30 days before perihelion.
  • Figure 3: Dependence of the normalized magnitude of the Kreutz sungrazers from Figure 2 on heliocentric distance before perihelion. For the sources of the data, see the caption to Figure 2 and text. Interesting features of the plot include the same $r^{-3.5}$ law that C/1882 R1 and C/1965 S1 follow, even though the data for the first object are scanty and the slope uncertain; C/2011 W3 brightened much more rapidly; C/2024 S1 was actually fading on its approach to the Sun both before and after the outburst; and for C/2026 A1 to reach the brightness of C/1965 S1, it would have to brighten according to an $r^{-17}$ law at heliocentric distances between 1.4 AU and 1 AU.