Now you see me, now you don't: Deep, long-lived obscuration events of white dwarfs by dust and debris from disintegrating planetesimals

@misc{roestel2026dont,
  title = {{Now you see me, now you don't: Deep, long-lived obscuration events of white dwarfs by dust and debris from disintegrating planetesimals}},
  author = {J. van Roestel and S. Bhattacharjee and J. A. Guidry and I. Caiazzo and T. Cunningham and J. J. Hermes and S. Torres and Z. Vanderbosch and A. J. Drake and M. Hollands and B. T. Gänsicke and K. De and T. Prince and A. C. Rodriguez and L. B. Ould Rouis and A. A. Mahabal and E. C. Bellm and M. W. Coughlin and M. J. Graham and D. Hale and G. Helou and J. C. Jaimes and M. Kasliwal and R. R. Laher and R. L. Reed},
  howpublished = {arXiv},
  year = {2026},
  month = sep,
  doi = {10.48550/arxiv.2609.08923},
  eprint = {2609.08923},
  archivePrefix = {arXiv},
  url = {https://arxiv.org/abs/2609.08923},
  note = {CC BY 4.0},
}

TY  - UNPB
TI  - Now you see me, now you don't: Deep, long-lived obscuration events of white dwarfs by dust and debris from disintegrating planetesimals
AU  - J. van Roestel
AU  - S. Bhattacharjee
AU  - J. A. Guidry
AU  - I. Caiazzo
AU  - T. Cunningham
AU  - J. J. Hermes
AU  - S. Torres
AU  - Z. Vanderbosch
AU  - A. J. Drake
AU  - M. Hollands
AU  - B. T. Gänsicke
AU  - K. De
AU  - T. Prince
AU  - A. C. Rodriguez
AU  - L. B. Ould Rouis
AU  - A. A. Mahabal
AU  - E. C. Bellm
AU  - M. W. Coughlin
AU  - M. J. Graham
AU  - D. Hale
AU  - G. Helou
AU  - J. C. Jaimes
AU  - M. Kasliwal
AU  - R. R. Laher
AU  - R. L. Reed
PY  - 2026
DA  - 2026/09/08
PB  - arXiv
DO  - 10.48550/arxiv.2609.08923
UR  - https://arxiv.org/abs/2609.08923
AB  - Transiting dust and debris around white dwarfs provide a direct view of planetary disruption. We report six previously non-variable white dwarfs that underwent single, deep obscuration events, including ZTF~J2327+0019, which fully disappeared for more than a year. These discoveries raise the number of confirmed debris-transit white dwarfs to 20. In addition, the systematic search of negative alerts from the Zwicky Transient Facility (ZTF), followed by photometric and spectroscopic observations, also identified three hot (T≈ 55000--$92000$ K) irregular variables as candidate debris hosts. The six confirmed events last weeks to years, reach transit depths of 25--100%, and show no recurrence over the 8-yr ZTF baseline. They are therefore much deeper and longer lived than the recurring, minute-scale transits typical of previously known systems. The observed reddening is consistent with dust extinction, and high-speed photometry reveals minute-scale structure in several systems, indicating rapidly moving material close to the white dwarf. ZTF~J2327+0019 also shows a simultaneous WISE infrared brightening, the first observed coincidence of infrared brightening and optical obscuration in a white dwarf. Two of the six hosts, one DAZ and one DBZ, are strongly metal enriched, with accretion rates among the highest known for their spectral types and minimum accreted masses of 3.5× 10^19 and 2× 10^24 g. We interpret the one-off transit events as collisions between planetesimal remnants and pre-existing circumstellar debris that trigger collisional cascades: short-timescale variability traces dust-producing fragments crossing the star, while slower changes trace the build-up and clearing of an optically thick dusty structure. In contrast, ZTF~J0436+5728 shows a coherent 5.910-h period, consistent with a rocky body shedding material near the tidal-disruption radius.
ER  -