Conspicuous Gas, Cryptic Dust: Spectroscopy and Chromaticity of Complex Periodic Variables
Abstract
Complex periodic variables (CPVs) are young low-mass stars whose light curves show periodic dips indicative of transiting corotating material. The origin and composition of this material are unclear. Here we present new optical and near-infrared spectroscopy and photometry of four CPVs from Magellan, Keck, Hale, MuSCAT1, MuSCAT2, Tierras, KeplerCam, and TESS. The spectra imply that CPVs host magnetically bound circumstellar plasma clumps, on the basis of sinusoidal-in-time Balmer emission out of transit, and Balmer dimming during transit. Yet large night-to-night changes in circumstellar hydrogen emissivity occur without clear changes in light curve morphology, suggesting that the sharp flux dips are caused not by circumstellar plasma but by dust. Optical chromaticities (depth proportional to λ−β, with β = 0.79 ± 0.16) support this, but the power law breaks in the near-infrared, where a single power law under-predicts the depths observed at 2.1 microns. We therefore favor dips caused by dusty plasma clumps with opaque cores and optically thin halos, though we cannot rule out models in which the dust properties vary per-star or per-epoch. Observations at wavelengths greater than 2 microns and less than 0.4 microns would test this interpretation and clarify the dust's origin.
Related
- Photometric eclipse-center variations over the long cycles of Magellanic double-periodic variables
- 1000 cataclysmic variables identified from DESI spectroscopy
- Infrared spectroscopy of the longest-period Galactic Mira variables from Palomar Gattini-IR: Identification of a candidate thermally pulsing Super-Asymptotic Giant Branch star
- Quantifying Sky Map Resolution Requirements for Beam Chromaticity Correction in Sky-Averaged 21 cm Experiments
- A catalog of Gaia DR3 luminous blue variables and candidate luminous blue variables. Limits of Gaia DR3 light curves for identifying luminous blue variables
BibTeX
@misc{bouma2026conspicuous,
title = {{Conspicuous Gas, Cryptic Dust: Spectroscopy and Chromaticity of Complex Periodic Variables}},
author = {Luke G. Bouma and Facundo Perez Paolino and Lynne A. Hillenbrand and Juliana Garcia-Mejia and Allyson Bieryla and Patrick Tamburo and David Charbonneau and John H. Livingston and Keisuke Isogai and Norio Narita and Akihiko Fukui and Enric Palle and Felipe Murgas and Adolfo S. Carvalho and Howard Isaacson and Jessica J. Spake and Luisa M. Rebull and Moira M. Jardine and David R. Ciardi and Jeff A. Valenti},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2609.00136},
eprint = {2609.00136},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2609.00136},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Conspicuous Gas, Cryptic Dust: Spectroscopy and Chromaticity of Complex Periodic Variables
AU - Luke G. Bouma
AU - Facundo Perez Paolino
AU - Lynne A. Hillenbrand
AU - Juliana Garcia-Mejia
AU - Allyson Bieryla
AU - Patrick Tamburo
AU - David Charbonneau
AU - John H. Livingston
AU - Keisuke Isogai
AU - Norio Narita
AU - Akihiko Fukui
AU - Enric Palle
AU - Felipe Murgas
AU - Adolfo S. Carvalho
AU - Howard Isaacson
AU - Jessica J. Spake
AU - Luisa M. Rebull
AU - Moira M. Jardine
AU - David R. Ciardi
AU - Jeff A. Valenti
PY - 2026
DA - 2026/09/01
PB - arXiv
DO - 10.48550/arxiv.2609.00136
UR - https://arxiv.org/abs/2609.00136
AB - Complex periodic variables (CPVs) are young low-mass stars whose light curves show periodic dips indicative of transiting corotating material. The origin and composition of this material are unclear. Here we present new optical and near-infrared spectroscopy and photometry of four CPVs from Magellan, Keck, Hale, MuSCAT1, MuSCAT2, Tierras, KeplerCam, and TESS. The spectra imply that CPVs host magnetically bound circumstellar plasma clumps, on the basis of sinusoidal-in-time Balmer emission out of transit, and Balmer dimming during transit. Yet large night-to-night changes in circumstellar hydrogen emissivity occur without clear changes in light curve morphology, suggesting that the sharp flux dips are caused not by circumstellar plasma but by dust. Optical chromaticities (depth proportional to λ^−β, with β = 0.79 ± 0.16) support this, but the power law breaks in the near-infrared, where a single power law under-predicts the depths observed at 2.1 microns. We therefore favor dips caused by dusty plasma clumps with opaque cores and optically thin halos, though we cannot rule out models in which the dust properties vary per-star or per-epoch. Observations at wavelengths greater than 2 microns and less than 0.4 microns would test this interpretation and clarify the dust's origin.
ER -