ALMA’s Sharpest View of IRAS 08544–4431: Unveiling the Dust Distribution Asymmetries in the Circumbinary Disk
9 affiliations
- 1Macquarie University
- 2INAF
- 3ATNF
- 4Institute of Astronomy
- 5Monash University
- 6Univ. Grenoble Alpes
- 7Institut de Radioastronomie Millimétrique
- 8Observatorio Astronómico Nacional (OAN-IGN)
- 9Villanova University
Abstract
The interactions between post–asymptotic giant branch (post-AGB) binaries and their circumbinary disks play a central role in shaping the evolution of these systems. Circumbinary disks around post-AGB binaries are stable, though relatively short-lived, structures (10 ⁴ −10 ⁵ yr), and their physical properties and evolution remain poorly understood. In this study, we target IRAS 08544−4431, one of the best-studied post-AGB binaries. This system has well-constrained stellar and orbital parameters, exhibits well-defined characteristic refractory-depleted photospheric chemistry, and hosts a stable, sub-Keplerian circumbinary disk extending from a well-resolved sublimation rim at approximately 8 au to outer radii of approximately 1000 au. We probe the disk layers close to the midplane using Atacama Large Millimeter/submillimeter Array (ALMA) Band 7 continuum and ¹² CO J = 3−2 observations of IRAS 08544−4431 obtained with baselines up to 16.2 km. These data provide the finest angular resolution as yet achieved with ALMA for dust-continuum observations of post-AGB binaries with an (almost) face-on disk (15 au; 10 mas). The resulting map of dust continuum enabled resolving disk inner rim, a largely smooth radial profile, and a prominent azimuthal asymmetry at a radius of ∼45 mas. Notably, the location of this dust asymmetry coincides with the forward-scattering peak reported in SPHERE/VLT observations of IRAS 08544−4431. The ¹² CO emission is more extended than the dust continuum and confirms the disk rotation in this system. However, the global ¹² CO map shows indications of a spatial offset from the dust asymmetry, suggesting some degree of gas–dust decoupling. Together, these observations establish IRAS 08544−4431 as a key laboratory for studying disk and dust evolution in a parameter space distinct from that of young stars with protoplanetary disks.
Related
- The ALMA-QUARKS survey: A Keplerian Circumbinary Disk Candidate in the High-mass Star-forming Region IRAS 08303-4303
- Binary tidal evolution as a sculptor of circumbinary planet architectures
- Circumbinary discs as the origin of circumstellar material around interacting H-poor supernovae and fast blue optical transients
- Pulsed Accretion onto Eccentric Binaries in Highly Misaligned Circumbinary Disks
- Pulsed Accretion onto Eccentric Binaries in Highly Misaligned Circumbinary Disks
BibTeX
@article{mohorian2026almas,
title = {{ALMA’s Sharpest View of IRAS 08544–4431: Unveiling the Dust Distribution Asymmetries in the Circumbinary Disk}},
author = {Maksym Mohorian and Devika Kamath and Elizabeth Cappellazzo and Kateryna Andrych and Jacques Kluska and Hans Van Winckel and Daniel Price and Toon De Prins and Arancha Castro-Carrizo and Javier Alcolea and Nicolás Cuello and Matthias Fabry and Valentin Bujarrabal},
journal = {The Astrophysical Journal},
year = {2026},
month = oct,
doi = {10.3847/1538-4357/aeac1d},
url = {https://iopscience.iop.org/article/10.3847/1538-4357/aeac1d},
note = {CC BY 4.0},
}
RIS
TY - JOUR
TI - ALMA’s Sharpest View of IRAS 08544–4431: Unveiling the Dust Distribution Asymmetries in the Circumbinary Disk
AU - Maksym Mohorian
AU - Devika Kamath
AU - Elizabeth Cappellazzo
AU - Kateryna Andrych
AU - Jacques Kluska
AU - Hans Van Winckel
AU - Daniel Price
AU - Toon De Prins
AU - Arancha Castro-Carrizo
AU - Javier Alcolea
AU - Nicolás Cuello
AU - Matthias Fabry
AU - Valentin Bujarrabal
PY - 2026
DA - 2026/10/19
JO - The Astrophysical Journal
DO - 10.3847/1538-4357/aeac1d
UR - https://iopscience.iop.org/article/10.3847/1538-4357/aeac1d
AB - The interactions between post–asymptotic giant branch (post-AGB) binaries and their circumbinary disks play a central role in shaping the evolution of these systems. Circumbinary disks around post-AGB binaries are stable, though relatively short-lived, structures (10 ⁴ −10 ⁵ yr), and their physical properties and evolution remain poorly understood. In this study, we target IRAS 08544−4431, one of the best-studied post-AGB binaries. This system has well-constrained stellar and orbital parameters, exhibits well-defined characteristic refractory-depleted photospheric chemistry, and hosts a stable, sub-Keplerian circumbinary disk extending from a well-resolved sublimation rim at approximately 8 au to outer radii of approximately 1000 au. We probe the disk layers close to the midplane using Atacama Large Millimeter/submillimeter Array (ALMA) Band 7 continuum and ¹² CO J = 3−2 observations of IRAS 08544−4431 obtained with baselines up to 16.2 km. These data provide the finest angular resolution as yet achieved with ALMA for dust-continuum observations of post-AGB binaries with an (almost) face-on disk (15 au; 10 mas). The resulting map of dust continuum enabled resolving disk inner rim, a largely smooth radial profile, and a prominent azimuthal asymmetry at a radius of ∼45 mas. Notably, the location of this dust asymmetry coincides with the forward-scattering peak reported in SPHERE/VLT observations of IRAS 08544−4431. The ¹² CO emission is more extended than the dust continuum and confirms the disk rotation in this system. However, the global ¹² CO map shows indications of a spatial offset from the dust asymmetry, suggesting some degree of gas–dust decoupling. Together, these observations establish IRAS 08544−4431 as a key laboratory for studying disk and dust evolution in a parameter space distinct from that of young stars with protoplanetary disks.
SN - 0004-637X
SN - 1538-4357
ER -