ALMA Detection of Extended Millimeter Halos in the HD 32297 and HD 61005 Debris Disks
Abstract
We present Atacama Large Millimeter/submillimeter Array (ALMA) 1.3 mm (230 GHz) observations of the HD 32297 and HD 61005 debris disks, two of the most iconic debris disks because of their dramatic swept-back wings seen in scattered light images. These observations achieve sensitivities of 14 and 13 μJy beam-1 for HD 32297 and HD 61005, respectively, and provide the highest resolution images of these two systems at millimeter wavelengths to date. By adopting a Markov Chain Monte Carlo modeling approach, we determine that both disks are best described by a two-component model consisting of a broad (ΔR/R > 0.4) planetesimal belt with a rising surface density gradient and a steeply falling outer halo aligned with the scattered light disk. The inner and outer edges of the planetesimal belt are located at 78.5 ± 8.1 au and 122 ± 3 au for HD 32297, and 41.9 ± 0.9 au and 67.0 ± 0.5 au for HD 61005. The halos extend to 440 ± 32 au and 188 ± 8 au, respectively. We also detect 12CO J = 2-1 gas emission from HD 32297 co-located with the dust continuum. These new ALMA images provide observational evidence that larger, millimeter-sized grains may also populate the extended halos of these two disks previously thought to only be composed of small, micron-sized grains. We discuss the implications of these results for potential shaping and sculpting mechanisms of asymmetric debris disks.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- December 2018
- DOI:
- 10.3847/1538-4357/aaec71
- arXiv:
- arXiv:1812.05610
- Bibcode:
- 2018ApJ...869...75M
- Keywords:
-
- circumstellar matter;
- stars: individual: HD 32297;
- HD 61005;
- submillimeter: planetary systems;
- Astrophysics - Earth and Planetary Astrophysics;
- Astrophysics - Astrophysics of Galaxies;
- Astrophysics - Solar and Stellar Astrophysics
- E-Print:
- 17 pages, 5 figures, published in ApJ