“To explain the presence of ices at high disk altitudes, we propose two possible scenarios: a disk wind that entrains sufficient amounts of dust, thus blocking part of the stellar UV radiation, or vertical mixing that cycles enough ices into the upper disk layers to balance ice photodesorption.”
HH 48 NE is a protostar located in the Chamaeleon I star-forming region, approximately 600 light-years from Earth.
It is part of a binary system with HH 48 SW, separated by a projected distance of 425 astronomical units (AU). The protoplanetary disk around HH 48 NE is of particular interest due to its nearly edge-on orientation, making it an excellent target for studying disk structure and composition.
Key characteristics of the HH 48 NE protoplanetary disk include:
Geometry:
- The disk is viewed nearly edge-on, with a lower limit inclination of 68°[1].
- It appears asymmetric in scattered light observations[1].
- A relatively large cavity (~50 AU in radius) is present, which explains the strong mid-infrared emission.
Dust properties:
- 90% of the dust mass is settled to the disk midplane, which is less than in average disks.
- The atmospheric layers contain exclusively large grains (0.3–10 µm), with small grains absent.
- There is a sharp cutoff in millimeter continuum emission.
Structure:
- The disk’s bipolar jet is tilted 6° with respect to the polar axis of the disk mid-plane.
- The gas disk appears distorted, possibly due to interaction with the companion star’s disk.
Ice composition:
- The disk is a target of the James Webb Space Telescope (JWST) Early Release program “Ice Age” to study its icy chemistry.
- Modeling suggests that the global abundance of main ice carriers (H2O, CO, CO2, NH3, CH4, and CH3OH) can be determined within a factor of 3, considering uncertainties in physical parameters.
- Ice features can be saturated at an optical depth of ≲1 due to local saturation.
Observational challenges:
- Spatial information for ice features at wavelengths >7 µm may be lost due to decreasing angular resolution at longer wavelengths with JWST.
- Radiative transfer effects complicate the direct relation between observed ice optical depths and column densities.
Stellar properties:
- The spectral type of the combined binary system is reported as K7, consistent with an effective temperature of 4000 K.
- Local visual extinction (Av) in the region is estimated to be ~3 mag.
Understanding the structure and composition of the HH 48 NE disk is crucial for studying ice chemistry in protoplanetary disks and serves as a stepping stone for analyzing other edge-on sources to be observed with JWST. The unique edge-on orientation allows for constraining disk properties that are difficult to determine in other orientations, making it an important target for advancing our understanding of protoplanetary disk evolution and planet formation processes.
References:
A JWST/MIRI analysis of the ice distribution and PAH emission in the protoplanetary disk HH 48 NE
J. A. Sturm, M. K. McClure, D. Harsono, J. B. Bergner, E. Dartois, A. C. A. Boogert, M. A. Cordiner, M. N. Drozdovskaya, S. Ioppolo, C. J. Law, D. C. Lis, B. A. McGuire, G. J. Melnick, J. A. Noble, K. I. Öberg, M. E. Palumbo, Y. J. Pendleton, G. Perotti, W. R. M. Rocha, R. G. Urso, E. F. van Dishoeck
https://arxiv.org/abs/2407.09627
The edge-on protoplanetary disk HH 48 NE I. Modeling the geometry and stellar parameters
J.A. Sturm, M.K. McClure, C.J. Law, D. Harsono, J.B. Bergner, E. Dartois, M.N. Drozdovskaya, S. Ioppolo, K.I. Öberg, M.E. Palumbo, Y.J. Pendleton, W.R.M. Rocha, H. Terada, R.G. Urso
https://arxiv.org/abs/2305.02338
See as well:
| Issue | A&AVolume 677, September 2023 |
|---|---|
| Article Number | A17 |
| Number of page(s) | 15 |
| Section | Interstellar and circumstellar matter |
| DOI | https://doi.org/10.1051/0004-6361/202346052 |
| Published online | 28 August 2023 |
The edge-on protoplanetary disk HH 48 NE II. Modeling ices and silicates
J. A. Sturm, M. K. McClure, J. B. Bergner, D. Harsono, E. Dartois, M. N. Drozdovskaya, S. Ioppolo, K. I. Öberg, C. J. Law, M. E. Palumbo, Y. J. Pendleton, W. R. M. Rocha, H. Terada and R. G. Urso
| Issue | A&AVolume 677, September 2023 |
|---|---|
| Article Number | A18 |
| Number of page(s) | 18 |
| Section | Interstellar and circumstellar matter |
| DOI | https://doi.org/10.1051/0004-6361/202346053 |
| Published online | 28 August 2023 |
https://www.aanda.org/articles/aa/full_html/2023/09/aa46053-23/aa46053-23.html
Circular Astronomy 