Dracula's Chivito: discovery of a large edge-on protoplanetary disk with Pan-STARRS (2402.01063v2)

Abstract: We report the serendipitous discovery of a large edge-on protoplanetary disk associated with the infrared source IRAS 23077+6707. The disk's apparent size in the Pan-STARRS (PS1) images is ~11", making this one of the largest known disks on the sky. It is likely a young system, still surrounded by the envelope which is very faint but still visible in the PS1 images in the northern part (alternatively this structure could be filaments from the disk itself). We use the PS1 magnitudes and other available photometric data to construct the spectral energy distribution (SED) of the disk. An optical spectrum indicates that the obscured star is hot, most likely late A. We adopt a distance of 300 pc for this object based on Gaia DR3 extinctions. We model the system using the HOCHUNK3D radiative transfer software and find that the system is consistent with a hot star of effective temperature 8000 K surrounded by a disk of size 1650 AU and mass 0.2 M_solar at inclination 82 degrees.

• The paper details the discovery of a large, edge-on protoplanetary disk, DraChi, using serendipitous Pan-STARRS observations.
• It employs detailed radiative transfer modeling with HOCHUNK3D to derive key parameters such as a 0.2 M☉ disk mass, 82° inclination, and a 1650 AU radius.
• The findings highlight the importance of edge-on views in revealing vertical disk structure and advancing our understanding of planet formation.

Analysis of "Dracula's Chivito": Observational and Theoretical Insights into an Edge-On Protoplanetary Disk

The paper "Dracula's Chivito: discovery of a large edge-on protoplanetary disk with Pan-STARRS" by Berghea et al. details the unexpected discovery of a significant protoplanetary disk using images from the Pan-STARRS telescope. Titled "Dracula's Chivito" (or DraChi), this disk is notable for its large apparent size and relatively high inclination. The discovery is framed within the broader context of understanding planet formation processes and disk morphology, particularly emphasizing the utility of edge-on views to paper vertical disk structures.

Observational Findings

The serendipitous discovery of DraChi occurred during an unrelated paper involving AGN candidates. The authors analyze data captured by the Pan-STARRS1 (PS1) telescope's broadband filters, utilizing them to confirm the disk's large, edge-on orientation. The PS1 images facilitated the identification of the disk's bipolar structure, and the authors note an apparent size of approximately 11 arcseconds. Such a considerable size categorizes DraChi among the largest protoplanetary disks detected to date. The analysis details potential faint envelope structures, potentially indicative of its Class I evolutionary status.

The spectrum of the central star, derived from available data, suggests a classification consistent with a hot A-type star, likely of type A9. The significant extinction observed and recorded in the optical spectrum necessitated adjustments for accurate classification, providing an estimated mass for the star between 1.5 - 2.0 M_☉.

Radiative Transfer Modeling

The paper employs detailed radiative transfer modeling using the HOCHUNK3D software suite, accommodating constraints imposed by both image morphology and spectral data. The researchers determined key system parameters and pursued model optimization to align with the spectral energy distribution (SED) constructed from photometric data across various wavelengths, including PS1 observations and archival sources such as ALLWISE and 2MASS.

The radiative transfer analysis reveals a complex disk model consistent with observational data, suggesting a 0.2 M_☉ disk mass, a significant inclination angle of 82 degrees, and a maximum radius extending approximately 1650 astronomical units from the star. The modeling underscores the potential presence of a dissipating envelope, reinforcing the disk's transitional nature between Class I and II phases. Such data provide invaluable insights into the extent of dust settling, disk flaring, and the overarching morphological characteristics of protoplanetary systems.

Implications and Future Developments

Berghea et al.'s analysis affirms the value of edge-on protoplanetary disks in elucidating vertical dust and gas distribution—a critical factor in understanding disc dynamics and potential planetesimal formation. Furthermore, the paper advocates for the continued cataloging and characterization of such systems, acknowledging the likelihood of additional undetected edge-on disks in observational archives.

The narrative of DraChi emphasizes the power of both observational serendipity and strategic modeling to extend our understanding of disk structures. As noted, the implications for planet formation theories are pronounced, and future research should consider high-resolution observations at longer wavelengths to further discern grain size distributions and refine these mass estimates. Additionally, the findings argue for the potential of edge-on systems to reveal phenomena potentially occluded in more inclined disks, thereby offering fresh perspective on disk evolution and dissipative processes.

Overall, the discovery and comprehensive characterization of DraChi accentuate ongoing efforts to decode the mechanisms underpinning protoplanetary environments, offering indispensable context to ongoing discussions on planetary system diversity observed within our galaxy. Such studies are crucial to revealing the underpinnings of planet formation, reinforcing the advantages afforded by a multi-wavelength and multi-dimensional approach to disk analysis.