The dusty environment of HD 97300 as seen by Herschel and Spitzer

TL;DR

This study uses Herschel and Spitzer infrared imaging to analyze the dust environment around the star HD 97300, revealing a PAH-rich ring structure heated by the star, consistent with a bubble model.

Contribution

First detailed infrared imaging analysis of HD 97300's environment across multiple wavelengths, confirming the bubble structure and dust properties around the star.

Findings

The star has no infrared excess below 24 um, indicating it is on the zero-age main sequence.

The ring's morphology is consistent across 3.6 to 24 um, dominated by PAH emission.

Dust temperature around 26 K decreases with distance from the ring.

Abstract

Aims. We analyze the surroundings of HD 97300, one of two intermediate-mass stars in the Chamaeleon I star-forming region. The star is known to be surrounded by a conspicuous ring of polycyclic aromatic hydrocarbons (PAHs). Methods. We present infrared images taken with Herschel and Spitzer using 11 different broad-band filters between 3.6 um and 500 um. We compare the morphology of the emission using cuts along different position angles. We construct spectral energy distributions, which we compare to different dust models, and calculate dust temperatures. We also derive opacity maps and analyze the density structure of the environment of HD 97300. Results. We find that HD 97300 has no infrared excess at or below 24 um, confirming its zero-age main-sequence nature. The morphology of the ring is very similar between 3.6 um and 24 um. The emission at these wavelengths is dominated by either PAH features or PAH continuum. At longer wavelengths, only the northwestern part of the ring is visible. A fit to the 100-500 um observations suggests that the emission is due to relatively warm (~26 K) dust. The temperature gradually decreases with increasing distance from the ring. We find a general decrease in the density from north to south, and an approximate 10% density increase in the northeastern part of the ring. Conclusions. Our results are consistent with the theory that the ring around HD 97300 is essentially a bubble blown into the surrounding interstellar matter and heated by the star.