3 Search Results

In this work, we present the first polarimetric detection of the inner disk component around the pre-main-sequence B9.5 star HD 141569A. Gemini Planet Imager H-band (1.65 μm) polarimetric differential imaging reveals the highest signal-to-noise ratio detection of this ring yet attained and traces structure inward to 0farcs25 (28 au at a distance of 111 pc). The radial polarized intensity image shows the east side of the disk, peaking in intensity at 0farcs40 (44 au) and extending out to 0farcs9 (100 au). There is a spiral arm–like enhancement to the south, reminiscent of the known spiral structures on the outer ringsmore » of the disk. The location of the spiral arm is coincident with ¹²CO J = 3–2 emission detected by ALMA and hints at a dynamically active inner circumstellar region. Our observations also show a portion of the middle dusty ring at ~220 au known from previous observations of this system. We fit the polarized H-band emission with a continuum radiative transfer Mie model. Our best-fit model favors an optically thin disk with a minimum dust grain size close to the blowout size for this system, evidence of ongoing dust production in the inner reaches of the disk. The thermal emission from this model accounts for virtually all of the far-infrared and millimeter flux from the entire HD 141569A disk, in agreement with the lack of ALMA continuum and CO emission beyond ~100 au. A remaining 8–30 μm thermal excess a factor of ~2 above our model argues for an as-yet-unresolved warm innermost 5–15 au component of the disk.« less

We have obtained Hubble Space Telescope STIS and NICMOS and Gemini/GPI scattered-light images of the HD 191089 debris disk. We identify two spatial components: a ring resembling the Kuiper Belt in radial extent (FWHM ~ 25 au, centered at ~46 au) and a halo extending to ~640 au. We find that the halo is significantly bluer than the ring, consistent with the scenario that the ring serves as the "birth ring" for the smaller dust in the halo. We measure the scattering phase functions in the 30°–150° scattering-angle range and find that the halo dust is more forward- and backward-scatteringmore » than the ring dust. We measure a surface density power-law index of -0.68 ± 0.04 for the halo, which indicates the slowdown of the radial outward motion of the dust. Using radiative transfer modeling, we attempt to simultaneously reproduce the (visible) total and (near-infrared) polarized intensity images of the birth ring. Our modeling leads to mutually inconsistent results, indicating that more complex models, such as the inclusion of more realistic aggregate particles, are needed.« less

In this work, we present new high resolution imaging of a light-scattering dust ring and halo around the young star HD 35841. Using spectroscopic and polarimetric data from the Gemini Planet Imager in H-band (1.6 μm), we detect the highly inclined (i = 85°) ring of debris down to a projected separation of ~12 au (~0farcs12) for the first time. Optical imaging from HST/STIS shows a smooth dust halo extending outward from the ring to >140 au (>1farcs4). We measure the ring's scattering phase function and polarization fraction over scattering angles of 22°–125°, showing a preference for forward scattering andmore » a polarization fraction that peaks at ~30% near the ansae. Modeling of the scattered-light disk indicates that the ring spans radii of ~60–220 au, has a vertical thickness similar to that of other resolved dust rings, and contains grains as small as 1.5 μm in diameter. These models also suggest the grains have a low porosity, are more likely to consist of carbon than astrosilicates, and contain significant water ice. The halo has a surface brightness profile consistent with that expected from grains pushed by radiation pressure from the main ring onto highly eccentric but still bound orbits. We also briefly investigate arrangements of a possible inner disk component implied by our spectral energy distribution models, and speculate about the limitations of Mie theory for doing detailed analyses of debris disk dust populations.« less