The moth: an unusual circumstellar structure associated with HD 61005


We present the discovery of an unusual spatially resolved circumstellar structure associated with the approximate to 90 Myr, nearby, G dwarf star HD 61005. Observations from the FEPS Spitzer Legacy Science survey reveal thermal emission in excess of expected stellar photospheric levels. Follow-up 0.1 '' resolution HST NICMOS coronagraphic images reveal scattered starlight <= 7 '' (similar to 240 AU) from the occulted star (1.1 mu m flux density = 18 +/- 3.3 mJy; and 0.77%+/- 0.16% starlight). The extremely high near-IR scattering fraction and IR excess luminosity f=L-IR/L-* approximate to 2x10(-3) suggests scattering particle sizes of order a <= 1.1 mu m/2 pi similar to 0.2 mu m comparable to the blowout size (a approximate to 0.3 mu m) due to radiation a pressure from the star. Dust-scattered starlight is traced inward to an instrumental limit of similar to 10 AU. The structure exhibits a strong asymmetry about its morphological major axis but is mirror-symmetric about its minor axis.

circumstellar matter, infrared : stars, planetary systems : protoplanetary disks, stars : individual (HD 61005), SOLAR-TYPE STARS, SUN-LIKE STARS, PLANETARY SYSTEMS FEPS, DEBRIS DISKS, INTERSTELLAR-MEDIUM, YOUNG STARS, EVOLUTION, DUST, DISCOVERY, SPITZER, Astronomy & Astrophysics
Hines, D., et al. (2007): The Moth: An Unusual Circumstellar Structure Associated with HD 61005. The Astronomical Journal, 671(2). DOI: