page_title: IRAS 08544−4431
section_title: Dusty disc
hierarchical_section_title: IRAS 08544−4431 / Dusty disc
caption_attribution_description: English: Circumstellar disk around binary star V390 Velorum (IRAS 08544)
context_page_description: IRAS 08544−4431 is a binary system surrounded by a dusty ring in the constellation of Vela. The system contains an RV Tauri variable star and a more massive but much less luminous companion.
context_section_description: The warm material surrounding IRAS 08544−4431 has been resolved using interferometry with the AMBER and MIDI instruments at the Very Large Telescope. It is a circumbinary disc surrounding both stars, is heated mainly by the primary post-AGB star, and has a total mass of 0.015 M☉. The disc starts 9 AU from the stars and is approximately 4 AU thick at its inner edge. The thick disc protects much of the dust from direct heating out to 70 AU from the stars. Beyond 70 AU, the disc is thick enough to receive direct radiation from the stars.
  The disc is at a temperature of 1,150 K. Although the companion is far less luminous than the primary, it is brighter than expected, especially at infrared wavelengths. It is suspected to be a main sequence star with its own compact accretion disc. The best images of the disc and stars, taken using the PIONIER interferometer, show the primary star to be 0.5 mas across, the secondary to be an unresolved point source 0.91 mas away, and the circumbinary disc to be 14.15 mas in diameter. The disc is oriented at 19° to the plane of the sky aligned at an angle of about 6° away from N-S.
caption: The disc around IRAS 08544−4431 at 2μm and 10μm. Although the image resembles a doughnut lit from the front, the brightest arc is the inner wall of the far side of the disc, lit by the stars at the centre.
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