Warm dusty discs: Exploring the A star 24um debris population

Abstract

(Abridged) Studies of debris discs have shown that most systems are analogous to the EKB. In this study we aim to determine how many IRAS 25um excesses towards A stars are real, and investigate where the dust lies. We observe with TIMMI2, VISIR, Michelle and TReCS a sample of A and B-type main sequence stars reported as having mid-IR excess. We constrain the location of the debris through combined modelling of the emission spectrum and a modelling technique designed to constrain the radial extent of emission in mid-IR imaging. We independently confirm the presence of warm dust around 3 of the candidates: HD3003, HD80950 and eta Tel. For the binary HD3003 a stability analysis indicates the dust is either circumstellar and lying at ~4 AU with the binary orbiting at >14AU, or the dust lies in an unstable location; there is some evidence for temporal evolution of its excess emission on a ~20 year timescale. For 7 of the targets we present quantitative limits on the location of dust around the star. We demonstrate that the disc around HD71155 must have spatially distinct components at 2 and 60AU. We model the limits of current instrumentation and show that most of the known A star debris discs which could be readily resolved at 18um on 8m instruments have been resolved. Limits from unresolved imaging can help distinguish between competing models of the disc emission, but resolved imaging is key to the determination of the disc location. Modelling of the detection limits for extended emission can be useful for targeting future observational campaigns. MIRI on the JWST will be able to resolve most of the known A star debris disc population. METIS on the E-ELT will provide the opportunity to explore the hot disc population more thoroughly by detecting extended emission where calibration accuracy limits disc detection through photometry, reaching levels below 1 zodi for stars at <10pc.

Accepted for publication in Astronomy and Astrophysics

References in corpus (29)

• Origin of the Structure of the Kuiper Belt during a Dynamical Instability in the Orbits of Uranus and Neptune
• Debris Disk Evolution Around A Stars
• Transience of hot dust around sun-like stars
• Spitzer IRS Spectroscopy of IRAS-Discovered Debris Disks
• The Complete Census of 70-um-Bright Debris Disks within the FEPS (Formation and Evolution of Planetary Systems) Spitzer Legacy Survey of Sun-like Stars
• Nearby debris disk systems with high fractional luminosity reconsidered
• Long-Term Collisional Evolution of Debris Disks
• Vega is a rapidly rotating star
• Abundant Circumstellar Silica Dust and SiO Gas Created by a Giant Hypervelocity Collision in the ~12 Myr HD172555 System
• Circumstellar material in the Vega inner system revealed by CHARA/FLUOR
• STIS Imaging of the HR 4796A Circumstellar Debris Ring
• Discovery of an 86 AU Radius Debris Ring Around HD 181327
• The History of the Solar System's Debris Disc: Observable Properties of the Kuiper Belt
• The Rise and Fall of Debris Disks: MIPS Observations of h and chi Persei and the Evolution of Mid-IR Emission from Planet Formation
• A near-infrared interferometric survey of debris disk stars. I. Probing the hot dust content around epsilon Eridani and tau Ceti with CHARA/FLUOR
• Spitzer 24 micron Survey of Debris Disks in the Pleiades
• Mid-infrared resolution of a 3 AU-radius debris disk around Zeta Leporis
• Resolving the hot dust around HD69830 and eta Corvi with MIDI and VISIR
• Resolved debris disk emission around eta Tel: a young Solar System or ongoing planet formation?
• Solar System Analogs Around IRAS-Discovered Debris Disks
• An interferometric study of the Fomalhaut inner debris disk. I. Near-infrared detection of hot dust with VLTI/VINCI
• The nature of mid-infrared excesses from hot dust around Sun-like stars
• High-Resolution Imaging of the Dust Disk around 49 Ceti
• Modeling the Infrared Bow Shock at delta Velorum: Implications for Studies of Debris Disks and lambda Bootis Stars
• 12 and 18 micron images of dust surrounding HD 32297
• A Ring of Warm Dust in the HD 32297 Debris Disk
• Discovery of an extended debris disk around the F2V star HD 15745
• Spitzer Far-Infrared Detections of Cold Circumstellar Disks
• VLT/NACO coronagraphic observations of fine structures in the disk of beta Pictoris

Cited by in corpus (13)

• Resolved Debris Discs Around A Stars in the Herschel DEBRIS Survey
• Scientific Discovery with the James Webb Space Telescope
• Structure and evolution of debris disks around F-type stars: I. Observations, database and basic evolutionary aspects
• A Comprehensive Census of Nearby Infrared Excess Stars
• A Sensitive Identification of Warm Debris Disks in the Solar Neighborhood Through Precise Calibration of Saturated WISE Photometry
• Confusion limited surveys: using WISE to quantify the rarity of warm dust around Kepler stars
• Multi-Wavelength Modelling of the Beta Leo Debris Disc: 1, 2 or 3 planetesimal populations?
• Resolved Imaging of the HD191089 Debris Disc
• Resolving the terrestrial planet forming regions of HD113766 and HD172555 with MIDI
• Probing the Terrestrial Regions of Planetary Systems: Warm Debris Disks with Emission Features
• Dusty OB Stars in the Small Magellanic Cloud - I: Optical Spectroscopy Reveals Predominantly Main-Sequence OB Stars
• Debris discs in the 27 Myr old open cluster IC4665
• Dusty OB stars in the Small Magellanic Cloud - II: Extragalactic Disks or Examples of the Pleiades Phenomenon?