Dust in the inner regions of debris disks around a stars
Abstract
We present infrared interferometric observations of the inner regions of two A-star debris disks, β Leo and ζ Lep, using the FLUOR instrument at the CHARA interferometer on both short (30 m) and long (> 200 m) baselines. For the target stars, the short-baseline visibilities are lower than expected for the stellar photosphere alone, while those of a check star, δ Leo, are not. We interpret this visibility offset of a few percent as a near-infrared (NIR) excess arising from dust grains which, due to the instrumental field of view, must be located within several AU of the central star. For β Leo, the NIR excess-producing grains are spatially distinct from the dust which produces the previously known mid-infrared (MIR) excess. For ζ Lep, the NIR excess may be spatially associated with the MIR excess-producing material. We present simple geometric models which are consistent with the NIR and MIR excesses and show that for both objects, the NIR-producing material is most consistent with a thin ring of dust near the sublimation radius, with typical grain sizes smaller than the nominal radiation pressure blowout radius. Finally, we discuss possible origins of the NIR-emitting dust in the context of debris disk evolution models.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- February 2009
- DOI:
- 10.1088/0004-637X/691/2/1896
- arXiv:
- arXiv:0810.3701
- Bibcode:
- 2009ApJ...691.1896A
- Keywords:
-
- circumstellar matter;
- stars: individual: β Leo ζ Lep;
- Astrophysics
- E-Print:
- 20 pages, 2 figures, to appear in the Astrophysical Journal