High-resolution 25 μm imaging of the disks around Herbig AE/BE stars

M. Honda, K. Maaskant, Y. K. Okamoto, H. Kataza, T. Yamashita, T. Miyata, S. Sako, T. Fujiyoshi, I. Sakon, H. Fujiwara, T. Kamizuka, G. D. Mulders, E. Lopez-Rodriguez, C. Packham, T. Onaka

Research output: Contribution to journalArticlepeer-review

16 Scopus citations

Abstract

We imaged circumstellar disks around 22 Herbig Ae/Be stars at 25 μm using Subaru/COMICS and Gemini/T-ReCS. Our sample consists of an equal number of objects from each of the two categories defined by Meeus et al.; 11 group I (flaring disk) and II (flat disk) sources. We find that group I sources tend to show more extended emission than group II sources. Previous studies have shown that the continuous disk is difficult to resolve with 8 m class telescopes in the Q band due to the strong emission from the unresolved innermost region of the disk. This indicates that the resolved Q-band sources require a hole or gap in the disk material distribution to suppress the contribution from the innermost region of the disk. As many group I sources are resolved at 25 μm, we suggest that many, but not all, group I Herbig Ae/Be disks have a hole or gap and are (pre-)transitional disks. On the other hand, the unresolved nature of many group II sources at 25 μm supports the idea that group II disks have a continuous flat disk geometry. It has been inferred that group I disks may evolve into group II through the settling of dust grains into the mid-plane of the protoplanetary disk. However, considering the growing evidence for the presence of a hole or gap in the disk of group I sources, such an evolutionary scenario is unlikely. The difference between groups I and II may reflect different evolutionary pathways of protoplanetary disks.

Original languageEnglish
Article number143
JournalAstrophysical Journal
Volume804
Issue number2
DOIs
StatePublished - 10 May 2015
Externally publishedYes

Keywords

  • circumstellar matter
  • protoplanetary disks
  • stars: pre-main sequence

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