Dust emission features in NGC 7023 between 0.35 and 2.5 microns: Extended red emission (0.7 microns) and two new emission features (1.15 and 1.5 microns)

被引:25
作者
Gordon, KD [1 ]
Witt, AN
Rudy, RJ
Puetter, RC
Lynch, DK
Mazuk, S
Misselt, KA
Clayton, GC
Smith, TL
机构
[1] Univ Arizona, Steward Observ, Tucson, AZ 85721 USA
[2] Univ Toledo, Ritter Astrophys Res Ctr, Toledo, OH 43606 USA
[3] Aerosp Corp, Space Sci Applicat Lab, Los Angeles, CA 90009 USA
[4] Univ Calif San Diego, Ctr Astrophys & Space Sci, La Jolla, CA 92093 USA
[5] Louisiana State Univ, Dept Phys & Astron, Baton Rouge, LA 70803 USA
关键词
dust; extinction; infrared : ISM : lines and bands; ISM : individual (NGC 7023); ISM : lines and bands; reflection nebulae;
D O I
10.1086/317245
中图分类号
P1 [天文学];
学科分类号
0704 ;
摘要
We present 0.35-2.5 mum spectra of the south and northwest filaments in the reflection nebula NGC 7023. These spectra were used to test the theory of Seahra & Duley that carbon nanoparticles are responsible for extended red emission (ERE). Our spectra fail to show their predicted second emission band at 1.0 mum even though both filaments exhibit strong emission in the familiar 0.7 mum ERE band. The northwest filament spectrum does show one, and possibly two, new dust emission features in the near-infrared. We clearly detect a strong emission band at 1.5 mum which we tentatively attribute to beta -FeSi2 grains. We tentatively detect a weaker emission band at 1.15 mum which coincides with the location expected for transitions from the conduction band to midgap defect states of silicon nanoparticles. This is added evidence that silicon nanoparticles are responsible for ERE as they already can explain the observed behavior of the main visible ERE band.
引用
收藏
页码:859 / 866
页数:8
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