http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
- 中文 을 입력하시려면 zhongwen을 입력하시고 space를누르시면됩니다.
- 北京 을 입력하시려면 beijing을 입력하시고 space를 누르시면 됩니다.
RISS 인기검색어
- 검색키워드
- 저자 : Sorahana, S. (검색결과 2 건)
- 무료
- 기관 내 무료
- 유료
-
NEW INSIGHT ON BROWN DWARF ATMOSPHERES REVEALED BY AKARI
Sorahana, S.,Yamamura, I. The Korean Astronomical Society 2012 天文學論叢 Vol.27 No.4
We present the latest results from the Mission Program NIRLT, the NIR spectroscopic observations of brown dwarfs using the IRC on board AKARI. The near-infrared spectra in the wavelength range between 2.5 and $5.0{\mu}m$ is especially important to study the brown dwarf atmospheres because of the presence of non-blended bands of major molecules, including $CH_4$ at $3.3{\mu}m$, $CO_2$ at $4.2{\mu}m$, CO at $4.6{\mu}m$ and $H_2O$ around $2.7{\mu}m$. Our observations were carried out in the grism-mode resulting in a spectral resolution of ~ 120. In total, 27 sources were observed and 18 good spectra were obtained. We investigate the behavior of three molecular absorption bands, CO, $CH_4$ and $CO_2$, in brown dwarf spectra relative to their spectral types. We find that the $CH_4$ band appears in the spectra of dwarfs later than L5 and CO band is seen in the spectra of all spectral types. $CO_2$ is detected in the spectra of late-L and T type dwarfs.
-
A SIGNATURE OF CHROMOSPHERIC ACTIVITY IN BROWN DWARFS: A RECENT RESULT FROM NIRLT MISSION PROGRAM
Satoko Sorahana,Takeru K. Suzuki,ISSEI YAMAMURA 한국천문학회 2017 天文學論叢 Vol.32 No.1
We present the latest results from the Mission Program NIRLT (PI: I.Yamamura), the near-infrared spectroscopy of brown dwarfs using the AKARI/IRC grism mode with the spectral resolution of $\sim120$. The near-infrared spectra in the wavelength range between 2.5 and 5.0~$\mu$m are especially important to study the brown dwarf atmospheres because of the presence of major molecular bands, including CH$_4$ at 3.3~$\mu$m, CO$_2$ at 4.2~$\mu$m, CO at 4.6 ~$\mu$m, and H$_2$O around 2.7~$\mu$m. We observed 27 sources, and obtained 16 good spectra. Our model fitting reveals deviations between theoretical model and observed spectra in this wavelength range, which may be attributed to the physical condition of the upper atmosphere. The deviations indicate additional heating, which we hypothesize to be due to chromospheric activity. We test this effect by modifying the brown dwarf atmosphere model to artificially increase the temperature of the upper atmosphere, and compare the revised model with observed spectra of early- to mid-L type objects with H$\alpha$ emission. We find that the chemical structure of the atmosphere changes dramatically, and the heating model spectra of early-type brown dwarfs can be considerably improved to match the observed spectra. Our result suggests that chromospheric activity is essential to understand early-type brown dwarf atmospheres.
ScienceON
코리아스칼라연관 검색어 추천
이 검색어로 많이 본 자료
활용도 높은 자료
