INTERSTELLAR EXTINCTION LAW TOWARD THE GALACTIC CENTER III: J, H, KS BANDS IN THE 2MASS AND THE MKO SYSTEMS, AND 3.6, 4.5, 5.8, 8.0 μm IN THE SPITZER/IRAC SYSTEM
INTERSTELLAR EXTINCTION LAW TOWARD THE GALACTIC CENTER III: J, H, KS BANDS IN THE 2MASS AND THE MKO SYSTEMS, AND 3.6, 4.5, 5.8, 8.0 μm IN THE SPITZER/IRAC SYSTEM
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DOI：
10.1088/0004-637x/696/2/1407
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发表时间：
2009-02
期刊：
影响因子：
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通讯作者：
S. Nishiyama;M. Tamura;H. Hatano;D. Kato;T. Tanabé;K. Sugitani;T. Nagata
中科院分区：
文献类型：
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作者：
S. Nishiyama;M. Tamura;H. Hatano;D. Kato;T. Tanabé;K. Sugitani;T. Nagata
利用IRSF/SIRIUS近红外巡天（NIR）、2 μ m全天巡天（2 MASS）和Spitzer/IRAC/GLIMPSE II星表中的点源，确定了1.2 ~ 8.0 μm波段银河系中心（GC）的星际消光律。用IRSF望远镜和SIRIUS照相机在J、H和KS波段对中心区域进行了测量，SIRIUS照相机的滤光片类似于莫纳克亚山天文台（MKO）的近红外测光系统。结合GLIMPSE II点源星表，我们制作了KS与KS − λ色星等图（CMD），其中λ=3.6、4.5、5.8和8.0 μm。膨胀红团簇星的KS星等和红巨星分支的KS − λ色被用作CMD中红化矢量的示踪。从这些幅度和颜色，我们已经获得了四个IRAC波段的总消光比选择性消光比。结合Nishiyama等人导出的J和H带，对于朝向GC的视线，我们获得AJ：AH：：A[3.6]：A[4.5]：A[5.8]：A[8.0] = 3.02：1.73：1：0.50：0.39：0.36：0.43。根据最近的研究，这证实了从较短波长处的幂律消光的简单外推，λ <$3 μm处的消光曲线变平。计算了2 MASS J、H和KS波段的消光规律，发现与MKO系统的消光规律吻合较好，从而确定J、H和KS波段的消光符合Aλ <$λ−2.0向GC方向急剧下降的幂律。在附近的分子云和弥漫的星际介质中，缺乏对总消光比和选择性消光比的可靠测量阻碍了消光定律的明确确定;然而，对这些视线的观测结果不能与单一的消光定律相协调。
We have determined interstellar extinction law toward the Galactic center (GC) at the wavelength from 1.2 to 8.0 μm, using point sources detected in the IRSF/SIRIUS near-infrared (NIR) survey and those in the Two Micron All Sky Survey (2MASS) and Spitzer/IRAC/GLIMPSE II catalogs. The central region ∣l ∣ ≲3.°0 and ∣b ∣ ≲1.°0 has been surveyed in the J, H, and KS bands with the IRSF telescope and the SIRIUS camera whose filters are similar to the Mauna Kea Observatories (MKO) NIR photometric system. Combined with the GLIMPSE II point source catalog, we made KS versus KS − λ color–magnitude diagrams (CMDs) where λ=3.6, 4.5, 5.8, and 8.0 μm. The KS magnitudes of bulge red clump stars and the KS − λ colors of red giant branches are used as a tracer of the reddening vector in the CMDs. From these magnitudes and colors, we have obtained the ratios of total-to-selective extinction for the four IRAC bands. Combined with for the J and H bands derived by Nishiyama et al., we obtain AJ:AH::A[3.6]:A[4.5]:A[5.8]:A[8.0] = 3.02:1.73:1:0.50:0.39:0.36:0.43 for the line of sight toward the GC. This confirms the flattening of the extinction curve at λ ≳ 3 μm from a simple extrapolation of the power-law extinction at shorter wavelengths, in accordance with recent studies. The extinction law in the 2MASS J, H, and KS bands has also been calculated, and good agreement with that in the MKO system is found. Thus, it is established that the extinction in the wavelength range of J, H, and KS is well fitted by a power law of steep decrease Aλ ∝ λ−2.0 toward the GC. In nearby molecular clouds and diffuse interstellar medium, the lack of reliable measurements of the total-to-selective extinction ratios hampers unambiguous determination of the extinction law; however, observational results toward these lines of sight cannot be reconciled with a single extinction law.