2017年IAO理论低年组第5题-涡状星系

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英文题目

α-5. Whirlpool galaxy. An imaging observation of Messier object M51, consisted of galaxy NGC 5194 (α=13^h29^m6^s, δ=+47°13’50") and its companion NGC 5195, was made by the 1-m telescope of Weihai Observatory (WHO), on December 25, 2014. The V-band image is shown in Fig.a5. (see separate sheet), the bounding box marks the field of view of the image taken by the telescope (with focal length of 8 meters) and the PI CCD (2048 x 2048, pixel size 13.5 μm x 13.5 μm).

5.1. Find the Beijing time (UTC+08, write the answer in 24h format: hh:mm) of the upper culmination of NGC 5194 in Weihai Observatory on the observing date, in form of «T_c = ...».

5.2. Estimate the angular size (diameter) of NGC 5194 (in units of arc minutes, write the answer in form of «β= ...»).

5.3. If the physical size of NGC 5194 is known as about half the size of the Milky Way Galaxy, estimate the distance to M51 (in units of Mpc, write the answer in form of «L= ...»).

5.4. Which is the morphological type of NGC 5194 ("elliptical", "spiral", "barred spiral", "irregular")? Write the answer in English in form of «Type= ...».