1、san asked me how I liked the party. She asked me if I had got her bag. 定语从句（非限定性和限定性） ： 他买了那条我为他挑选的裤子. 这是她住的屋子. 去年加入我们的设计员工作很努力. 反意疑问句：doesnt she; shall we; did you. 看到/听到/感觉到某事正在发生: 我看到她上了公共汽车。I saw her getting on the bus. 动词-ing 形式和动词不定式 to do: 下面哪句对,哪句错? (对;错;错.) 表示义务/责任/不允许/不必的 have to, must 和 b
2、e allowed to, mustnt, dont have to 的用法: 选词填空:must; have to; mustnt; dont have to. 介词词组 in spite of, apart from 和 except for: In spite of; Except for. 对对方的说法表示同感 neither, nor, noteither, so: I dont smoke, neither does he. Tim has lost his camera, so has Mary. 日积月累: 短语动词:be worried about, give up, be
3、fed up with, get on with, look after, look for, agree with, pick out, write out, help sb with sth, apply for, be patient with, be interested in. 表示方位的短语:on the right/left, at the back/front, in the middle, top right, bottom left. 表示否定意义的前缀:un- im- in- dis- 开放英语(2)作业 3 一部分：1A 2B 3A 4B 5A 二部分：6C 7A 8C
4、 9A 10A 11A 12C 13B 14B 15B 16C 17A 18B 19C 20B 21B 22B 23C 24A 25B 三部分：26.He stole the laptop.（改为被动语态） The laptop was stolen by him. 27.Tim didnt go to work the next day. He cleaned up the flat.（用 instead of 将两句合成一句） Tim cleaned up the flat the next day instead of going to work. 28.“I cant find my
5、notebook,” she said.（改为间接引语） She said that she couldnt find her notebook. 29.It was a place. He wanted to go there.（用 where 将两句合成一句） It was a place where he wanted to go. 30.Tim has lost his camera. I have lost my camera.（用 so 将两句合成一句） Tim has lost his camera, so have I. 四部分：31.A 32.B 33.C 34.B 35.A
6、 36.B 37.A 38.A 39.B 40.A 五部分：41.我昨天让人把窗户擦了 42.他过去常每到星期天去打篮球 43.他们在晚会上玩得很开心 44.她不喜欢游泳，她妹妹也一样 45.三年来我一直在学英语 开放英语(2)期末自测 一部分：1B 2B 3A 4A 5A 二部分：6A 7C 8C 9B 10B 11A 12C 13A 14A 15C 16A 17B 18A 19C 20C 21A 22A 23C 24A 25B 三部分：26.I was too hot. I couldnt open the window.（用 but 将两句连成一句） I was too hot, but
7、 I couldnt open the window. 27. Although it rained, the visit was a success.（用 In spite of 将两句连成一句） The visit was a success in spite of rain. 28. Im tall and thin. My mother is too.（用 so 将两句连成一句） Im tall and thin, so is my mother. 29. They are going to look after the cat.（用 What 针对 the cat 改写句子） Wha
8、t are they going to look after? 30.He disturbed the burglars.（用被动语态改写句子） The burglars were disturbed by him. 四部分：31.B 32.B 33.A 34.B 35.A 36.B 37.A 38.B 39.A 40.B 五部分：41.他在北京西部的一个大学学习 42.他在他朋友的屋子里偶然看到了一幅旧油画 43.如果她赢了彩票，她将会买一间大房子 44.这间公寓有点儿乱 45.这两个男孩都擅长于唱歌 arXiv:astro-ph/0405405v1 20 May 2004 Neutral
9、Hydrogen in Arp 158 Mansie G. Iyer and Caroline E. Simpson Department of Physics, Florida International University, Miami, Fl 33199 miyer01fiu.edu, simpsoncfiu.edu Stephen T. Gottesman Department of Astronomy, University of Florida, Gainesville, FL 32611 gottastro.ufl.edu and Benjamin K. Malphrus De
10、partment of Physical Sciences, Morehead State University, Morehead, KY 40351 b.malphrusmorehead-st.edu ABSTRACT We present 21 cm observations of Arp 158. We have performed a study of the neutral hydrogen (Hi) to help us understand the overall formation and evolution of this system. This is a disturb
11、ed system with distinct optical knots connected by a linear structure embedded in luminous material. There is also a diff use spray to the southeast. The Hi seems to be made up of three distinct, kinematically separate systems. Arp 158 bears a certain optical resemblance to NGC 520 (Arp 157), which
12、has been identifi ed as a mid- stage merger. From our 21 cm observations of Arp 158, we also see a comparable Hi content with NGC 520. These similarities suggest that Arp 158 is also an intermediate stage merger. Subject headings: galaxies: interacting individual galaxy (Arp 158) ISM: Hi 1.INTRODUCT
13、ION In the early seventies, Toomre (1970) and Toomre the third knot is located approximately in the center of the linear structure. The westernmost “nucleus” was examined by Chincarini Clark 1980) to reduce the eff ect of the sidelobes produced by non-gaussian features of the synthesized beam (the “
14、dirty” beam). We tested various weighting schemes (robust parameter in the IMAGR task in AIPS) during the imaging process to increase the resolution, but because of the lack of baselines less than 1k, the increase in resolution was not worth the corresponding decrease in sensitivity. The higher reso
15、lution images did not reveal any new morphological or kinematic features, and with the lowered sensitivity, low column density features were lost completely. Hence, in order to maximize the sensitivity to low surface brightness features, we used the natural weighting scheme, resulting in a beamsize
16、(FWHM) of 47.3 42.2 . The data cube was cleaned down to 0.98 mJy per beam, corresponding to 1 as determined by the statistical analysis of a signal-free channel map. Line emission signal was present in channels from 41 to 89, approximately 4500 km s1to 5000 km s1, which were then integrated to produ
17、ce moment maps representing the Hi integrated column density (0th moment), the temperature-weighted mean velocity (1st moment), 4 and the velocity dispersion (2nd moment). 3.Results 3.1.Hi Spatial Distribution, Column Densities and Masses Throughout this paper we use a value of H0equal to 75 km s1Mp
18、c1and a heliocentric velocity of 4758 km s1( NASA IPAC Extragalactic Database, NED2) for Arp 158. These values imply a distance of 63 Mpc. The results from the derived quantities are shown in Table 3, and are discussed below. Figure 2 is a grayscale image of the Hi integrated fl ux density. We can s
19、ee that there are three distinct Hi concentrations which we denote as A, B, and C. Figure 3 represents the optical image from the second generation blue Digitized Sky Survey (DSS2)3overlaid with Hi contours. The central optical knot is more easily visible in this image. For the entire distribution,
20、we have detected a total Hi mass of 6.5 109M. System A, which has the highest beam-smoothed Hi column density (NHI= 13.0 1020atoms cm2) coincides with the optical knot system and seems to be centered to the west of the western knot/star. System B (NHI= 7.4 1020atoms cm2 ) appears to coincide with th
21、e diff use tail to the south-east. There is also a very interesting gas knot to the north-west of the galaxy. This is system C (NHI= 1.2 1020 atoms cm2 ). Note that the fi eld of view for Arps image (Figure 1) does not include this area. Although this system is faint in Hi it does appear in four con
22、tiguous channels and we believe it to be a valid detection. Using separate integration maps, we have calculated Hi masses associated with each of our defi ned systems (see section on kinematics), as well as their fl ux-weighted systemic velocities (Table 3), and an estimate of their velocity widths
23、(FWHM). System A has the highest Hi mass (2.9 109M) and the Hi masses associated with systems B and C are approximately 1.9 109Mand 0.1 109M, respectively. Using the optical angular size (2.5 0.7) catalogued in NED, the optical dimensions for Arp 158 are 46 13 kpc. The total Hi distribution is sprea
24、d well beyond the optical image. We measure an Hi extent of 70 33 kpc (not deconvolved), measured out to 2 1019atoms cm2. Looking at Figure 3, there is faint optical emission located north and very slightly east of the Hi. The northernmost part of the Hi contour might overlay the southernmost part o
25、f the optical emission, but the Hi is not obviously coincident with this weak optical emission. A deeper optical image is needed to establish its nature and a spectrum would be required to establish any physical connection to Arp 158. 2http:/nedwww.ipac.caltech.edu 3http:/skyview.gsfc.nasa.gov 5 3.2
26、.Kinematics Figure 4 shows the intensity-weighted velocity map. The isovelocity contours are very diff erent for systems A and B, and there is an area of steep gradient between the two which overlies the bright optical emission in the system. There also appear to be three distinct kinematic areas co
27、inciding with systems A, B, and C. The apparent kinematical axes of systems A and B, as indicated by the isovelocity contours, are oriented in diff erent directions. The position angle of the kinematic axis for system A, measured from north through east, is approximately 25on the western side, rotat
28、ing to a position angle of approximately 90on the eastern side. This almost 70kink in the isovels in system A shows that this is a fairly abrupt change. For system B, the position angle is approximately 150. The channel maps (Figure 5) for Arp 158 reveal that there is emission in every channel betwe
29、en systems A and B, showing that there is gas extending between them which is superposed along the line-of-sight in the moment maps. The extended emission could be either a bridge or a tail. It could be that systems A and B were two diff erent galaxies that are now interacting. In this case, we coul
30、d consider the extended emission to be a bridge. We do not believe this to be the case. Optically, systems A and B do not have separate nuclei. The distinct optical knots only seem to coincide with system A, whereas system B does not have much of a stellar component associated with it. It seems more
31、 likely that B is a tidal tail that formed due to the interaction that deformed the optical components of the system. The center point in each of the channel maps is moving smoothly to the west going to higher velocities. The contours for system B show a smooth run in velocity, with a few widely sep
32、arated isovels indicating a shallow observed gradient in velocity. It also exhibits a sharp cut-off in velocity space at the westernmost end. Thus system B, which optically resembles a tail, also stretches out in the Hi and has a narrow spread in velocity. All these properties are consistent with th
33、is feature being a tidal tail (Hibbard they may be Hii regions (C east is to the left. The photographic emulsion 103a-D was used to obtain the image. 12 DECLINATION (J2000) RIGHT ASCENSION (J2000) 01 25 35302520151005 34 04 03 02 01 00 33 59 A B C Fig. 2. Integrated Hi for Arp 158. The contour level
34、s are (2, 12, 22, 32, 42, 52, 62, 72, 82, 92, 102, 112, 122, 132, 142) 1019atoms cm2, where 1019atoms cm2= 18.09 Jy beam1m s1. The letters A, B and C represent the three diff erent gas components of Arp 158. The enscribed ellipse in this fi gure and the following moment maps represents the beam size
35、 (FWHM = 47.3 42.2). 13 Fig. 3. The blue DSS2 optical image of Arp 158 with integrated Hi fl ux density contours. The contour levels are those used in Figure 2. The cross represents the position of the weak optical emission. 14 440046004800 DECLINATION (J2000) RIGHT ASCENSION (J2000) 01 25 353025201
36、51005 34 04 03 02 01 00 33 59 A B C Fig. 4. Temperature weighted mean velocity map of Arp 158. Contours are plotted every 30 km s1from 4580 to 4940 km s1. 15 Fig.5a. Hi channel maps of Arp 158 are contoured on the optical blue DSS2 image.The heliocentric velocity for each channel is listed in the up
37、per right corner. The crosses represent systems C, A, and B, from upper right to lower left respectively. Contours are at -2, 2, and then increase by 2. 1 = 0.98 mJy beam1. The highest contour is at 15.52 mJy beam1 and the dashed lines represent negative contours. 16 Fig. 5b. Channel Maps (continued
38、). 17 Fig. 5c. Channel Maps (continued). 18 Fig. 5d. Channel Maps (continued). 19 VELOCITY (KM/S) RELATIVE RIGHT ASCENSION (ARCSEC) 3002001000-100-200-300 -300 -200 -100 0 100 200 300 A B C Fig. 6a. Position-Velocity diagrams for Arp 158. Velocity relative to the systemic velocity (4758 km s1 ) vs.
39、right ascension relative to the center of the fi eld (01h25m19.7s). Contours are plotted at (-100, -90, .,+90, +100) % of the peak fl ux, which is 0.078 Jy beam1. 20 VELOCITY (KM/S) RELATIVE DECLINATION (ARCSEC) -300-200-1000100200300 -300 -200 -100 0 100 200 300 A B C Fig. 6b. Declination relative
40、to the center of the fi eld (340128) vs. velocity relative to the systemic velocity. The contours are percentages of the peak fl ux, as for (a); however in this case, the peak fl ux is 0.105 Jy beam1 . The boxes in each of these fi gures approximately represent the velocity ranges used for producing
41、 the moment maps in Figure 7. 21 45004550460046504700 DECLINATION (J2000) RIGHT ASCENSION (J2000) 01 25 35302520151005 34 04 03 02 01 00 33 59 A C Fig. 7a. Temperature-weighted mean velocity maps of Systems A and C. The contours are plotted every 10 km s1from 4540 to 4680 km s1. 22 49004920494049604
42、980 DECLINATION (J2000) RIGHT ASCENSION (J2000) 01 25 35302520151005 34 04 03 02 01 00 33 59 B Fig. 7b. Temperature-weighted mean velocity map of system B. The contours are plotted every 10 km s1from 4928 to 4968 km s1. 23 4700475048004850 DECLINATION (J2000) RIGHT ASCENSION (J2000) 01 25 3530252015
43、1005 34 04 03 02 01 00 33 59 Tail Fig. 7c. Temperature-weighted mean velocity map of the “tail” connecting systems A and B. The contours are plotted every 10 km s1from 4705 to 4885 km s1. 24 Fig. 8. Velocity profi le of systems A, B, and C. 25 Fig. 9a. The blue DSS2 optical image with integrated Hi continuum contours. The contours are drawn at (10, 20, 30, 40) 0.26 mJy beam1(0.26 mJy beam1= 1 ). 26 DECLINATION (J2000) RIGHT ASCENSION (J2000) 01 25 35
