Printable Manual - Department of Physics and Astronomy
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1. Save as type PIC Files pic Ready Range Auto Figure 15 Saving your image Page 11 External Resources Before starting your investigation or once you have analysed your images you might want to consider the following resources Galaxy Collision Multi media presentations from HubbleSite on galaxies and their collisions http hubblesite org explore_astronomy cosmic_collision Cosmos Swinburne University s online astronomy encyclopedia has many articles that should be appropriate for a high school audience http astronomy swin edu au cosmos Crashing Galaxies This project from the Faulkes Telescope UK site uses the Galaxy Crash Java applet http burro astr cwru edu JavaLab GalCrashWeb to allow students to collide their own galaxies It contains teacher notes and student worksheets to guide you through using the applet http faulkes telescope com education galaxies crashing_galaxies Observing Interacting Galaxies This project from the Faulkes Telescope UK site is a straightforward project to image a number of interacting galaxies in colour and then to identify different features visible in the images It contains worksheets and other resources http faulkes telescope com education projects galaxies observing_interacting_galaxies Galaxy Interactions Supercomputing simulations of galaxy interactions from the Hayden Planetarium A short explanation accompanies each simulation http naydenplan2. websites see the External Resources section for links Downloads From here you can download everything you need to get you started with the Interacting Galaxies project 1 Download and install IRIS You can download IRIS from the IRIS home page and install or simply use the version provided in this package You may need to select the file SETUP EXE to start the installation Note The default install directory is C iris You will probably want to change this to C Program Files or something similar The installation program asks you for this directory Once installed you may want to right click on iris exe to create a shortcut which you can then drag to the desktop or other appropriate place Follow the instructions for Configuring IRIS to set your working path to C data or preferred directory 2 Downloading Practice Archive Data One of the best ways to learn how to use IRIS and how to analyse your interacting galaxies is to practice on some real data Please download the data included in this package from the Faulkes Telescope North for any or all of the six sets of interacting galaxies Each set contains a red R blue B and green V or visual image Save the files to your hard drive in the directory C DATA or preferred directory Page 1 Selecting Interacting Galaxies to Observe This section is only relevant if you plan to sign up for the Faulkes Telescope Project in order to make your own observations It is not
3. Aladdin is much larger than what you will see with the Faulkes Telescope The Aladdin Applet is slower but allows you to interact with the returned data and reduce the field of view to something similar to what you would see with the Faulkes Telescopes Figure 5 shows the full field of view of approximately 13 x 13 returned by the Aladdin Applet However you can adjust the field of view by altering the Zoom level on the right hand side from 2 3x Adjusting this to be Zoom 2x as in Figure 6 you now have a field of view of approximately 4 3 x 4 1 which is approaching that of the Faulkes Telescopes In this case the images from the Faulkes Telescopes would show slightly more than what you can see here You can see from this image that NGC 3395 is a good example of a pair of interacting galaxies to observe as the pair almost fills the field of view Page 3 ASISTM Faulkes Telescope Deep Space in the Classroom http www astronomy mq edu au deepspace VV 246b in POSSI E DSS1 Central coordinates of the field J2000 RA 10 49 50 0 Dec 32 58 57 Size and definition 14 1 x 14 1 500 x 500 pixels Survey Palomar Observatory Sky Survey POSSI Color Red E Origine Space Telescope Science Institute STScI Digitizing machine Plate Densitometer Scanner PDS Available image s 2MASS H Fits 2MASS J Fits 2MASS K Fits IRAS IRIS 25MU Fits POSSI O DSS2 Jpeg POSSIVF DSS2 Jpeg POSSII J DSS2 Jpeg POS
4. X 2E RP98b IG VV Rad A86 IR RAS ICRS coord ep 2000 eq 2000 10 49 50 08 32 58 57 7 Unknown 1950 00 1600 00 90 D 1999ApJS 125 409C FK5 coord ep 2000 eq 2000 1049 50 08 32 58 57 7 Unknown 1950 00 1600 00 90 D 1999Ap S 125 409C FK4 coord ep 1950 eq 1950 10 47 02 94 33 14 51 3 Unknown 1950 00 1600 00 89 D 1999Ap S 125 409C Gal coord ep 2000 eq 2000 192 9211 63 1432 Unknown 1950 00 1600 00 90 D 1999ApJS 125 409C Radial velocity Redshift cz cz 1634 0 12 0 D 1999PASP 111 438F Morphological type Se D Angular size arcmin 1 949 1 148 50 D Fluxes 5 B 12 1 D 1999PASP 111 438F V 12 10 D J 10 764 0 021 C 2006AI 13 1 11635 Figure 9 SIMBAD query results Look up the cz value for the object under the Radial velocity redshift cz section In this case it is 1634 0 km s The distance to the galaxy in Mpc can now be found using the following equation D Mpc cz Ho where Ho is the Hubble constant which we will set at 70 km s Mpc 6 Determine the size of the galaxy in Mpc using the small angle formula The appendix taken from http cosmos phy tufts edu zirbel laboratories AstrometryPreLab pdf explains the derivation of the small angle formula You may also refer to Part 1 Step 6 of the Age of a Planetary Nebula teaching module for further explanation The calculation for the above galaxy would be Size in Mpc Dist to gal in Mpc gal s
5. image file for the interacting galaxies you wish to study Adjust the threshold levels until you think you can discern the edges of the galaxies or click on View Modified Equalization NGC 3395 is used for this example 2 Mark the edges of the galaxies Students must decide where they think the edge of each galaxies lies There may be significant differences depending on the threshold or display settings each student has decided to use and this can be a topic for discussion in class How do you decide where the galaxy finishes Select Analysis Select Objects Page 5 ASISTM Faulkes Telescope Deep Space in the Classroom http www astronomy mgq edu au deepspace O Iris ersion 5 33 c data faulkes uni high ngc3395_v fit File view Geometry Preprocessing Processing Spectro Analysis Data Base Digital photo Video Help os ba ef ml sjaj Aperture photometry Magnitude constant Select Objects Automatic photometry Automatic astrometry Ephemeris of Mars Ephemeris of Jupiter Display data SUP The cursor will change shape and an Output window will pop up on the screen Click at one edge of one of the galaxies and the x y coordinates will appear in the Output window Click at the other edge of the same galaxy and these x y coordinates will also appear in the Output window File Edit Object 1 392 599 Object 2 589 366 Figure 8 Coordinat
6. in the Classroom http www astronomy mq edu au deepspace CDY SIMBAD Query by identifiers ian RONOMIQUES DE STRASBOUR CDS Simbad VizieR Aladin Catalogues Nomenclature Biblio Tutorial Developer s corner other query Identifier Coordinate Criteria Bibliography Script Output Help modes query query query query submission options Query an identifier Examples Identifier sirius M31 MCG 02 60 010 How to write an identifier can be found in the dictionary of nomenclature IAU format can also be used with the following format iau J B 1230 08 enlarging factor Object type ngc3395 you can choose to query only this object around the object define a radius 2 arcmin submit id clear Query a list of identifiers Figure 2 SIMBAD query This returns a page with a large amount of data on the object you have just identified Scroll down the page until you see the section labelled Plots and Images as in Figure 3 Click on either the Aladdin Previewer or Aladdin Applet buttons to view your object Plots and Images plot around Aladin previewer Aladin applet radius 10 arcmin Figure 3 SIMBAD results The Aladdin Previewer is faster and returns a simple image of the area As can be seen on the right hand side of Figure 4 the Size and Definition is 14 1 x 14 1 much larger than the 5 x 5 of the Faulkes Telescope field of view This means that the image downloaded by
7. necessary if you are only using the archive data available from the Downloads section 1 Download the Planner Download the Observation Planner for Interacting Galaxies Excel file from the Faulkes Telescope North project page on Interacting Galaxies 2 Obtain a list Input the date you plan to take your observations in the Visibility Calculator as in Figure 1 In this case the observing date is set to the 1st April 2007 FAULKES TELESCOPES OBJECT VISIBILITY CALCULATOR riten by Richard Beare Institute of Education University of Warwick for the Faulkes Telescope Project 15th November 2004 DAY dd ea Use Summer peer time in the UK ri wie K FAULKES TELESCOPE IMPORTANT NOTE also check lower down table for entries Objects visible for a WHOLE half hour slot by in Hawaii and Australia jms name upe arema now enoaan cao sce saosna A A A A 5 30 6 0 2 shown by H and A dashes mean never visible from the location chains of galaxies uncertain probably filaments groups of galaxies interacting elliptical companions connected arms connected to spirals connected to spirals uncertain probably filaments chainsof galaxies long filaments uncertain probably filaments interacting long filaments 0 A IC 563 64 Hickson 40 NGC 2881 NGC 3226 27 NGC 3395 96 UGC 5984 105B5 2 B UGC 6204 Hickson 56 part MCG 10 17 005 comp NGC 369
8. 0 NGC 3769 A NGC 3786 88 j eal oonan wN a EIES Cito eee Soo pte ie np 2 fee feo alle oa alls oa ONES Figure 1 Observation Planner This returns a list of the galaxies visible at various times of night from Hawaii and Australia It also gives you a short description of the interacting galaxies in the column Further info and the size of the interacting galaxies in the column Size arcmin 3 Select potential galaxies based on size The field of view of the Faulkes Telescopes is approximately 5 arcminutes Therefore in order to fill your image with the interacting galaxies and make sure each galaxy is large enough to be studied visually you should choose those interacting galaxies with a Size arcmin of around 5 If Size arcmin is greater than 5 there is an added level of complexity as you will need to mosaic the images The galaxies NGC3395 96 with a field of view of 3 5 are selected for this example 4 View the galaxies in the Aladdin Viewer To see what you can expect from your observations you can view online images of your galaxies This is particularly useful if you would like your students to study particular types of interacting galaxies Go to the SIMBAD Astronomical Database as in Figure 2 input the identifier in this example ngc3395 of your selected interacting galaxies in the Identifier field and click the Submit Id button Page 2 ASISTM Faulkes Telescope Deep Space
9. DY S Apply Clear Start with the visual green image Green is checked in Panel A and try to align it with the red image Start with a coarse adjustment of 2 pixels input 2 0 into the Step field in Panel C Now using the controls in Panel B move the green image until it lines up better with the red Page 9 ASISTM Faulkes Telescope Deep Space in the Classroom http www astronomy mq edu au deepspace image What you are trying to do is make the stars round and their centres white when you combine red green and blue light you end up with white light You will need to adjust the Step to be much smaller as the alignment improves Repeat this for the Blue image Do not click OK until after you have completely finished lining up the images Once you are satisfied with your alignment click OK O Iris ver 15 x sial mlel slal z ol elel Threshold xi p Range Auto 4 Figure 13 Aligned You will notice in this example that the stars have a reddish ring around the outside The red images are slightly larger than the others This may be due to observing conditions different exposure times for the different coloured images or variations in the transmission of light through the different filters Unfortunately there is not a lot you can do about this 6 Adjust the White Balance In an effort to eliminate the reddish cast the image has select View White Balanc
10. Interacting Galaxies Contents DANE EC CLC GEN ON sc rsa oar a ec cr ca Sar ed a ot ae ca oe 1 PWIA AS os cde T ches shoe esas cece cace hk sec ches ged seca she hes a hee see hed eet 1 Selecting Interacting Galaxies to Observe ccccceeeeneeeeeeeeeeeeeeeeeeeeeeeeeeees 2 Measuring the sizes of the Galaxies 0 eee eeeeeeeeeeeeeeeenees 5 Making a Colour Image in IRIS cccecceeeeeeeeeeeeeeeeeeeeeeeeeeeaeeaeaeeaeeeeeeeeeeeeeaaes 8 External RESOUICES 65 626 cre i as oo ot oe ee k nae 12 Introduction With the images seen in the popular media it is easy to believe that galaxies are isolated bodies in the Universe However most galaxies are found in groups and clusters and a not uncommon occurrence is to have one galaxy interacting with another These interactions tend to change the morphology or shape of the galaxies involved rip out massive tidal tails of stars and gas and initiate star formation as the gas in the galaxies is compressed Galactic interactions take place over millions of years so this galactic dance cannot be observed in its entirety However observations of different interacting galaxies can be used to build up a sequence of how the interactions may have proceeded Supercomputer simulations can also be used to investigate how galaxies interact Complementary resource material for the Interacting Galaxies Investigation can be found at the UK Faulkes Telescope Observing Interacting Galaxies and Crashing Galaxies
11. SII N DSS2 Inez Figure 4 Aladdin Previewer Size and definition shows the image size File Edit Image Catalog Overlay Tool Help Install Gr ted Location IcRS g or DSS2 N POSSII x ee WV 246b ea N x Tz _ P a HA Simbad 7 LI Zoom 2 3x Ql cont 2 ts X l A pixe F r 5 N x r 4 HEN es 12 94 x 12 34 A 12 9 x 12 9 Haj pon ei S AA wat Search 4 as Figure 5 The Aladdin Applet Image size is shown at the bottom of the image Page 4 ASISTM Faulkes Telescope Deep Space in the Classroom http www astronomy mq edu au deepspace File Edit Image Catalog Overlay Tool Help Install amp GA Location 10 49 49 81 32 59 11 2 crs ts on DSS2 N POSSILy ae Fi gt lt a as a 3 y al T 7 a BN a wee A filter Ne rts hes ZA Simbad L L ee Bee N al cy Iw i i aA j td Zoom 2x 4 a sf lal t xF 1 RU 4 32 x 4 12 e D Elli grid multivi 12 9 x 12 9 Search amp EY Figure 6 Zoomed Aladdin Applet Measuring the sizes of the Galaxies This section can be quite mathematical so you might want to check before assigning this exercise to your students A way around this is to determine some of this for yourself in advance and give students some of these numbers 1 Open the image Open IRIS and Load the V
12. e Adjustment Here again it s a matter of playing with the controls until you achieve the look you want as in Figure 14 You may also want to play with the Gamma Adjustment Contrast adjustment and Saturation adjustment under this View menu There is no hard and fast rule about how to make the image look its best it really is a matter of you tweaking the controls It s best to be able to see your galaxies as you are making the adjustments You may also wish to refer to the Making a Colour Image teaching module for more information on other display options but before making further changes go to the next step to save your image 7 Save your colour image Once you are satisfied with your image and you are ready to save it select File Save This gives you multiple options for your save format If you want to use the coloured image in IRIS e g to make a mosaic out of several images then you need to select pic format see Figure 15 Otherwise you must save it in a format compatible with your other software e g tif jpg DO NOT save it as a FITS file or your work will be lost Page 10 lO x slaj Bleu slain al e Ji f 0 Range Auto Ready Figure 14 Adjusting the white balance is 0 x sjaj e l slal aj e Save As Save in Interacting Galaxies z a c File name
13. es 3 Determine the size of the galaxy in pixels Using the Pythagorean theorem these x y positions can be used to determine the apparent diameter of the galaxy in pixels Size in pixels sqrt 392 589 599 366 305 1 pixels 4 Determine the size of the galaxy in arcseconds Each pixel of the Faulkes Telescope images corresponds to a size of 0 27837 arcseconds This is set by the properties of the CCD camera and the focal length of the telescope Size in arcseconds 0 27837 arsec pixel 305 1 pixels 84 9 arcseconds 5 Find the distance to the galaxy in Megaparsecs Mpc Open the SIMBAD Database Query http simbad u strasbg fr simbad sim fid Type the name of the object into the Identifier section and select Submit ID as in Figure 2 This will return a page of basic data on that object as in Figure 9 Page 6 ASISTM Faulkes Telescope Deep Space in the Classroom http www astronomy mq edu au deepspace CDY SIMBAD query result D other query dentifier Coordinate Criteria Bibliography Script Output Help modes query query query query submission Object query ngc3395 C D S SIMBAD4 rel 1 084 2008 05 12CEST12 47 54 Available data Basic data Identifiers Plot amp images Bibliography Measurements External archives Notes Basic data VV 246b zal Interacting Galaxies query around with radius 2 arcmin Other object types G APG Ark CASG KUG LEDA 2MASX MCG UGC UZC Z M98c GIP KPG T76
14. etarium org resources ava category category G Gravitas Slow motion simulations of galaxy collisions of various types Information is provided on each of the simulations http www galaxydynamics org SIMBAD Astronomical Database Obtain data and images of galaxies http simbad u strasbg fr simbad The IRIS home page This page contains many tutorials and you can also download the IRIS User Manual http Awww astrosurf com buil us iris iris htm Page 12
15. ize in arcseconds 206265 arcseconds For NGC 3395 Distance to galaxy 23 3 Mpc calculated in Step 5 Size in arcseconds 84 9 arcseconds measured in Step 4 Size in Mpc 23 3 84 9 206265 0 0096 Mpc 9 600 pc 7 Convert parsecs into light years 1 parsec 3 26 light years Size of NGC 3395 in light years 31 000 light years You may wish to compare this with the size of the Milky Way which is 100 000 light years across Page 7 Making a Colour Image in IRIS Another activity you might like to undertake with your students is to create a colour image with your data Not only will you produce a stunning colour image you can use this exercise to teach students about what happens when different coloured light combines It can also be used depending on the data to show that stars and different regions of galaxies have different colours and lead on to a discussion of why this is so Note In order to do this you must have 3 images of the same object one taken through the B filter one through the V green filter and one through the R filter 1 Make sure your image filenames have the correct fit extension If not simply rename image fits to be image fit 2 Make sure your image filenames contain only lower case letters If your files have capitals in the filenames simply rename them using lower case letters 3 Start IRIS by double clicking on the program icon 4 Load and superimpose the images taken through
16. the B V and R filters Select View L RGB You need to put the filename drop the fit extension in the appropriate box and click OK x Red Ingo m Green ngc3395_v 4 gt Blue ngc3395_H Luminance fio Step 0 0 Red C Green Dx 10 0 Blue DY 10 0 r Apply Clear Ex s Figure 10 L RGB settings This will load and superimpose the images The screen will probably appear black initially and in order to see the resultant image more clearly click Auto in the Threshold window Note DO NOT at any point click on any of the four coloured buttons in this Threshold window Alternatively you might want to play with the sliding bars in the Threshold window to obtain a clear view of the objects in the image Note the Threshold window sets the brightness at which the pixels in the image are shown to be white in this case at a brightness of 32767 and the brightness at which the pixels in the image are shown to be black in this case a brightness of 0 Page 8 ASISTM Faulkes Telescope Deep Space in the Classroom http www astronomy mq edu au deepspace File View Geometry Preprocessing Processing Spectro Analysis DataBase Digitalphoto Video Help alfa B slal a e Figure 11 Stacked images E 1041 159 i1 Range Auto 4 Ready 48 bits X 280 Y 578 R 48 G 6 B 12 If you look closely at the stars rather than the galaxies in this s
17. uperimposed image you will be able to distinguish the image of the stars taken through the red filter red dots the image of the stars taken through the visual filter green dots and the image of the stars taken through the blue filter blue dots How much the telescope has moved between each image will determine how closely aligned the stars are at this stage You may also notice that the image itself has a general hue i e the background is not black in this case it has a reddish hue This will depend on how much light was let through each filter in this case the light coming through the red filter was stronger than that coming through the green or blue filters and may not be the case if you have previously selected Modified Equalization refer to the Making a Colour Image teaching module You now need to shift each of these individual images red green blue so that they line up on top of each other This process is quite subjective but you should be able to obtain a reasonable result 5 Line up the images L RGB x Select View L RGB Red ngc3395_r u Panel A indicates which image you are Green ngc3395_v 4 gt manipulating red green or blue Panel B is the controller where you move the Blue nge3395_b image The Step field in Panel C is where you indicate by how much you want the image to move at once Luminance a S Step do C Red Figure 12 Control panel ox foo C Green A C Blue 0 0
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