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Northern Prairie Star Party Black Nugget Lake September 15, 2012 Brian Martin The King’s University College Three Fundamental “Sciences” • Measuring “Distance”, Position & “Scale” Astrometry • Measuring Brightness and Intensity Photometry • Measuring “Colour” Spectroscopy Exciting science that you can do from the back yard! Astrometry How big are the lunar features in this image? August 29, 2012 H-alpha filter 0.001 s exposure ED80 Atik 314L+ camera TKUCO Some Math … R S q * The Small Angle Formula Rq = S where: • R = distance from object • q = angle that the object subtends in the sky • S = distance across the object * Angle in radians The Scale of Your Telescope • Scale in (seconds of arc)/mm found by: 206,265 scale focal length • In the previous image a ED80 telescope was used so the scale is (206265)/(600 mm) = 343.8 “/mm • The Atik 314L+ has 6.45 mm pixels, so each pixel has a scale of 342.8”/mm × 0.00645mm/px = 2.22 “/px when used with the ED80 • By measuring the number of pixels you can measure the angle that an object or feature subtends s rq s (0.002524 AU)(149 598 000 km/AU) 2.2 "/ px 206265" Distance = 0.002524 AU s 4.027 km / px 304 px = 1236 km 850 px = 3457 km (0.5% error) Some other images… • Capuanus Crater: – – – – – – December 26,2009 C14, f/11 Imaging source DMK2104 2000 frames Distance = 0.002523 AU Scale = 0.20”/px = 0.37 km/px • Apennines (Eratsothenes, Archimedes) – – – – – – March 1, 2012 C14, f/7 Atik 314L+ 20 frames (0.005 s) Scale = 0.52”/px Distance = 0.00262 AU • Jupiter – – – – – – November 5, 2011 Distance = 3.98101 AU C14, f/11 Imaging Source DMK2104 LRGB (~2000 frames each) Scale = 0.29”/px = 837 km/px 159 px = 133 000 km 170 px = 142 000 km Oblateness = (142 -133)/142 = 6.3% • M57 – – – – – – August 26, 2011 C14 f/7 ST7E LRGB Distance = 2300 ly Scale 1.49”/px = 0.017 ly/px 160 px = 2.7 ly • M15 – – – – – – August 21, 2011 C14 f/7 ST7E LRGB Distance = 33 Kly Scale 1.49”/px = 0.238 ly/px 534 px = 127 ly Photometry – Measuring Changes in Brightness • Intrinsic Variables – d Scuti – SX Phe • Novae and Supernovae • Cataclysmic Variables Consumer grade CCD cameras… • • • • • • Capable of doing excellent science! Modest cost (< $2000) Excellent software support Monochrome with no anti-blooming is preferred Pixel size should be carefully matched to image scale – need to oversample Capable of milli-magnitude precision photometry Atik 314L+ SBIG ST7E SX Phoenicis Variables • BL Camelopardalis – Average mag 13.1 – Period • 0.0389d • 56 minutes – this is an exciting system to watch!! 40 s integration, C14 f/7 ST7E camera – KAF400 detector The Light-Curve… BL Cam Teff 7730 K Age ~4Ga Metal poor Period shows a Small change over time! November 9, 2009 November 9, 2009, s (C2-C1) = 0.007 mag DY Pegasi … A Nice Intro to SX Phe • A great star! – Bright (m = 10.3) – Excellent Check and Comparison stars – Well placed for fall observations Data collected with 8” Newtonian and SpectraSource Lynxx (TC211) Cataclysmic Variable Stars • Binary stars that are exchanging mass • One of the stars is compact • Hot spot forms on accetion disk • Accretion disk around compact star produces variability • A rewarding study for amateurs! Two exemplar CVs… • DW Uma – Period (d) 0.136606 – Mag 14 - 18 TKUCO 120 s image 0.32 f/4.8 • GK Persei – Period (d) 1.996803 d – Mag 11.5 - ? TKUCO 60 s image 0.32 f/4.8 Other Photometric Delights! • Novae and Supernovae • Algol systems • Asteroids NGC 6946 30s exposure September 29, 2004 SN 2004ET 0.32 f/4.8 Newtonian ST7E camera Spectroscopy • Broad and Narrow band filter imaging • Low Resolution Spectroscopy • Medium – High Resolution Spectroscopy Broadband Colour Imaging L R M27 LRGB, August 2011, C14 f/7 ST7E G B Narrow Band Imaging • • • • Ha Hb SII OIII Ha S II O III C14 f/7 Atik 314L+ March 1, 2012 LRGB image of central region of M51 C14 f/7 ST7E L filter with Ha overlay showing star forming regions along spiral arms C14 f/7 Atik 314L+ Stellar Spectra (Low R) • Remarkably easy to do – even with modest equipment! – Small telescope w/wo tracking – CCD or DSLR – Rainbow Optics or Star Analyzer grating • Introduces a fascinating new direction for amateurs Some samples… (trailed images with Atik 314L+, Orion 80 mm ED) Note Deneb’s narrow lines! Vega, Teff = 9600 K Altair, Teff = 6900 K – 8500 K Ca II line Altair is a very fast rotator and is squished like a football! Hotter at the poles by about 20% Other Interesting Stars… Which is these is the hottest star? T = 7 100 K F2 T = 31 000 K B0.5e T = 8 400 K A5 Be Star with disk Planetary Nebulae The “Eskimo” – NGC 2392 C14 f/7 10 minutes April 21, 2011 The reason nebula filters work! Measuring the Expansion of the Universe! Rest Frame (A) Measured (A) Dl (A) z Hb 4860 5666 806 0.166 Ha 6563 7562 990 0.151 z Dl 3C273 C14 f/7 60 minutes ST7E April 5, 2011 l Zaverage = 0.159 Universal Expansion • What does z = 0.159 mean? – – – – Apparent recessional velocity is 0.159C = 47 700 km/s! Hubble expansion law: v HR Hubble’s constant H = 70 km/s/Mpc R = 681 Mpc = 2.2 billion light years! Medium/High Resolution Spectroscopy • For more advanced work • Requires robust mount and tracking • Need as much aperture as possible • BUT – still well within the reach of advanced amateurs and astronomy clubs! The L200 Littrow Configuration • Can resolve to about 1 A (R = 3000) • Built from a kit, cost ~$1000 • Capable of useful research on Be, WR and Algol type stars (and much more!) The Solar Spectrum ST7E on C14 Altair Homebrew for under $200! And it Works! The Magnesium Triplet… R > 5000! Some References… • Christian Buil http://www.astrosurf.com/buil/ • Tom Field - RealTimeSpectroscopy (RSPEC) http://www.rspec-astro.com • Rainbow Optics Spectroscopes http://www.starspectroscope.com/ • Center for Backyard Astrophysics (CBA) http://cbastro.org/ Thank you – Questions?