Download rasc2012(97)

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?