Cosmic Distance Ladder

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Cosmic Distance Ladder
Cosmic Distance Ladder
Cosmic Distance Ladder
Cosmic Distance Ladder
DSS 1 Image
ASTR 8400 Fall 2007
Ben Team
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Outline

• Specifications of RR Lyra
• Historical Background
• Basis for Methodology
• Analysis of Methodology
• Bibliography
• Light-Curve Modulation (Time Permitting)

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RR Lyrae
AKA

• V RR Lyr
• SAO 48421
• GSC 03142-00494
• HD 182989
• HIP 95497
• 2MASS J192527934247040
• TYC 3142-494-1

2MASS K band image
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RR Lyrae

• RA 19 25 27.913
• Dec 42 47 03.70

• Spectral Type F5
• Parallax 4.38 mas
• Teff 6222 K
• Log(g) 2.80
• VRadial -72.4 km s-1
• B 7.29
• V 7.13
• J 6.949 0.019
• H 6.693 0.023
• K 6.648 0.017
• Fe/H solar -1.39

http//simbad.u-strasbg.fr
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Historical Information

• Discovered by W. Fleming 13 July 1899 on a
  multiple exposure plate
• By 1902 P0.5668d and dm 0.83

Kiess, 1913
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RR Lyra Light Curve
Martin Plummer, 1915
Smith et al., 2003
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HST Observations of RR Lyra
Benedict 2002
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RR Lyrae Type Stars

• Population II elder Stars
• Instability-Strip Variables
• Horizontal Branch
• Period lt 1 day
• All have similar time-averaged luminosity
• Radial Pulsations in Fundamental and/or First
  Overtone mode

Chaission McMillan
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Equations
Binney Merrifield, 1998
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The Distance to RR Lyra
Popowski Gould, 1998
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How Well Does It Work?

• R0 - Distance to galactic center
• Weighted AverageR0 8.0 /- 0.5 kpc

Reid, 1993
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How Long is the Ladder?

• Target
• F5, MV 0.54, P 3.6 hr
• Detector HST ACS
• LMV(SNR10, t6500s) 28 http//www.stsci.edu/hst
  /wfpc2/wfpc2_acs.html

Dmax (BoE Calc)
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Bibliography

• Benedict et al, 2002, The Astronomical Journal,
  Volume 123, Issue 1, pp. 473-484
• Binney, J. Merrifield, M., 1998, Galactic
  Astronomy, Princeton University Press
• Blazhko, 1907, AN, 175, 325
• Bono, G. 2003, Stellar Candles for the
  Extragalactic Distance Scale, ed., D. Alloin W.
  Gieren ( Berlin Springer)
• Carroll, B. Ostlie, D., 1996, An Introduction
  to Modern Astrophysics, Addison-Wesley Publishing
  Co., Inc.
• Gould, A. Popowski, P. , 1998, ApJ, 506,
  844-853
• Kiess, C. C., 1913, LOB, Vol VII, No. 232
• Martin, C. Plummer, H., 1915, MNRAS, Vol. 75,
  p.566
• Popowski, P. Gould, A. , 1998, ApJ, 506,
  259-270
• Popowski, P. Gould, A. , 1998, ApJ, 506,
  271-280
• Popowski, P. Gould, A. , arXivastro-ph/9808006
  
• Reid, M., 1993, ARAA,Vol. 31 (A94-12726 02-90),
  p. 345-372
• Shu, Frank, 1982, The Physical Universe, An
  Introduction to Astronomy, University Science
  Books
• Smith, H. et al., 2003, PASP, 115, 43-48
• van Albada, T. Baker, N., 1971, ApJ, 169,
  311-326
• http//www.aavso.org/

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Blazhko Effect
Sergei Nikolaevich Blazhko (1870 - 1956)

• Blazhko (1907) published data on variable star
  periods which show longer period oscillations
• Prager (1916) Shapley(1916) both notice longer
  period oscillatory modulations
• No consensus on cause currently

NAS Biographical Memoirs, 1932
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Blazhko Effect Characteristics

• RR Lyr Period 41 days
• Bailey type ab
• 20 30 exhibit Blazhko modulations
• 11-533 days typical
• Bailey type c
• a few exhibit similar phenomenon
• Amplitude varies
• RR Lyr shows 4 yr cycle with 90o phase shift