Question

1500 1000 500 5 10 15 20 Distance (Mpc) Figure 7.6: A Hubble diagram showing the relationship between galaxy distance and re- cessional velocity, where distances were derived from the period-luminosity relationship for Cepheid variable stars identified within each galaxy. The M100 point is circled in red, and based in part on the data shown in Figures 17.4 and 7.5. The slope of the relationship is 79 +4 km sec1 per Mpc, and the correlation coefficient R is 78 % , indicating that there is a strong positive relationship between velocity and distance. 6. Using Figure 7.6 above, is the M100 galaxy (circled in red) one of the most nearby or distant galaxies for which Cepheid- derived distances are shown? Velocity (km sec-) 6. Using Figure 7.6 above, is the M100 galaxy (circled in red) one of the most nearby or distant galaxies for which Cepheid-derived distances are shown? 7. What is the recessional velocity for a galaxy lying 10 Mpc away from us? 8. What relationship do you see between the data points and the best fit line on the Hubble Diagram in Figure 7.6? 9. What is the Ho (Hubble's constant) in Figure 7.6? What is the current acceptable value of this constant? (see pages 3 and 4 on the lab PDF for help here) Draw a Conclusion: 10. Discuss the significance of Hubble's work. Summarize how Hubble Diagrams are constructed and what astronomical data they demonstrate.

Answer 1

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the given data For ghe slop of dacta is 79t4) kn/sa/Mpc Which is Notolng but the Hubble' consteut Naelf Hence He C1924) Knlec/Mpc aeseptoble value of Hubble's constaut Qo KMlsee/Mpe Th cunct is Pepareds object direethy proportfionel to the is The recesion distemce of t velouty of qalaries from rechhit Hubble calculated dhe technique. The yed Ahitt pom elechomegretic wor mean uec ed hem objat. alumng expanaien Yacyation tr in 1929 Hubble estimaded e volu of Ho to be about /Mpc 500 Km/SCe ort differeut Cealaxies data, Some the He demonibated tthe fna bunch of Se.T bunch of Gatoxycclw kr alaxies ar Cluster of Croloxy Aas same velocity bounded temselves. Scatfer ing of clata is dlue to he Bome addition al yeardueal mstion, not pur expontjan. and later he ghonn the

The value of the Hubble parameter is not certain today however the most acceptable value is 80-90 km/sec/Mpc.