Products
Rewards 
from HOLOOLY

We are determined to provide the latest solutions related to all subjects FREE of charge!

Please sign up to our reward program to support us in return and take advantage of the incredible listed offers.

Enjoy Limited offers, deals & Discounts by signing up to Holooly Rewards Program

HOLOOLY 
BUSINESS MANAGER

Advertise your business, and reach millions of students around the world.

HOLOOLY 
TABLES

All the data tables that you may search for.

HOLOOLY 
ARABIA

For Arabic Users, find a teacher/tutor in your City or country in the Middle East.

HOLOOLY 
TEXTBOOKS

Find the Source, Textbook, Solution Manual that you are looking for in 1 click.

HOLOOLY 
HELP DESK

Need Help? We got you covered.

Chapter 16

Q. 16.1

Astronomers use a measure of distance called the parsec, abbreviated pc, more often than the lightyear, another measure of distance. A star that is one parsec away has a parallax of one second of arc relative to the Earth’s orbit about the sun. (Parallax is the apparent displacement of a body due to its observation from two different positions.) One parsec is about 3.26 lightyears. Determine Hubble’s constant in km/s per Mpc.

Strategy We need to use conversions and the value of the Hubble constant. One Mpc is a megaparsec or 10^{6} pc.

Step-by-Step

Verified Solution

We use the value just given for Hubble’s constant, 22 km/s per million lightyears, and make the conversion to Mpc.

 

\frac{22 km / s }{\text { million ly }} \frac{3.26 ly }{ pc }=72 \frac{ km / s }{ Mpc }

 

Hubble’s constant is quoted using either unit. Different measurements yield values between 68 and 75 km \cdot s ^{-1} \cdot Mpc ^{-1}. The best current estimate using all measurements is 71 km \cdot s ^{-1} \cdot Mpc ^{-1}, a value that we will use from now on in this text.