The star Sirius has a mass of 2.02 M Sun ; its companion star, the small astrono
ID: 154080 • Letter: T
Question
The star Sirius has a mass of 2.02 MSun; its companion star, the small astronomical body named Sirius B and only visible through large telescopes, has a mass of 0.978 MSun. What is the mass ratio of these stars?
2.02
1.98
2.07
0.484
2.998
0.5 points
QUESTION 2
Hydrogen has a prominent spectral line at 4186 Å, but when astronomers observe the line in the spectrum of a nearby star, what they observe is the following:
What is the Doppler shift of the hydrogen line in this star?
-69 Å
4117 Å
69 Å
-4117 Å
4186 Å
0.5 points
QUESTION 3
Hydrogen has a prominent spectral line at 4186 Å, but when astronomers observe the line in the spectrum of a nearby star,what they observe is the following:
What is the radial velocity of this star?
-69 Å
4117 Å
69 km/sec
-4117 km/sec
4186 km/sec
-4945 km/sec
-3970 km/sec
The velocity cannot be determined from this information.
0.5 points
QUESTION 4
A star whose motion is carrying it toward the Earth will appear:
Redshifted, with its velocity working out as a positive value
Blueshifted, with its velocity working out as a negative value
Redshifted, with its velocity working out as a negative value
Unshifted, with its velocity working out as a positive value
Blueshifted, with its velocity working out as a positive value
0.5 points
QUESTION 5
What is the definition of “rest wavelength,” which is usually denoted as 0 ?
The wavelength of a photon which is traveling toward an observer
The wavelength of a photon which is traveling away from an observer
The amount of energy a photon loses as it passes through a medium, like the glass lens of a telescope or detector
The wavelength of a spectral line measured from an unmoving light source
The amount by which a spectral line moves due to the motion of the emitting object
1 points
QUESTION 6
Two orbiting binary stars have a mass ratio of 3.11; if astronomers determine that the higher mass star has a maximum orbital velocity of 111 km/sec, what it the maximum orbital velocity of the smaller star?
3.11 km/sec
35.7 km/sec
111 km/sec
345 km/sec
Not enough information is given
1 points
QUESTION 7
The following three stars - the red star labeled Alpha, the green star labeled Beta, and the violet star labeled Gamma - are moving through space at a speed of 100 kilometers per second on trajectories heading generally in the direction of the Earth. Which of the three stars will show the greatest Doppler shift and which star will have the highest radial velocity?
They will all display the same Doppler shift and they will all show the same radial velocity
Star Alpha will display the greatest Doppler shift and star Gamma will show the largest radial velocity
Star Alpha will display the greatest Doppler shift and will also show the highest radial velocity
Star Beta will display the greatest Doppler shift and will also show the largest radial velocity
Star Beta will display the greatest Doppler shift but all stars will show the same radial velocity
Star Alpha will display the greatest Doppler shift but they will all show the same radial velocity
1 points
QUESTION 8
What is denoted by a negative velocity?
A very small velocity
The velocity of an object that is moving away from an observer
The velocity of an object that is moving toward an observer
Pure nonsense… velocities can’t be negative
The velocity of an object that is slowing down
1 points
QUESTION 9
In the picture below, star S is moving through space at a true speed of 177 km/sec along the path indicated by the arrow (making a 90 degree angle to the Earth). An astronomer observes the light from this star. What radial velocity will he measure?
177 km/sec
-177 km/sec
0 km/sec
A speed slightly less than 177 km/sec
A radial velocity slightly lower than -177 km/sec
1 points
QUESTION 10
An orbiting star which is part of a binary has a spectral rest wavelength of 4998 Å. An astronomer makes five measurements of the star at random times. On the first observation, the star’s spectral line is found at 5004 Å. At another time the spectral line is at 4998 Å. On a third reading the star’s spectral line is at 4996 Å. Shortly after that, the spectral line is measured at 4995 Å. Finally, after some time has passed, the spectral line is at 5002 Å. During which observation was the star likely moving directly toward the Earth with its highest velocity?
The observation that yielded a spectral line of 4995 Å
The observation that yielded a spectral line of 4996 Å
The observation that yielded a spectral line of 4998 Å
The observation that yielded a spectral line of 5002 Å
The observation that yielded a spectral line of 5004 Å
1 points
QUESTION 11
In the picture below the orbits of two binary stars are pictured. The direction of orbit of one star (in green) is shown (the orange star is not shown). In which position will the star’s spectral line’s measured shift (obs) be the same as its rest wavelength (0)
Position A
Position B
Position C
Position D
Positions A and C
Positions B and D
Positions A, B, C, and D
1 points
QUESTION 12
In the picture below the orbits of two binary stars are pictured. The direction of orbit of one star (in green) is shown (the orange star is not shown). Which of the following statements about the binary star system is true?
The green star is moving toward the Earth at all points between positions C through D to A. The orange star would be moving away from Earth during this time.
The green star is moving away from the Earth at positions C through D to A. The orange star is also moving away from the Earth during this time period.
The green star is moving away from the Earth at positions C through D and then toward the Earth from D through A.The orange star must be moving away from the Earth at positions C through D also and then toward the Earth during the D through A time period.
The green star is moving toward the Earth at positions C through D to A. The orange star's motion during this time cannot be said with any certainty, however.
The green star is displaying its greatest redshift at position A and greatest blueshift at position C. The orange star will also display its greatest redshift at the time of position A and its greatest blueshift at the time of position C.
The green star displays no radial velocity at point D or point B. These are the same instants in time that the orange star would show no radial velocity as well.
The green star is moving away from the Earth at points D through A and then toward the Earth at points A through B.The orange star, by contrast, will be moving toward the Earth at the times of position D through A and away from away from the Earth at the time of positions A through B.
2 points
QUESTION 13
A pair of binary stars orbit one another. One star displays a maximum redshift of +285 km/sec and a maximum blueshift of -285 km/sec. Its companion shots a maximum blueshift of -23 km/sec and a maximum redshift of +23 km/sec. How many times heavier is the large star than the smaller star?
0.081
262
-0.0807
12.4
0.13
More information about the stars is needed
1 points
QUESTION 14
A star is part of a single-lined spectrum, meaning you only see one set of spectral lines from one dominant star outshining its smaller, dimmer companion star. A prominent spectral line from the dominant star normally falls at 4812Å but the motion of the star in its orbit causes the position to shift. The astronomers makes a data table of observed wavelengths (below). On which day is the star moving directly toward the Earth in its orbit?
February 19th
February 21st
February 24th and 26th
February 25th
It cannot be determined from the values given
2 points
QUESTION 15
A star is part of a single-lined spectrum, meaning you only see one set of spectral lines from one dominant star outshining its smaller, dimmer companion star. A prominent spectral line from the dominant star normally falls at 4812Å but the motion of the star in its orbit causes the position to shift. The astronomers makes a data table of observed wavelengths (below). What is the radial velocity of this star on February 25th?
6 km/sec, heading toward the Earth
-374 km/sec, heading toward the Earth
0 km/sec
6 km/sec, heading away from the Earth
374 km/sec, heading away from the Earth
2 points
2.02
1.98
2.07
0.484
2.998
Explanation / Answer
1) The star Sirius has a mass of 2.02 MSun; its companion star, the small astronomical body named Sirius B and only visible through large telescopes, has a mass of 0.978 MSun. What is the mass ratio of these stars?
Solution :Mass ratio of these stars = 2.02 / 0.978
= 2.06544
= 2.07 ( After rounding)
Related Questions
drjack9650@gmail.com
Navigate
Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.