Homework answers / question archive / ASTR 10 Assignment #7 due Wednesday, May 5, 2021 Name: ______________________________ In this assignment, you will use information found mostly in Chapter 17 and 18 (and some things you’ve learned earlier) to determine the properties of a new star (or is it…?)

ASTR 10 Assignment #7 due Wednesday, May 5, 2021 Name: ______________________________ In this assignment, you will use information found mostly in Chapter 17 and 18 (and some things you’ve learned earlier) to determine the properties of a new star (or is it…?)

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ASTR 10 Assignment #7 due Wednesday, May 5, 2021 Name: ______________________________ In this assignment, you will use information found mostly in Chapter 17 and 18 (and some things you’ve learned earlier) to determine the properties of a new star (or is it…?). One night, you are at a party. You are talking to your friend about this great Astronomy class you are taking. You are about to tell your friend how cool your instructor is when someone interrupts: “You know about Astronomy? Come quick! I just found something bright in the sky that I’ve never seen before!” The object is not moving or flashing, so you know it is not an airplane. You notice that the object is near the North Celestial Pole. Right away, you say, “Well, it is probably not a planet or short period comet. Unless it is a long period comet, it is not in our Solar System.” “Wow! Really? Why not?” asks your friend. You respond: “Most Solar System objects orbit near a line across the sky called _______________.” You pull out your handy-dandy telescope that you bring to parties just in case this type of situation comes up. You quickly determine that it looks like a point of light, not a comet. “It’s probably not a long period comet, either” you tell everyone. Luckily, your spectrograph is still attached from the last time you used it. A quick observation shows the following spectrum: What is the approximate wavelength of peak brightness (in nanometers)? __________ nm You remember Wien’s Law and quickly look it up in your textbook (which you can bring everywhere since it is online). Assuming that the object behaves like a blackbody, what is its temperature (in Kelvin)? __________ K Now, assuming this object is a star, you remember the importance of the H-R diagram in determining the properties of stars. You quickly turn to Chapters 17 & 18 of your textbook. Based on its temperature, what is its spectral class? __________ For the next three questions, you assume that the object is a Main Sequence star. Give your answers in Solar units. In Solar units, the luminosity of the Sun is 1, the radius of the Sun is 1, and the mass of the Sun is 1. What is its approximate luminosity? __________L? What is its approximate radius? __________R? What is its approximate mass? __________M? (You may use either equations, charts, or tables found in the book or elsewhere for these questions.) “Wow! That’s a lot of stuff you can determine just from the temperature” says your friend. Upon further contemplation, you decide that since this object is bright and appeared suddenly (and because of its odd absorption lines), it is probably not a Main Sequence star. So you announce to everyone’s amazement “This object is probably a _______________!” [Hint: see Chapter 23] Extra Credit: After reporting the discovery to the International Astronomical Union’s (IAU’s): Central Bureau for Astronomical Telegrams (CBET), you decide that it may be a good idea to re-familiarize yourself with the positions of the stars and constellations. Below is a star chart for Wednesday, May 5, 2020, at 10:00 PM PDT. For extra credit, identify the Solar System objects shown. Also identify as many of the constellations shown on the chart as you can. You may use any print or electronic sources you want. The constellation outlines and boundaries are shown on the star chart below. Be sure to use the IAU designated official constellation names (Ursa Major) and not common names (“The Big Dipper”).