Stars that vary

Variable Stars

(The featured image and others unless otherwise noted are from the AAVSO.)

Today we have nine questions, so we will take ten minutes to complete the challenge.

Please get out a clean sheet of paper and a No. 2 pencil and prepare for today’s Astronomy Challenge.

If you find a mistake, please let me know. Do your best.

The topic today: variable stars

You have ten minutes to complete the challenge. Begin now.


  1. What do astronomers call stars whose brightness changes?

  1. Variable stars can be divided into two man classes: those where variability is due to interaction with another star or two (extrinsic) and…..WHAT?

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  1. What kind of intrinsically variable star does not have hydrostatic equilibrium, a balance between gravity pulling n and pressure pushing out?

  1. What kind of pulsating variable star led Edwin Hubble to understand that galaxies are outside the Milky Way Galaxy?

5.  Name the variable star:

a.  discovered by David Fabricius in 1596 ,Screen Shot 2018-12-12 at 5.55.25 PM

b.  spectral type G star,

c.  with a mag   9.3 to 3.4,

d.  330 day period, making it a Long Period Variable,

e.  whose name is Arabic for “wonderful”

f.  also known as omicron Ceti:

6.  Name the variable star:

a.  Known to the ancients (Hebrews, Chinese)

b.  spectral type star B8 V white star,

c.  drops from 2nd magnitude to 3rd

d.  period of 2 days 20 hours and 48 minutes,

e.  whose name is Arabic means “demon’s head”

f.  also known as “Beta Perseus”

7.  Name the variable star:

a.  discovered by John Goodricke, a teenager, in 1784 ,

b.  spectral type star, semi-detached variable

c.  drops from mag 3,34 to 4.34

d.  in 12.9 days,

e.  whose name is Arabic means “the tortoise”

f.  also known as “Beta Lyrae”

8.  Name the variable star:

a.  Also discovered by John Goodricke in 1784 ,

b.  spectral type star F5 Ibv, short term pulsating star

c.  bright as 3.5 and fades to 4.4

cycle every 5.4 days

Screen Shot 2018-12-12 at 5.54.54 PM.png

  1. What is the name (short, abbreviated version is acceptable) of the organization that collects and shares observations and data about variable stars?

OK, pencils down. Let’s trade with a neighbor and check one another. Here are the correct answers and your “neighbor” who got the correct answer on my Periscope broadcast on December 10, from 8:00 am (eastern US) to 9:00.

Help Make the World a Better Place!

On my Periscope broadcast any player who is the first to give the correct answer to a question is a winner. Winners who make a contribution to one of my charities in the next 30 days will have their gift matched by me up to $100. My charities are listed on my blog.     Tell the charity to contact me about your contribution.

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Link here to my blog “An Island in the Sea of Mystery.”

You are welcome to play with us during the next live broadcast of

“Let’s talk astronomy” this coming Monday beginning at 8 am eastern US time on Periscope.

Periscope is a live video streaming app for Android and iOS available in the App Store.

On Monday, December 10, 2018, our Periscope Trivia Contest was about variable stars.

The questions are given above, the correct answers and the winners are given below.

Correct Answers……..Periscope Winners:

  1. variable stars………. @Pircano.   A few of us over the centuries have notice stars that change brightness. Only in the last 500 years had the study become systematic.

  1. intrinsic: variability due to changes of a single star………… @jacob48642: Some variable stars are being affected by another star. These are considered extrinsic variables and include eclipsing binaries. Pulsating variables and cataclysmic variables are considered “intrinsic.”

  1. pulsating variables…….. @Pircano There are different types of pulsating variable stars.   The length of the period is one discerning factor, for example, Cepheids have periods of between 1 and 70 days. Some, like RV Tauri, are distinct because of the shape of the light curve. And others are classified by amplitude like Mira in question #5.

  1. Cepheids……….@Pircano  Henrietta Leavitt had discovered the period-luminosity relationship of this type of variable. Edwin Hubble used that relationship to determine that the Milky Way Galaxy os not the totality of the universe.

  1. Mira….………@speear40 Our live contestant got the right answer with clue “d.” How many clues did you need?

  1. Allgol …………..@speear40.  This challenge was also answered after

    Algol, by Dennis Hands,           Exposure 0.5 sec December 5, 2018

    clue “d.

  1. Shilyak…………@Pircano John Goodricke was a teenager when he discovered this star is variable.

  1. Delta Cepheid…………..@no one got this Challenge question.  This star is the model for Cepheid variables.

  1. AAVSO…………..@speear40: Learn more about this organization at

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Thanks goes out to all participants, and Congratulations to everyone who got one right.

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