January's Featured Variable: Star Finder Chart for Pleione Pleione in the Pleiades

I bet you have seen a star twinkling —the air It is easy to estimate the brightness surrounding Earth affects starlight, making it ("magnitude") of a star, but first note: look like the star is sparkling! Even if we • in finder charts like below, brighter traveled outside our atmosphere, we could stars are indicated by larger dots still see many stars change brightness. • the brighter the star, the lower the Some stars dim, brighten, dim again, and so magnitude number on…in under a second! Others do so over • magnitudes are written to the nearest years. These are “variable stars.” tenth—but without a decimal point, which could be confused as a star. So, to enable anyone, anywhere, to If you live in the northern hemisphere, a 41= magnitude 4.1 participate in scientific discovery variable star YOU can see this month is • in this chart, magnitudes for through variable star astronomy Pleione, in a bright star cluster of the comparison stars—stars of a similar constellation Taurus, "The Bull." This cluster, brightness (in this case, to Pleione)—are American Association of Variable Star Observers "the Pleiades," looks like a tiny spoon. noted 49 Bay State Road, Cambridge, MA 02138, USA Telephone: +1 (617) 354-0484 Pleione is the dimmer of the two stars in the Find two comparison stars close to your given www.aavso.org | [email protected] spoon's "handle." Compare Pleione to other variable star's brightness—one brighter and stars, especially Taygeta and Celaeno at the one dimmer. Then observe—is the variable's spoon's opposite end. Looking closely, you brightness half-way between the two should see it at a different brightness from comparisons'? A quarter? Really close? Apply night to night. Binoculars make it a lot easier! that fraction to the difference in the two magnitudes and you estimated the star's Pleione rotates once in under 12 hours, so brightness for that time! fast that some of the star is forced outward, This star comparison and finder chart for forming a disk around the star. Interactions Pleione will help you estimate its brightness. between the star and the disk cause minor changes in the star’s brightness. With practice, you could detect these changes!

Time Magnitude ______AAVSO can help YOU become a About the AAVSO Connect with the AAVSO citizen astronomer!

The American Association of Variable Star Who are AAVSO Members? Discover the benefits of membership and Observers (AAVSO) is an international join us! nonprofit organization of citizen and A citizen scientist—contributes to science professional astronomers interested in stars by acquiring data on variable objects and https://www.aavso.org/join-aavso#benefits that change in brightness—variable stars. submitting them to our databases, or other activities, such as data mining. Benefits include being able to participate in From its earliest days in 1911, AAVSO An educator or mentor—teaches our mentor program: beginners are paired members have included some of the most observing skills to fellow AAVSO observers, with an experienced observer for guidance prolific astronomers of the 20th & 21st through instructing AAVSO CHOICE courses and techniques: centuries. or being a mentor. https://www.aavso.org/mentor-program

AAVSO Databases A student—is learning how to find a star, * * * * * set up a telescope, observe, submit data, or AAVSO International Database (AID): The is increasing their astronomy knowledge AAVSO Tools for Beginner Observers: largest and most comprehensive digital variable star database in the world, with over A professional astronomer— uses AAVSO Beginner Tutorials: aimed at those with 43 million variable star observations—a free data and services to advance their research absolutely no experience, these introduce resource for the entire scientific community An AAVSO Ambassador—a student or variable star science basics and then provide Variable Star Index (VSX): a collection of up- young professional representing AAVSO "challenges" for you to apply the concepts: to-the-minute data on over 200,000,000 through astronomy education and activities https://www.aavso.org/tutorials specific variable stars Interested in becoming an ambassador? • www.aavso.org/ambassador-program AAVSO Online Forum: talk to peers for Spectroscopy Database: spectroscopic • Email [email protected] advice: https://www.aavso.org/forum observations of stars * * * * * Solar Database: Sudden Ionospheric Observing Manuals: each one is dedicated Disturbance (SID) Database, and data relating You, your friends, and colleagues are also to a type of observing, including visual, CCD, to sunspot observations invited to join us for: DSLR, Spectroscopy, Solar, and more: https://www.aavso.org/observing-manuals Exoplanet Database: long-term follow-up AAVSO's free-to-all 2021 Webinar Series! information on planets orbiting other stars Come to one or all! Most Saturdays of the year. CHOICE Courses: peer-taught informal See the schedule and sign up: online observing courses: https://www.aavso.org/2021-webinars https://www.aavso.org/choice-astronomy

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