April's Featured Variable: Star Finder Chart for R Leonis R Leonis in Leo the Lion
I bet you have seen a star twinkling —the air It is easy to estimate the brightness surrounding Earth makes it look like the star ("magnitude") of a star, but first note: is sparkling! Even if we went to outer space, • in finder charts like below, brighter stars we could see many stars change brightness. are indicated by larger dots “Variable stars" continuously dim, brighten, • the brighter the star, the lower the and dim. Some complete the pattern in magnitude number under a second, while others take years. • magnitudes are written to the nearest tenth—but without a decimal point, to enable anyone, anywhere, to One variable star YOU can see this month is R which could be confused as a star. So, participate in scientific discovery Leonis in the constellation Leo the Lion. It 47= magnitude 4.7 through variable star astronomy was only the fourth long period variable • in this chart, magnitudes for comparison discovered. Make your discovery of this star stars—nearby stars to compare a given by looking 5 degrees (about one binocular American Association of Variable Star Observers star's brightness to—are noted field) west of the bright star Regulus (Alpha 49 Bay State Road, Cambridge, MA 02138, USA Leonis), the heart of this constellation. R Find two comparison stars close to your Telephone: +1 (617) 354-0484 Leonis appears scarlet and forms a small given variable star's brightness—one www.aavso.org | [email protected] triangle with two yellow stars. brighter and one dimmer. Then observe—is the variable's brightness half-way between R Leonis is a red giant star near the end of its the two comparisons'? A quarter? Really life. Its low surface gravity means its outer close? Apply that fraction to the difference in atmosphere is loosely bound, forming a shell the two magnitudes and you estimated the around its core. Pulsations within the core star's brightness for that time! may send shock waves through this shell, This star comparison and finder chart for R causing variation in brightness (which Leonis will help you estimate its brightness. changes over about 310 days). This may happen to our Sun in 5 billion years. The icon indicates the location of R Leonis. When dim, R Leonis is difficult to see, even in binoculars, so look for the “missing” star of the typical star pattern. The star is still there, we just can’t see it!
Time Magnitude ______AAVSO can help YOU About the AAVSO Connect with the AAVSO become a 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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