Although it may not be obvious at first sight, many stars vary in brightness over time. Some of these variable stars change magnitude on predictable timescales, others are s regular. Recording the variations is a rewarding and straightforward form of observing which ultimately helps decode how certain stars work. In this article we'll look at different types of variable, how to observe them and how to interpret the results. We'll also give you some examples to get you started.
A star's brightness is quantified by its magnitude. Some stars remain at constant magnitude, some vary a little and some vary a lot. Indeed, some stars become bright enough to change the visual appearance of their host constellation, such as Betelgeuse (Alpha (a) Orionis) and Mira (Omicron (o) Ceti) (see 'Six variable stars to get you started' on page 66). Variability can occur on a predictable basis or can be highly irregular. The majority of variable stars appear to vary indefinitely, but some vary just once, with extreme examples being supernovae.
Variation in magnitude is either caused by external factors or by internal changes within the star; those in the first group are known as extrinsic variables, while those in the second are called intrinsic variables. An eclipsing binary such as Algol (Beta (B) Persei) is an example of an extrinsic variable; its observed brightness variation is due to a dimmer star passing in front of a brighter one with a very predictable period.
This story is from the {{IssueName}} edition of {{MagazineName}}.
Start your 7-day Magzter GOLD free trial to access thousands of curated premium stories, and 9,000+ magazines and newspapers.
Already a subscriber ? Sign In
This story is from the {{IssueName}} edition of {{MagazineName}}.
Start your 7-day Magzter GOLD free trial to access thousands of curated premium stories, and 9,000+ magazines and newspapers.
Already a subscriber? Sign In
Could We Find Aliens by Looking for Their Solar Panels?- Designed to reflect ultraviolet and infrared, the panels have a unique fingerprint
Researchers searching for life beyond Earth spend a lot of time thinking about what telltale signs might be detectable astronomically. Forms of unambiguous evidence for the presence of life on another world are known as biosignatures. By extension, techno signatures are indicators of activity by intelligent, civilisation-building life.
Antimatter- In our continuing series, Govert Schilling looks at antimatter, the strange counterpart to most of the matter filling our Universe
Particles and corresponding antiparticles are very much alike, except they have opposite electrical charges. For instance, the antiparticle of the electron - known as the positron - has the same tiny mass, but while electrons carry a negative electrical charge, positrons are positively charged.
Where Have All The Milky Way's Early Stars Gone?- Our Galaxy has a curious lack of pristine stars
The Big Bang produced a Universe filled almost exclusively with hydrogen and helium; all other elements - what astronomers call metals - were produced by stars, supernovae and everything that happens later. So if you can pick out a pristine star with no metals polluting it from among the billions in the Milky Way, then you are likely to have a star dating from our Galaxy's earliest days.
Inside The Sky At Night - Two years ago, exoplanet scientist Hannah Wakeford received some of the first data from the JWST
Two years ago, exoplanet scientist Hannah Wakeford received some of the first data from the JWST. In July's Sky at Night, we discovered what she's learned since then.
How to stack DSLR data in Siril
Easily combine multiple frames to boost detailin your astro photos
Lunar occultation of Saturn
You'll need to strike a balance on 21 August to capture the Moon covering the ringed planet
How to plot a variable star light curve
A rewarding project to chart stars that change brightness
Smartphone photography with a telescope
Mary Mcintyre explains how to get impressive night-sky images using your phone
Once-a-century solar storm is overdue
If a Carrington Event struck today it would be catastrophic, says Minna Palmroth
The new era of human spaceflight
There's been a step-change in crewed space missions since the dawn of the 21st century. Ben Evans charts its course and looks ahead to future horizons
