Full Answer
What are some interesting facts about the star Algol?
Star Facts: Algol. The Algol system is not only the first, and perhaps the best known, eclipsing binary system to be discovered, it is also among the first non-nova variable stars to be found, and today it serves as the prototype for the Algol-class of variable stars. While the variability of the primary star in the system is well-known,...
How bright is Algol during an eclipse?
During an eclipse, you can compare the brightness of Algol to the stars Almach (magnitude 2.1) and Epsilon Persei (magnitude 2.9). But unlike many binary stars, the orbital plane of Algol is aligned to our point of view, which means the fainter cool star partly blocks the brighter hot star once per revolution.
What is the magnitude of ALGOL?
Magnitudes are celestial numbers that measures how bright a sky object is; the smaller the value, the brighter the object. Most of the time, Algol is a bright as Gamma Andromedae, whose magnitude is +2.1. This magnitude is bright enough to be seen even through severe light pollution.
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Is Algol bigger than the Sun?
Our sun is 93 million miles from Earth, so the distance between Algol A and Algol B is just 5 percent of the distance between the Earth and the sun. Algol A is the primary star in the system and is 3.7 times more massive than the sun.
How old is the Algol star?
With a surface temperature of 13,000 K, it is 182 times more luminous than the Sun. The star spins considerably faster than the Sun, with a projected rotational velocity of 49 km/s. Its estimated age is 570 million years.
How many stars does the Algol system have?
three-starAlgol is a three-star system, consisting of Beta Persei Aa1, Aa2, and Ab – in which the hot luminous primary β Persei Aa1 and the larger, but cooler and fainter, β Persei Aa2 regularly pass in front of each other, causing eclipses.
Why is Algol the Demon Star?
Bottom line: Algol has the nickname the Demon Star because it represents the head of Medusa. This variable star probably intrigued the ancients with its inconstant behavior.
Which star has hottest core?
The hottest one measures ~210,000 K; the hottest known star. The Wolf-Rayet star WR 102 is the hottest star known, at 210,000 K.
Is there a Medusa constellation?
In the 19th century, the constellation was known as Perseus et Caput Medusae (Perseus and the Head of Medusa). Today, it's called Perseus the Hero or simply Perseus (Per.), and is one of 88 constellations recognized by the International Astronomical Union.
What does Algol stand for?
Algorithmic LanguageALGOL (/ˈælɡɒl, -ɡɔːl/; short for "Algorithmic Language") is a family of imperative computer programming languages originally developed in 1958.
How far is the Algol star from Earth?
92.95 light yearsAlgol / Distance to EarthAlgol is 92.8 light years from Earth; however, about 7.3 million years ago it passed within 9.8 light years and its apparent magnitude was approximately −2.5, considerably brighter than Sirius is today.
What was Algol used for?
Formerly known as IAL, ALGOL is short for algorithmic language. It is a family of portable programming languages for scientific computations that had a strong influence on other languages. Additionally, ALGOL was used as the standard method for creating algorithms by the ACM in textbooks and academia for over 30 years.
What happens when a star is blinking?
In simple terms, twinkling of stars is caused by the passing of light through different layers of a turbulent atmosphere. Most scintillation effects are caused by anomalous atmospheric refraction caused by small-scale fluctuations in air density usually related to temperature gradients.
Is Rigel brighter than Betelgeuse?
The "beta" designation is commonly given to the second-brightest star in each constellation, but Rigel is almost always brighter than α Orionis (Betelgeuse).
Is Algol a white dwarf?
Details. The Twin Star Algol is a binary system consisting of a massive Red Giant and a Blue-White Dwarf.
What is the period of Algol?
2.87 daysAlgol, also called Beta Persei, prototype of a class of variable stars called eclipsing binaries, the second brightest star in the northern constellation Perseus. Its apparent visual magnitude changes over the range of 2.1 to 3.4 with a period of 2.87 days.
What is the Demon Star called?
AlgolFor someone who observes with the unaided eye, Algol (also known as the Demon Star) is quite possibly the most interesting star in the fall and winter skies, if they know when to look for its brightness changes.
How far is the Algol star from Earth?
92.95 light yearsAlgol / Distance to EarthAlgol is 92.8 light years from Earth; however, about 7.3 million years ago it passed within 9.8 light years and its apparent magnitude was approximately −2.5, considerably brighter than Sirius is today.
What color is the Algol star?
Algol is a main star in the constellation Perseus and makes up the constellation outline. Based on the spectral type (B8V) of the star, the Algol colour is blue .
Why is Algol so easy to find?
Algol is easy to find because it lies in a region of the sky that contains a number of bright stars that form identifiable patterns. Algol forms a triangle with Mirfak, the brightest star in Perseus, and Almach, the third brightest star in Andromeda.
Who discovered the variability of Algol?
In more recent times, Italian astronomer Geminiano Montanari has usually been credited for the discovery of Algol’s variability. Montanari noted that the star varied in brightness in 1667. The only non-nova variable star discovered before Algol was Mira, Omicron Ceti, identified by the Frisian astronomer Johannes Holwarda in 1638.
How old is Beta Persei Aa1?
The star spins considerably faster than the Sun, with a projected rotational velocity of 49 km/s. Its estimated age is 570 million years .
How often does the Alpha Persei star fade?
Most of the time, the Alpha Persei system has a visual magnitude of 2.1, but its brightness fades to magnitude 3.4 every 2.867328 days, when the larger but fainter orange subgiant star passes in front of the brighter primary component. This is the primary minimum of the system.
Which star is fainter, Algol or Epsilon Persei?
During the primary eclipses, it grows fainter than Epsilon Persei (mag. 2.88). Algol (β Persei) is a triple-star system (Algol A, B, and C) in the constellation Perseus, in which the large and bright primary Algol A is regularly eclipsed by the dimmer Algol B every 2.87 days.
Is Algol brighter than Almach?
At its usual brightness, Algol is slightly brighter than Almach (mag. 2.27). During the primary eclipses, it grows fainter than Epsilon Persei (mag. 2.88). Algol (β Persei) is a triple-star system (Algol ...
What time is the Algol system visible?
The Algol system is located within the constellation Perseus, which is visible from latitudes of between +90° and -35°, although best seen at about 9 PM (Local Time) during the month of December, when it is highest in the sky.
Where is the Algol system located?
The Algol system is located within the constellation Perseus, which is visible from latitudes of between +90° and -35°, although best seen at about 9 PM (Local Time) during the month of December, when it is highest in the sky. As can be seen from the image above, Capella in Auriga and the Pleiades in Taurus form a huge celestial triangle with Mirfak, the brightest star in Perseus, with Algol easily located just a few degrees to its right.
What are the X-rays from the Algol system?
The Algol system is also strong emitter of X-rays and radio wave flares , although the exact origins and/or causes of the emissions are not known for certain. In the case of the X-ray emissions, most investigators believe that these are caused by the magnetic fields of the primary stars interacting with the mass being transferred between them, while the radio flares are thought by some investigators to be caused by magnetic cycles on these stars that are somewhat similar to sunspots on the Sun. However, since the primary stars in the system have magnetic fields that are at least ten times more powerful than the Sun’s magnetic field, the observed radio flares from the Algol system is several times more powerful and persistent than similar emissions from the Sun.
How far away is Algol from Earth?
Algol, also cataloged as Beta Persei, lies some 93 light years from Earth. Like many stars, it’s a binary: a hot blue-white main sequence star about three times the diameter of our Sun, and a cooler yellow-orange star that’s started to grow long in the tooth.
Where is Algol visible?
Image credit: Georgia State University. You can see Algol in action for yourself. It’s easily visible in Perseus just east of Mirfak, the brightest star in the constellation.
What is the measure of the brightness of a variable star like Algol?
The measure of the brightness (or magnitude) of a variable star like Algol gives what’s called a light curve. An eclipsing variable gives the distinctive light curve shown below. The deep dip in brightness is the time when the faint star blocks the bright star. When the bright star blocks the faint star, you see a shallower dip in brightness.
Why are binary stars like Algol important?
They also enable direct determination of stellar brightness and mass that help astronomers refine theories and mathematical models of how stars work. It’s another example of how nature is sometimes generous: we can measure the true size and brightness of a star many trillions of miles away simply by careful observation and deduction, and infer the properties of thousands of other stars with these measurements. Science is a beautiful thing.
What does Algol mean in Greek mythology?
Its name comes from the Arabic al Ghul, “The Demon”, and in the Greek myths, Algol represents the head of Medusa, ...
How often does Algol eclipse?
As mentioned, the eclipses of Algol arrive every 2.867 days. To find out exactly when they occur in your time zone, this page has a useful predictor tool for Algol and several other bright variable stars. The measure of the brightness (or magnitude) of a variable star like Algol gives what’s called a light curve.
What does Algol represent?
Its name comes from the Arabic al Ghul, “The Demon”, and in the Greek myths, Algol represents the head of Medusa, the snake-haired gorgon, the head of which Perseus used to turn the sea monster Cetus to stone. The ancients also considered Algol to represent misfortune.
How long before the predicted minimum light is Algol?
Algol is at minimum light for about 20 minutes — as the large, dim star passes across the smaller, brighter one — then it gradually returns to normal.
Where is the Algol star?
Algol, the Demon Star, is located about 90 light-years away in the constellation Perseus, where it can be found as one of the eyes in Medusa's head as seen in Johannes Hevelius' Perseus illustration from Uranographia. (Image credit: Johanes Hevelius (Public Domain Image))
What does Algol mean?
The literal translation of Algol means, "The Mischievous One." Yet if the dimming of Algol was noticed by the ancient watchers of the night sky, the records say nothing about it.
Why is Algol called Algol?
The name Algol comes from the Arabic al-ghul, the female demon, but contrary to many popular accounts, the name apparently has nothing to do with the star's behavior. It is due merely to Algol's position marking the severed head of the Gorgon Medusa in ancient Greek constellation mythology.
How many days does Medusa wink?
So the eye of Medusa seems to "wink" at nearly three day intervals.
Who was the first person to see Algol winking?
The first person who definitely noticed Algol's winking behavior was the Italian professor of mathematics Geminiano Monta nari of Bologna around the year 1667. At that time the only other variable star known (save for a few novae) was Mira, whose light varies over months instead of hours. Perhaps this is why few other astronomers paid much attention to Montanari's discovery at the time. [ Top 10 Star Mysteries]
Who discovered the variability of Algol?
Algol's variability was rediscovered in 1782 by the English amateur astronomer John Goodricke, an 18-year-old deaf mute. He observed the star systematically and determined its period. Amazingly, he also correctly suggested the reason for the brightness variations: A large, dim body orbits the star and periodically blocks much of its light from our view.
How far away is Algol?
Algol is located approximately 93 light-years away. The bright component, Algol A, is about 90 times as bright as the sun. The eclipsing body, known as Algol B, is a subgiant star that is "dim" only in comparison to the bright star; it gives off about three times the sun's light.
How long does it take for Algol to go back to normal?
Best of all, Algol takes less than ten hours to go from its normal brightness down to its minimum light and then back to normal, so the star's whole performance can be watched in a single night when the schedule fits right. [ Top 10 Star Mysteries]
Why is Algol called Algol?
Its name comes from the Arabic word al-ghul, which means "female demon." But, contrary to popular belief, the name seems to have nothing to do with the star's behavior, but rather, is due merely to Algol's position marking the head of the Gorgon Medusa in ancient Greek mythology. According to the myth, gazing at Medusa could turn a person to stone.
How long does it take for an Algol to eclipse?
The whole eclipse requires nine hours and 40 minutes, and it occurs every 2 days, 20 hours, 48 minutes and 56.5 seconds.
Who discovered the variability of Algol?
Algol's variability was rediscovered in 1782 by the English amateur astronomer John Goodricke, an 18-year old deaf mute. Goodricke watched the star systematically and ultimately determined its period. It was also Goodricke who suggested the correct reason for the variations . Unlike Mira, whose brightness varies because it shrinks and swells, a large dim body orbits Algol, periodically blocking much of its light from our view.
Is Algol a regular eclipse?
Earlier I said that Algo l is "almost" as regular as clockwork. Over the years, amateur and professional astronomers who have made accurate timings of Algol’s eclipses have revealed that its period undergoes slight changes, amounting to only a few seconds.
Is Algol brighter than Epsilon Persei?
Most of the time, Algol is a bright as Gamma Andromedae, whose magnitude is +2.1. This magnitude is bright enough to be seen even through severe light pollution. At its dimmest, at magnitude +3.4, it is distinctly fainter than the nearby star Epsilon Persei. These two stars form a line with Algol that extends out from the constellation of Andromeda and can serve as comparisons.
How many miles is one light year?
A light-year is the distance light travels in one Earth year. One light-year is about 6 trillion miles (9 trillion km). That is a 6 with 12 zeros behind it!
How fast does light travel in space?
How can this be? Light travels at a speed of 186,000 miles (or 300,000 km) per second. This seems really fast, but objects in space are so far away that it takes a lot of time for their light to reach us.
How long does it take for the Sun to reach us?
Our Sun is the closest star to us. It is about 93 million miles away. So, the Sun's light takes about 8.3 minutes to reach us. This means that we always see the Sun as it was about 8.3 minutes ago. The next closest star to us is about 4.3 light-years away.
How far is 40 light-years?
In February 2017, astronomers detected seven Earth-sized planets orbiting a single star 40 light-years away from Earth. It's exciting news, but it begs the question: just how far away is that?
How many miles does light travel in a year?
As we established above, light travels 9,460,528,000,000 km in a year. So, we multiply that figure by 40 to give a total of 378,421,120,000,000 km. For those who use miles, that's 235,139,982,502,190 miles.
How many hours are there in a year?
If we divide our distance in km by 62,140 we get 6,089,815,256 hours. Let's use the Julian Year (used for astronomical calculations) of 8766 hours in a year, to take into account for the leap day every 4 years.
Is a light year a measure of time?
Unlike what the phrase may suggest at first glance, light-year isn't a measure of time - it's a measure of distance. The proper definition of a light-year would be " the distance light travels in a year ".
Star System
Algol Paradox
- Observations of Algol have challenged the basic theories of stellar evolution. A fundamental belief is that the more massive the star, the faster it evolves, leaves the main sequence and expands into a subgiant or giant. In a binary star system, components form at about the same time. In the case of Beta Persei, the less massive star – the secondary component – has already evolved int…
Algol Variables
- Algol is a prototype for a class of eclipsing variable stars known as Algol variables. These are semidetached binary star systems consisting of a main sequence star and a cooler, more evolved secondary component that fills its Roche lobe. Gas from the donor star is transferred to the companion and the mass transfer affects the evolution of the system. The inflowing gas often for…
Facts
- Algol may have been the first variable star discovered. Studies published in 2008 and 2013 found evidence that the periodicity of the star was documented in Ancient Egyptian Calendars of Lucky and Unlucky Days, written 3,000 years ago, and that the period of Algol was 2.85 days. The periodicity was noted in the Cairo Calendar, the best preserved of...
Name
- The name Algol (pronunciation: /ˈælɡɒl/) comes from the Arabic phrase raʾs al-ghūl, meaning “the head of the ogre.” Al Ghuloriginally meant “mischief-maker.” The name was officially approved by the International Astronomical Union’s (IAU) Working Group on Star Names (WGSN) on June 30, 2016. It formally applies only to the component Beta Persei Aa1. Algol has also been commonly …
Location
- Algol is easy to find because it lies in a region of the sky that contains a number of bright stars that form identifiable patterns. Algol forms a triangle with Mirfak, the brightest star in Perseus, and Almach, the third brightest star in Andromeda. These two stars can be found using the two prominent northern asterisms: the Great Square of Pegasus and Cassiopeia’s W. Andromeda’s …
Constellation
- Algol is located in the constellation Perseus. Perseus is the 24th largest constellation in the sky, stretching across an area of 615 square degrees of the northern sky between Auriga, Taurus, Aries, Triangulum, Andromeda, Cassiopeia and Camelopardalis. Representing the mythical Greek hero, it is one of the Greek constellations, first listed by the Greek astronomer Ptolemy in the 2n…