Epsilon Eridani (ε Eri, ε Eridani) is a star in the southern constellation Eridanus, just south of the celestial equator. It can be seen from most of Earth's surface.
It is 10.5 light years (ly) away, and has an apparent magnitude of 3.73. It is the third closest individual star or star system visible to the unaided eye.
Epsilon Eridani was the closest star known to host a planet until the unconfirmed discovery of Alpha Centauri Bb. Its age is less than a billion years. Because of its youth, Epsilon Eridani has a more active magnetic field than the present-day Sun. Its stellar wind is 30 times as strong. Its rotation period is 11.2 days at the equator. The star is smaller and less massive than the Sun, and has a lower level of metal elements. It is a main-sequence star of spectral class K2, which means that energy generated at the core through nuclear fusion of hydrogen is emitted from the surface at a temperature of about 5,000 K, giving it an orange hue.
Its planet, Epsilon Eridani b, was announced in 2000. The planet orbits in about 7 years. It is about 3.4 astronomical units (AU) away from its star.
The system includes two belts of rocky asteroids: one at about 3 AU and a second at about 20 AU, whose structure may be maintained by a hypothetical second planet, Epsilon Eridani c. Epsilon Eridani has an extensive outer debris disk of remnant planetesimals left over from the system's formation.
Epsilon Eridani may be a member of the Ursa Major Moving Group of stars that share a similar motion through the Milky Way. This suggests they share a common origin in an open star cluster. Its nearest neighbor, the binary star system Luyten 726-8, will have a close encounter with Epsilon Eridani in about 31,500 years when they will be separated by about 0.93 ly.
Epsilon Eridani has been the target of SETI searches. Epsilon Eridani appears in science fiction stories and has been suggested as a destination for interstellar travel.
Star system
A star system or stellar system is a small number of stars which orbit each other, bound by gravitational attraction. A large number of stars bound by gravitation is generally called a "star cluster" but, broadly speaking, they are also star systems. Star systems are not to be confused with planetary systems, which include planets and similar bodies.
A stellar system of two stars is known as a "binary star", "binary star system" or "physical double star". If there are no tidal effects, no disturbance from other forces, and no transfer of mass from one star to the other, such a system is stable. Both stars will orbit around the center of mass of the system indefinitely. Examples of binary systems are Sirius, Procyon and Cygnus X-1, the last of which probably consists of a star and a black hole.
It is possible to have star systems with more than two members. Their stars are gravitationally bound to each other, and may or may not be close to each other.
A recently discovered quintuple star system (five stars) is known as 1SWASP J093010.78+533859.5. The system has two sets of binary stars, one of them with a small third star. The two sets are a long way apart, further than the orbit of Pluto is to the Sun. The binary stars are close to each other and one binary has touching stars, with their outer ionised gases mixing. That situation is called a contact binary. From the data collected, the authors are fairly sure that both binaries (and probably all five stars) are gravitationally bound in a single system. The angles of inclination (the angle between the two orbital planes) of the two binaries (88.2(3) and 86(4) degrees). This suggests they originally formed by break-up (~9-10 billion years ago ago) from a single protostellar disk. Afterwards, they stayed in the same orbital plane.
Most multiple star systems are "triple stars". Systems with four or more components are less likely to occur.
Multiple star systems are smaller than open star clusters, which have more complex dynamics and typically have from 100 to 1,000 stars. Most multiple star systems known are triple. For example, in the 1999 revision of
Tokovinin's catalog of physical multiple stars,
551 out of the 728 systems described are triple.
Multiple-star systems can be divided into two main types: systems which are stable, or systems with chaotic behavior. Chaotic ones are usually of young stars in systems not yet disrupted by chaos.
Kentaro Sato
Kentaro Sato (佐藤 賢太郎 Satō Kentarō, born 12 May 1981), aka Ken-P, is a composer and conductor of media music and concert music.
Sato was born in Hamamatsu, Shizuoka, Japan. He holds a Master of Music in Conducting and a Bachelor of Music in Media and Commercial Writing from California State University, Northridge (CSUN). In addition to his degree in music, he also holds a degree in cinema from Santa Monica College. He is famous for his works for chorus and orchestra, and video game music.
Open star cluster
An open star cluster, also known as galactic cluster, is a group of a few hundred or thousand stars. They have roughly the same age, and were formed from the same giant molecular cloud.
More than 1,100 open clusters have been discovered within the Milky Way Galaxy, and many more are thought to exist. They are loosely bound together by mutual gravitational attraction, but they get disrupted by close encounters with other clusters and clouds of gas. Open clusters generally survive for a few hundred million years, with the most massive ones surviving for a few billion years.
In contrast, the more massive globular clusters of stars exert a stronger gravitational attraction on their members. So, they can survive for longer. Open clusters have been found only in spiral and irregular galaxies, in which active star formation is occurring.
Young open clusters may still be in the molecular cloud from which they formed. They light it up and create an H II region. Over time, radiation pressure from the cluster will disperse the molecular cloud. Typically, about 10% of the mass of a gas cloud will form stars before radiation pressure drives the rest of the gas away.
Open clusters are key objects in the study of stellar evolution. The cluster members are of similar age and chemical composition, so their properties (such as distance, age and chemical composition) are more easily studied than for isolated stars. A number of open clusters, such as the Pleiades, Hyades or the Alpha Persei Cluster are visible with the naked eye.
Survivor Series (1988)
Survivor Series (1988) was a professional wrestling pay-per-view show made by World Wrestling Federation (WWF). It was held on November 24, 1988 at the Richfield Coliseum in Richfield Township, Ohio. It was the second Survivor Series event that was held by the WWF.
Survivor Series (1989)
Survivor Series (1989) was a professional wrestling pay-per-view show made by World Wrestling Federation (WWF). It was held on November 23, 1989 at the Rosemont Horizon in Rosemont, Illinois. It was the third Survivor Series event that was held by the WWF.
Stockholm Marathon
The Stockholm Marathon is an annual marathon event in Stockholm, Sweden. Held since
1979, it also serves as the Swedish national marathon championship.
Key:
Saltsjöbaden
Saltsjöbaden is a locality in Nacka Municipality, Stockholm County, Sweden. In 2010, 9,491 people lived there. It is located on the Baltic Sea coast.
Speak Now
Speak Now is the third studio album by American singer-songwriter Taylor Swift. It was released on October 25, 2010 by Big Machine Records. The album was written by Swift herself (other writers helped write her previous albums).
"Speak Now" is in a country-pop style similar to Swift's other work. A deluxe edition was sold in Target stores. That version has three new songs (including the single "Ours") and two acoustic versions of songs on the original. Throughout 2011, Swift promoted the album on the Speak Now World Tour.
Saltsjöbaden Agreement