Azophi's Book of Fixed Stars, published in 964, describes more than a thousand stars in detail and provides the first descriptions of the Andromeda Galaxy and the Large Magellanic Cloud. Johann Bayer's Uranometria star atlas was published in 1603 with over 1200 stars. Names are made of Greek letters combined with constellation name, for example Alpha Centauri. John Flamsteed's Historia coelestis Britannica star atlas, published in 1725, lists stars using numbers combined with constellation and ordered by right ascension, for example 61 Cygni. Messier Catalog – The Messier objects are a set of astronomical objects first listed by French astronomer Charles Messier in 1771.
It is faintly visible to the naked eye, having a combined apparent visual magnitude of +5.60. Based upon an annual parallax shift of 15.39 mas as seen from Earth, it is located around 212 light years from the Sun. The system is deemed to be a member of the Sirius supercluster of stars that share a common motion through space. The primary, component A, is a white-hued A-type subgiant star with a stellar classification of A4 IV. It is a microvariable, showing a 0.0056 change in magnitude with a frequency of 0.16245 times per day. Epsilon Pyxidis has been catalogued as an Am star, although this remains uncertain.
18 Drag Dra
With an apparent visual magnitude of 4.84, it is just bright enough to be faintly visible to the naked eye. The distance to this system, as estimated from an annual parallax shift of 4.5 mas, is roughly 720 light years. It is moving closer to the Sun with a heliocentric radial velocity of −1.4 km/s, and is a probable member of the Sirius stream of co-moving stars. The visible component has a stellar classification of K0 III CN−0.5 CH−2 Ca1, indicating it is an evolved K-type giant star with some abundance peculiarities in its atmosphere. At the age of around 280 million years, it is most likely (99% chance) on the horizontal branch.
64 Aurigae is a single star located 312 light years away from the Sun in the northern constellation of Auriga. It is visible to the naked eye as a dim, white-hued star with an apparent magnitude of 5.87. The star is moving closer to the Earth with a heliocentric radial velocity of −10, and may come to within 51.11 pc in around 5.3 million years. It is a member of the Sirius supercluster. This object is an ordinary A-type main-sequence star with a stellar classification of 5 Vn, where the 'n' notation is used to indicate "nebulous" lines in the spectrum caused by rapid rotation. It is 291 million years old with a projected rotational velocity of 212 km/s.
Beta Canis Majoris (β Canis Majoris, abbreviated Beta CMa, β CMa), also named Mirzam, is a star in the southern constellation of Canis Major, the "Great Dog", located at a distance of about 500 light-years (150 parsecs) from the Sun. In the modern constellation it lies at the position of the dog's front leg. Beta Canis Majoris is the star's Bayer designation. The traditional names Mirzam, Al-Murzim or Murzim, derive from the Arabic for 'The Herald', and probably refers to its position, heralding (i.e., rising before) Sirius in the night sky. In 2016, the International Astronomical Union organized a Working Group on Star Names (WGSN) to catalog and standardize proper names for stars.
It is visible to the naked eye with an apparent visual magnitude of 3.93. The distance to this star is roughly 520 light years, based upon an annual parallax shift of 0.00625 arcseconds. If the star were 10 pc from the Sun, it would be the brightest star in the night sky with an apparent magnitude of −2.84. (Currently, the brightest star is Sirius at magnitude −1.46.) This is a B-type subgiant star with a stellar classification of B1.5 IV. It is a hybrid pulsator variable, lying as it does on the overlapping instability strips for Beta Cephei variables and slowly pulsating B-type stars.
6 Canis Minoris is a star in the equatorial constellation of Canis Minor, located around 570 light years away from the Sun. It is visible to the naked eye as a faint, orange-hued star with an apparent visual magnitude of +4.55. This object is moving closer to the Earth with a heliocentric radial velocity of −16.3 km/s. Kinematically, it is a member of an outlying group belonging to the Ursa Major flow of the Sirius supercluster. This is an evolved giant star with a stellar classification of K1 III. It has a mild barium anomaly, which may indicate this is a binary star system with a white dwarf companion.
List of discoveriesBuckland 1823Discoveries of paleoanthropology 21st century
Accelerating universe. exoplanets. 1912, September 17, the first radial velocity of a spiral type galaxy (designated: M31 ) – Vesto Slipher. 1907 – 1921, approximately 2'400 variable stars, – Henrietta Swan Leavitt. 1916, theoretical existence of gravitational waves – Albert Einstein. 1925, hypothesis that the universe is expanding based on observation of stars and galaxies being in motion away from the earth in every direction and the rate of motion being greater in relation to the greater distance of astronomical structure – Edwin Hubble. 1963, radiowave source 3C 273, later defined as a quasi-stellar radio source, a quasar, – Maarten Schmidt (using Mt.
CirCircinus (constellation)Circinus constellation
Circinus is a faint constellation, with only one star brighter than fourth magnitude. Alpha Circini, a white main sequence star with an apparent magnitude of 3.19, is 54 light-years away and 4° south of Alpha Centauri. Not only the brightest star in the constellation, it is also the brightest example of a rapidly oscillating Ap (RoAp) star in the night sky. It has the unusual spectral type A7 Vp SrCrE, showing increased emissions of strontium, chromium and europium. Stars of this type have oddly localised magnetic fields and are slightly variable.
TW Piscis AustriniFomalhaut AAlpha Piscis Austrini
However, its southerly declination is not as great as that of stars such as Acrux, Alpha Centauri and Canopus, meaning that, unlike them, Fomalhaut is visible from a large part of the Northern Hemisphere as well. Its declination is greater than that of Sirius and similar to that of Antares. At 40°N, Fomalhaut rises above the horizon for eight hours and reaches only 20° above the horizon, while Capella, which rises at approximately the same time, will stay above the horizon for twenty hours. Fomalhaut can be located in northern latitudes by the fact that the western (right-hand) side of the Square of Pegasus points to it.
The star is located approximately 2,630 light-years away in the constellation of Monoceros. The apparent magnitude of this star is 13.6, which means it is not visible to the naked eye; however, it can be seen through a medium-sized amateur telescope on a clear, dark night. The first exoplanet discovered in the course of the COROT mission orbits this star; it is considered to be a "hot Jupiter", and is approximately as massive as the planet Jupiter itself.
Xi Orionis (ξ Orionis) is a binary star system in the northeastern part of the constellation of Orion, well above the red giant star, Betelgeuse in the sky. It lies next to another blue main-sequence star, Nu Orionis which is somewhat closer at 520 light years. The apparent visual magnitude of Xi Orionis is 4.47, which is bright enough to be seen with the naked eye. The distance to this star, as determined using the parallax method, is roughly 610 light years. This is a spectroscopic binary star system with an orbital period of 45.1 days and an eccentricity of 0.26. The primary component is a B-type subgiant star with a stellar classification of B3 IV.
Lyramong the starsConstellation of Orpheus
The true nova HR Lyrae flared in 1919 to a maximum magnitude of 6.5, over 9.5 magnitudes higher than in quiescence. Some of its characteristics are similar to those of recurring novae. M57, also known as the "Ring Nebula" and NGC 6720, has a diameter of one light-year and is at a distance of 2,000 light-years from Earth. It is one of the best known planetary nebulae and the second to be discovered; its integrated magnitude is 8.8. It was discovered in 1779 by Antoine Darquier, 15 years after Charles Messier discovered the Dumbbell Nebula. Astronomers have determined that it is between 6,000 and 8,000 years old; it is approximately one light-year in diameter.
In List of stars nearer than five parsecs by Peter van de Kamp (1930) its parallax is 0.34 arcsec (distance is 2.94 pc or 9.59 ly), and it is the 7th closest star system after Alpha Centauri ABC, Barnard's Star, Wolf 359, Lalande 21185, Sirius AB and BD-12 4523. In Stars within ten parsecs of the Sun by Louise Freeland Jenkins (1937) its parallax is 0.34 arcsec (distance is 2.94 pc or 9.59 ly), and it is the 6th closest star system after Alpha Centauri, Barnard's Star, Wolf 359, Lalande 21185 and Sirius.
α Apodisα Aps
Alpha Apodis (Alpha Aps, α Apodis, α Aps) is the brightest star in the southern circumpolar constellation of Apus, with an apparent magnitude of approximately 3.825. It had the Greek alpha designation as part of the constellation which Johann Bayer called Apis Indica in his 1603 Uranometria star atlas. With a declination of –79°, this is a circumpolar star for much of the southern hemisphere. It can be identified on the night sky by drawing an imaginary line through Alpha Centauri and Alpha Circini then extending it toward the south celestial pole.
This table lists those stars or other objects which have Bayer designations by the constellation in which those stars or objects lie. The name given is that of the article if it does not reflect the Bayer designation (e.g. Aldebaran instead of Alpha Tauri). Abbreviations are used in other cases.
With an apparent visual magnitude of 5.17, it is faintly visible to the naked eye on a clear, dark night. Based upon an annual parallax shift of 0.00156 arcseconds, it is located around 209 light years from the Sun. The star is considered a member of the Sirius supercluster. This is an ordinary A-type main sequence star with a stellar classification of A2 V, indicating that it is generating energy through the thermonuclear fusion of hydrogen into helium in its core region. It is around 450 million years old and has a relatively high rate of rotation with a projected rotational velocity of 194 km/s.
32 Perl Per
32 Persei is a single star located 149 light years away from the Sun in the northern constellation of Perseus. It has the Bayer designation of l Persei, while 32 Persei is the Flamsteed designation. This object is visible to the naked eye as a faint, white-hued star with an apparent visual magnitude of 4.96. It is moving closer to the Earth with a heliocentric radial velocity of −9 km/s, and is a member of the Sirius supercluster: a stream of stars that share a common motion through space. This is an ordinary A-type main-sequence star with a stellar classification of A3V. It is around 125 million years old with a high rate of spin, showing a projected rotational velocity of 144 km/s.
List of traditional star namesby constellationformally named
Only a handful of the brightest stars have individual proper names not depending on their asterism; so Sirius "the scorcher", Antares "like Mars", Canopus (of uncertain origin), Alphard "the solitary one", Regulus "kinglet"; and arguably Aldebaran "the follower" (of the Pleiades), Procyon "preceding the dog [Sirius]". The same holds for Chinese star names, where most stars are enumerated within their asterisms, with a handful of exceptions such as 織女 "weaving girl" (Vega). In addition to the limited number of traditional star names, there are some coined in modern times, e.g. "Avior" for Epsilon Carinae (1930), and a number of stars named after people (mostly in the 20th century).
standard candlestandard candlesdistance
The brightness of an object can be expressed in terms of its absolute magnitude. This quantity is derived from the logarithm of its luminosity as seen from a distance of 10 parsecs. The apparent magnitude, the magnitude as seen by the observer (an instrument called a bolometer is used), can be measured and used with the absolute magnitude to calculate the distance D to the object in kiloparsecs (where 1 kpc equals 1000 parsecs) as follows: or where m is the apparent magnitude and M the absolute magnitude. For this to be accurate, both magnitudes must be in the same frequency band and there can be no relative motion in the radial direction.
This theory is supported by the fact that the Eddington limit for a source of this magnitude means that the mass of generating object cannot be less than. The source's observed strength has varied by up to 50% over a 10-year span, which is also consistent with an accretion disc X-ray source. An optical counterpart to NGC 5204 X-1 was discovered in 2001 using the X-ray data from Chandra and a series of observations in the visible spectrum from the Hubble Space Telescope. With an apparent magnitude of 19.7 despite a distance of more than 14 million light-years, which corresponds to an absolute magnitude of -8.7, it is most likely a large type B or type O supergiant star.
HD 121504 is an 8th magnitude star in the constellation of Centaurus. It is a yellow dwarf (spectral type G2V) and remarkably similar to our Sun, only slightly brighter like α Centauri A. However, it is located at a distance of about 135 light years and thus is not visible to the unaided eye; binoculars or small telescope is required to see this star. Another component, designated as SAO 241323 has been proposed as a component of the system. However, the star is an optical binary component and in reality is a white giant star located thousands of light years away.
υ Andromedaeυ AndUpsilon Andromedae A
Upsilon Andromedae A has an apparent magnitude of +4.09, making it visible to the naked eye even under moderately light-polluted skies, about 10 degrees east of the Andromeda Galaxy. The Catalog of Components of Double and Multiple Stars and Washington Double Star Catalog (WDS) both list two companion stars: magnitude 12.6 UCAC3 263-13722 110" away, listed as component B; and magnitude 10.3 F2 star TYC 2822-2067-1 280" away, listed as component C. A fainter and closer star discovered in 2002, is confusingly referred to in the discovery paper as υ Andromedae B even though that designation is also used for a different companion.
55 Andromedae, abbreviated 55 And, is a single, orange-hued star in the northern constellation of Andromeda. 55 Andromedae is the Flamsteed designation. It is visible to the naked eye with an apparent visual magnitude of 5.42. Based upon an annual parallax shift of 4.7 mas, it is located about 730 light years from the Sun. 55 And is moving closer to the Earth with a heliocentric radial velocity of −7.6 km/s. It is a member of the Sirius supercluster. This is an aging giant star with a stellar classification of K1 III, which indicates it has exhausted the hydrogen supply at its core and evolved away from the main sequence.
It is faintly visible to the naked eye with an apparent visual magnitude of 4.74. The distance to this star, based upon an annual parallax shift of 10.37 mas, is around 315 light years. With a stellar classification of M3 III, this is a red giant star on the asymptotic giant branch. It is a suspected small amplitude variable. The measured angular diameter of the star after correcting for limb darkening is 5.64 mas, which, at the estimated distance of this star, yields a physical size of about 58 times the radius of the Sun. It is radiating 464 times the solar luminosity from its outer atmosphere at an effective temperature of about 3,725 K.