1.
Constellation
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A constellation is formally defined as a region of the celestial sphere, with boundaries laid down by the International Astronomical Union. The constellation areas mostly had their origins in Western-traditional patterns of stars from which the constellations take their names, in 1922, the International Astronomical Union officially recognized the 88 modern constellations, which cover the entire sky. They began as the 48 classical Greek constellations laid down by Ptolemy in the Almagest, Constellations in the far southern sky are late 16th- and mid 18th-century constructions. 12 of the 88 constellations compose the zodiac signs, though the positions of the constellations only loosely match the dates assigned to them in astrology. The term constellation can refer to the stars within the boundaries of that constellation. Notable groupings of stars that do not form a constellation are called asterisms, when astronomers say something is “in” a given constellation they mean it is within those official boundaries. Any given point in a coordinate system can unambiguously be assigned to a single constellation. Many astronomical naming systems give the constellation in which an object is found along with a designation in order to convey a rough idea in which part of the sky it is located. For example, the Flamsteed designation for bright stars consists of a number, the word constellation seems to come from the Late Latin term cōnstellātiō, which can be translated as set of stars, and came into use in English during the 14th century. It also denotes 88 named groups of stars in the shape of stellar-patterns, the Ancient Greek word for constellation was ἄστρον. Colloquial usage does not draw a distinction between constellation in the sense of an asterism and constellation in the sense of an area surrounding an asterism. The modern system of constellations used in astronomy employs the latter concept, the term circumpolar constellation is used for any constellation that, from a particular latitude on Earth, never sets below the horizon. From the North Pole or South Pole, all constellations south or north of the equator are circumpolar constellations. In the equatorial or temperate latitudes, the term equatorial constellation has sometimes been used for constellations that lie to the opposite the circumpolar constellations. They generally include all constellations that intersect the celestial equator or part of the zodiac, usually the only thing the stars in a constellation have in common is that they appear near each other in the sky when viewed from the Earth. In galactic space, the stars of a constellation usually lie at a variety of distances, since stars also travel on their own orbits through the Milky Way, the star patterns of the constellations change slowly over time. After tens to hundreds of thousands of years, their familiar outlines will become unrecognisable, the terms chosen for the constellation themselves, together with the appearance of a constellation, may reveal where and when its constellation makers lived. The earliest direct evidence for the constellations comes from inscribed stones and it seems that the bulk of the Mesopotamian constellations were created within a relatively short interval from around 1300 to 1000 BC
2.
Lyra
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It is one of 48 listed by the 2nd century astronomer Ptolemy, and is one of the 88 constellations recognized by the International Astronomical Union. Lyra was often represented on maps as a vulture or an eagle carrying a lyre. Beginning at the north, Lyra is bordered by Draco, Hercules, Vulpecula, Lyra is visible from the northern hemisphere from spring through autumn, and nearly overhead, in temperate latitudes, during the summer months. From the southern hemisphere, it is low in the northern sky during the winter months. Vega, Lyras brightest star is one of the brightest stars in the night sky, Beta Lyrae is the prototype of a class of stars known as Beta Lyrae variables. These binary stars are so close to other that they become egg-shaped. Epsilon Lyrae, known informally as the Double Double, is a multiple star system. Lyra also hosts the Ring Nebula, the second-discovered and best-known planetary nebula, in Greek mythology, Lyra represents the lyre of Orpheus. Made by Hermes from a shell, given to Apollo as a bargain. Orpheuss music was said to be so great that even objects such as trees, streams. Joining Jason and the Argonauts, his music was able to quell the voices of the dangerous Sirens, at one point, Orpheus married Eurydice, a nymph. While fleeing from an attack by Aristaeus, she stepped on a snake that bit her, to reclaim her, Orpheus entered the Underworld, where the music from his lyre charmed Hades. Hades relented and let Orpheus bring Eurydice back, on the condition that he never look back until outside. Unfortunately, near the end, Orpheus faltered and looked back. Orpheus spent the rest of his life strumming his lyre while wandering aimlessly through the land, there are two competing myths relating to the death of Orpheus. According to Eratosthenes, Orpheus failed to make a sacrifice to Dionysus due to his regard for Apollo as the supreme deity instead. Dionysus then sent his followers to rip Orpheus apart, ovid tells a rather different story, saying that women, in retribution for Orpheuss rejection of marriage offers, ganged up and threw stones and spears. At first, his music charmed them as well, but eventually their numbers and clamor overwhelmed his music, both myths then state that his lyre was placed in the sky by the muses
3.
United States Naval Observatory
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The USNO operates the Master Clock, which provides precise time to the GPS satellite constellation run by the United States Air Force. The USNO performs radio VLBI-based positions of quasars with numerous global collaborators, aside from its scientific mission, a house located within the Naval Observatory complex serves as the official residence of the Vice President of the United States. President John Quincy Adams, who in 1825 signed the bill for the creation of an observatory just before leaving presidential office, had intended for it to be called the National Observatory. The names National Observatory and Naval Observatory were both used for 10 years, until a ruling was passed to use the latter. Adams had made protracted efforts to bring astronomy to a level at that time. He spent many nights at the observatory, watching and charting the stars, established by the order of the United States Secretary of the Navy John Branch on 6 December 1830 as the Depot of Charts and Instruments, the Observatory rose from humble beginnings. Placed under the command of Lieutenant Louis M. Goldsborough, with an budget of $330, its primary function was the restoration, repair. It was made into an observatory in 1842 via a federal law. Lieutenant James Melville Gilliss was put in charge of obtaining the instruments needed, lt. Gilliss visited the principal observatories of Europe with the mission to purchase telescopes and scientific devices and books. The observatorys primary mission was to care for the United States Navys marine chronometers, charts and it calibrated ships chronometers by timing the transit of stars across the meridian. These facilities were listed on the National Register of Historic Places in 2017, the first superintendent was Navy Commander Matthew Fontaine Maury. Maury had the worlds first vulcanized time ball, created to his specifications by Charles Goodyear for the U. S. Observatory and it was the first time ball in the United States, being placed into service in 1845, and the 12th in the world. Maury kept accurate time by the stars and planets, the time ball was dropped every day except Sunday precisely at the astronomically defined moment of Mean Solar Noon, enabling all ships and civilians to know the exact time. Time was also sold to the railroads and was used in conjunction with railroad chronometers to schedule American rail transport, early in the 20th century, the Arlington Time Signal broadcast this service to wireless receivers. In 1849 the Nautical Almanac Office was established in Cambridge, Massachusetts as a separate organization and it was moved to Washington, D. C. in 1866, colocating with the U. S. Naval Observatory in 1893. On September 20,1894, the NAO became a branch of USNO, the astronomical measurements taken of the transit of Venus by a number of countries since 1639 resulted in a progressively more accurate definition of the AU. Relying heavily on methods, the naval observers returned 350 photographic plates in 1874. This calculated distance was a significant improvement over several previous estimates, the telescope used for the discovery of the Moons of Mars was the 26-inch refractor, then located at Foggy Bottom
4.
Brown dwarf
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Below this range are the sub-brown dwarfs, and above it are the lightest red dwarfs. Brown dwarfs may be fully convective, with no layers or chemical differentiation by depth, unlike the stars in the main-sequence, brown dwarfs are not massive enough to sustain nuclear fusion of ordinary hydrogen to helium in their cores. They are, however, thought to fuse deuterium and to fuse lithium if their mass is above a threshold of 13 MJ and 65 MJ. It is also debated whether brown dwarfs would be defined by their formation processes rather than by their supposed nuclear fusion reactions. Stars are categorized by spectral class, with brown dwarfs designated as types M, L, T, despite their name, brown dwarfs are of different colors. Many brown dwarfs would likely appear magenta to the human eye, Brown dwarfs are not very luminous at visible wavelengths. Planets are known to orbit some brown dwarfs, 2M1207b, MOA-2007-BLG-192Lb, at a distance of about 6.5 light years, the nearest known brown dwarf is Luhman 16, a binary system of brown dwarfs discovered in 2013. DENIS-P J082303. 1-491201 b is listed as the known exoplanet in NASAs exoplanet archive. However, a) the term black dwarf was already in use to refer to a white dwarf, b) red dwarfs fuse hydrogen. Because of this, alternate names for these objects were proposed, in 1975, Jill Tarter suggested the term brown dwarf, using brown as an approximate color. The term black dwarf still refers to a dwarf that has cooled to the point that it no longer emits significant light. The first self-consistent calculation of the minimum mass confirmed a value between 0.08 and 0.07 solar masses for population I objects. The discovery of deuterium burning down to 0.012 solar masses, however, such objects were hard to find as they emit almost no visible light. Their strongest emissions are in the spectrum, and ground-based IR detectors were too imprecise at that time to readily identify any brown dwarfs. Since then, numerous searches by various methods have sought these objects, for many years, efforts to discover brown dwarfs were fruitless. In 1988, however, a faint companion to a known as GD165 was found in an infrared search of white dwarfs. The spectrum of the companion GD 165B was very red and enigmatic and it became clear that GD 165B would need to be classified as a much cooler object than the latest M dwarfs then known. GD 165B remained unique for almost a decade until the advent of the Two Micron All Sky Survey which discovered many objects with similar colors, today, GD 165B is recognized as the prototype of a class of objects now called L dwarfs
5.
Aurora
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An aurora, sometimes referred to as a polar lights or northern lights, is a natural light display in the sky, predominantly seen in the high latitude regions. The resulting ionization and excitation of atmospheric constituents emits light of varying colour, the form of the aurora, occurring within bands around both polar regions, is also dependent on the amount of acceleration imparted to the precipitating particles. Precipitating protons generally produce optical emissions as incident hydrogen atoms after gaining electrons from the atmosphere, proton auroras are usually observed at lower latitudes. A region that currently displays an aurora is called the auroral oval, early evidence for a geomagnetic connection comes from the statistics of auroral observations. Elias Loomis, and later Hermann Fritz and S. Tromholt in more detail, day-to-day positions of the auroral ovals are posted on the internet. In northern latitudes, the effect is known as the Aurora Borealis or the Northern Lights, the former term was coined by Galileo in 1619, from the Roman goddess of the dawn and the Greek name for the north wind. The Aurora Australis is visible from southern latitudes in Antarctica, Chile, Argentina, New Zealand. A geomagnetic storm causes the auroral ovals to expand, and bring the aurora to lower latitudes and it was hardly ever seen near the geographic pole, which is about 2000 km away from the magnetic pole. The aurora can be seen best at this time, which is called magnetic midnight, Auroras also occur poleward of the auroral zone as either diffuse patches or arcs, which can be sub-visual. Auroras are occasionally seen in latitudes below the zone, when a geomagnetic storm temporarily enlarges the auroral oval. Large geomagnetic storms are most common during the peak of the sunspot cycle or during the three years after the peak. An aurora may appear overhead as a corona of rays, radiating from a distant and apparent central location, an electron spirals about a field line at an angle that is determined by its velocity vectors, parallel and perpendicular, respectively, to the local geomagnetic field vector B. This angle is known as the “pitch angle” of the particle, the distance, or radius, of the electron from the field line at any time is known as its Larmor radius. The pitch angle increases as the travels to a region of greater field strength nearer to the atmosphere. Thus it is possible for particles to return, or mirror. Other particles that do not mirror enter the atmosphere and contribute to the display over a range of altitudes. Other types of auroras have been observed from space, e. g. poleward arcs stretching sunward across the cap, the related theta aurora. These are relatively infrequent and poorly understood, there are other interesting effects such as flickering aurora, black aurora and sub-visual red arcs
6.
Karl G. Jansky Very Large Array
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The Karl G. Jansky Very Large Array is a radio astronomy observatory located on the Plains of San Agustin, between the towns of Magdalena and Datil, some 50 miles west of Socorro, New Mexico. It comprises 27 25-meter radio telescopes in a Y-shaped array and all the equipment, instrumentation, the VLA stands at an elevation of 6970 ft above sea level. It is a component of the National Radio Astronomy Observatory, the radio telescope comprises 27 independent antennae, each of which has a dish diameter of 25 meters and weighs 209 metric tons. The antennae are distributed along the three arms of a track, shaped in a wye -configuration, using the rail tracks that follow each of these arms—and that, at one point, intersect with U. S. The angular resolution that can be reached is between 0.2 and 0.004 arcseconds, there are four commonly used configurations, designated A through D. The observatory normally cycles through all the possible configurations every 16 months. Moves to smaller configurations are done in two stages, first shortening the east and west arms and later shortening the north arm and this allows for a short period of improved imaging of extremely northerly or southerly sources. The frequency coverage is 74 MHz to 50 GHz, the Array Operations Center for the VLA is located on the campus of the New Mexico Institute of Mining and Technology in Socorro, New Mexico. In 2011, a long upgrade project had resulted in the VLA expanding its technical capacities by factors of as much as 8,000. The 1970s era electronics were replaced with state-of-the-art equipment, on March 31,2012, the VLA was officially renamed in a ceremony inside the Antenna Assembly Building. In 1989 the VLA was used to receive communications from the Voyager 2 spacecraft as it flew by Neptune. It is not, despite depictions in culture such as the movie Contact. It has been used to carry out several surveys of radio sources, including the NRAO VLA Sky Survey. The driving force for the development of the VLA was David S. Heeschen and he is noted as having sustained and guided the development of the best radio astronomy observatory in the world for sixteen years. Congressional approval for the VLA project was given in August 1972, the first antenna was put into place in September 1975 and the complex was formally inaugurated in 1980, after a total investment of USD $78.5 million. It was the largest configuration of radio telescopes in the world, with a view to upgrading the venerable 1970s technology with which the VLA was built, the VLA has evolved into the Expanded Very Large Array. The upgrade has enhanced the sensitivity, frequency range. A second phase of this upgrade may add up to eight additional dishes in other parts of the state of New Mexico, up to 300 km away, in 1995 and 1996, the VLA was used for following up the Wow. signal from the SETI project
7.
New Mexico
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New Mexico is a state located in the southwestern region of the United States of America. It was admitted to the Union as the 47th state on January 6,1912 and it is usually considered one of the Mountain States. New Mexico is fifth by area, the 36th-most populous, inhabited by Native Americans for thousands of years before European exploration, New Mexico was colonized by the Spanish in 1598 Imperial Spanish viceroyalty of New Spain. Later, it was part of independent Mexico before becoming a U. S. territory and eventually a U. S. state as a result of the Mexican–American War. Among U. S. states, New Mexico has the highest percentage of Hispanics, the major Native American nations in the state are Navajo, Pueblo, and Apache peoples. The demography and culture of the state are shaped by these strong Hispanic and Native American influences and its scarlet and gold colors are taken from the royal standards of Spain, along with the ancient sun symbol of the Zia, a Pueblo-related tribe. New Mexico, or Nuevo México in Spanish, is incorrectly believed to have taken its name from the nation of Mexico. The name simply stuck, even though the area had no connection to Mexico or the Mexica Indian tribes, Mexico, formerly a part of New Spain, adopted its name centuries later in 1821, after winning independence from Spanish rule. New Mexico was a part of the independent Mexican Empire and Federal Republic of Mexico for 27 years,1821 through 1848, New Mexico and Mexico developed as neighboring Spanish-speaking communities under Spanish rule, with relatively independent histories. The states total area is 121,412 square miles, the eastern border of New Mexico lies along 103° W longitude with the state of Oklahoma, and 2.2 miles west of 103° W longitude with Texas. On the southern border, Texas makes up the eastern two-thirds, while the Mexican states of Chihuahua and Sonora make up the western third, the western border with Arizona runs along the 109°03 W longitude. The southwestern corner of the state is known as the Bootheel, the 37° N latitude parallel forms the northern boundary with Colorado. The states New Mexico, Colorado, Arizona, and Utah come together at the Four Corners in the corner of New Mexico. New Mexico, although a state, has very little water. Its surface water area is about 250 square miles, the New Mexican landscape ranges from wide, rose-colored deserts to broken mesas to high, snow-capped peaks. Despite New Mexicos arid image, heavily forested mountain wildernesses cover a significant portion of the state, the Sangre de Cristo Mountains, the southernmost part of the Rocky Mountains, run roughly north-south along the east side of the Rio Grande in the rugged, pastoral north. The most important of New Mexicos rivers are the Rio Grande, Pecos, Canadian, San Juan, the Rio Grande is tied for the fourth-longest river in the United States. Tourists visiting these sites bring significant money to the state, other areas of geographical and scenic interest include Kasha-Katuwe Tent Rocks National Monument and the Gila Wilderness in the southwest of the state
8.
Jupiter
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Jupiter is the fifth planet from the Sun and the largest in the Solar System. It is a giant planet with a mass one-thousandth that of the Sun, Jupiter and Saturn are gas giants, the other two giant planets, Uranus and Neptune are ice giants. Jupiter has been known to astronomers since antiquity, the Romans named it after their god Jupiter. Jupiter is primarily composed of hydrogen with a quarter of its mass being helium and it may also have a rocky core of heavier elements, but like the other giant planets, Jupiter lacks a well-defined solid surface. Because of its rotation, the planets shape is that of an oblate spheroid. The outer atmosphere is visibly segregated into several bands at different latitudes, resulting in turbulence, a prominent result is the Great Red Spot, a giant storm that is known to have existed since at least the 17th century when it was first seen by telescope. Surrounding Jupiter is a faint planetary ring system and a powerful magnetosphere, Jupiter has at least 67 moons, including the four large Galilean moons discovered by Galileo Galilei in 1610. Ganymede, the largest of these, has a greater than that of the planet Mercury. Jupiter has been explored on several occasions by robotic spacecraft, most notably during the early Pioneer and Voyager flyby missions and later by the Galileo orbiter. In late February 2007, Jupiter was visited by the New Horizons probe, the latest probe to visit the planet is Juno, which entered into orbit around Jupiter on July 4,2016. Future targets for exploration in the Jupiter system include the probable ice-covered liquid ocean of its moon Europa, Earth and its neighbor planets may have formed from fragments of planets after collisions with Jupiter destroyed those super-Earths near the Sun. Astronomers have discovered nearly 500 planetary systems with multiple planets, Jupiter moving out of the inner Solar System would have allowed the formation of inner planets, including Earth. Jupiter is composed primarily of gaseous and liquid matter and it is the largest of the four giant planets in the Solar System and hence its largest planet. It has a diameter of 142,984 km at its equator, the average density of Jupiter,1.326 g/cm3, is the second highest of the giant planets, but lower than those of the four terrestrial planets. Jupiters upper atmosphere is about 88–92% hydrogen and 8–12% helium by percent volume of gas molecules, a helium atom has about four times as much mass as a hydrogen atom, so the composition changes when described as the proportion of mass contributed by different atoms. Thus, Jupiters atmosphere is approximately 75% hydrogen and 24% helium by mass, the atmosphere contains trace amounts of methane, water vapor, ammonia, and silicon-based compounds. There are also traces of carbon, ethane, hydrogen sulfide, neon, oxygen, phosphine, the outermost layer of the atmosphere contains crystals of frozen ammonia. The interior contains denser materials - by mass it is roughly 71% hydrogen, 24% helium, through infrared and ultraviolet measurements, trace amounts of benzene and other hydrocarbons have also been found
9.
Io (moon)
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Io /ˈaɪ. oʊ/ is the innermost of the four Galilean moons of the planet Jupiter. It is the fourth-largest moon, has the highest density of all the moons and it was discovered in 1610 and was named after the mythological character Io, a priestess of Hera who became one of Zeuss lovers. With over 400 active volcanoes, Io is the most geologically active object in the Solar System, several volcanoes produce plumes of sulfur and sulfur dioxide that climb as high as 500 km above the surface. Ios surface is dotted with more than 100 mountains that have been uplifted by extensive compression at the base of Ios silicate crust. Some of these peaks are taller than Mount Everest, unlike most satellites in the outer Solar System, which are mostly composed of water ice, Io is primarily composed of silicate rock surrounding a molten iron or iron-sulfide core. Most of Ios surface is composed of extensive plains coated with sulfur, Ios volcanism is responsible for many of its unique features. Numerous extensive lava flows, several more than 500 km in length, the materials produced by this volcanism make up Ios thin, patchy atmosphere and Jupiters extensive magnetosphere. Ios volcanic ejecta also produce a large torus around Jupiter. Io played a significant role in the development of astronomy in the 17th and 18th centuries and it was discovered in January 1610 by Galileo Galilei, along with the other Galilean satellites. This discovery furthered the adoption of the Copernican model of the Solar System, the development of Keplers laws of motion, and the first measurement of the speed of light. In 1979, the two Voyager spacecraft revealed Io to be a geologically active world, with numerous volcanic features, large mountains, the Galileo spacecraft performed several close flybys in the 1990s and early 2000s, obtaining data about Ios interior structure and surface composition. These spacecraft also revealed the relationship between Io and Jupiters magnetosphere and the existence of a belt of high-energy radiation centered on Ios orbit, Io receives about 3,600 rem of ionizing radiation per day. Further observations have made by Cassini–Huygens in 2000 and New Horizons in 2007, as well as from Earth-based telescopes. From the surface of Io, Jupiter would subtend an arc of 19. 5°, although Simon Marius is not credited with the sole discovery of the Galilean satellites, his names for the moons were adopted. Based on a suggestion from Johannes Kepler in October 1613, he devised a naming scheme whereby each moon was named for a lover of the Greek mythological Zeus or his Roman equivalent. He named the innermost large moon of Jupiter after the Greek mythological figure Io, since the surface was first seen up close by Voyager 1, the International Astronomical Union has approved 225 names for Ios volcanoes, mountains, plateaus, and large albedo features. The approved feature categories used for Io for different types of volcanic features include patera, fluctus, vallis, named mountains, plateaus, layered terrain, and shield volcanoes include the terms mons, mensa, planum, and tholus, respectively. Named, bright albedo regions use the term regio, examples of named features are Prometheus, Pan Mensa, Tvashtar Paterae, and Tsũi Goab Fluctus
10.
Stellar classification
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In astronomy, stellar classification is the classification of stars based on their spectral characteristics. Electromagnetic radiation from the star is analyzed by splitting it with a prism or diffraction grating into a spectrum exhibiting the rainbow of colors interspersed with absorption lines, each line indicates an ion of a certain chemical element, with the line strength indicating the abundance of that ion. The relative abundance of the different ions varies with the temperature of the photosphere, the spectral class of a star is a short code summarizing the ionization state, giving an objective measure of the photospheres temperature and density. Most stars are classified under the Morgan–Keenan system using the letters O, B, A, F, G, K, and M. Each letter class is subdivided using a numeric digit with 0 being hottest and 9 being coolest. The sequence has been expanded with classes for other stars and star-like objects that do not fit in the system, such as class D for white dwarfs. In the MK system, a luminosity class is added to the class using Roman numerals. This is based on the width of absorption lines in the stars spectrum. The full spectral class for the Sun is then G2V, indicating a main-sequence star with a temperature around 5,800 K, the conventional color description takes into account only the peak of the stellar spectrum. This means that the assignment of colors of the spectrum can be misleading. There are no green, indigo, or violet stars, likewise, the brown dwarfs do not literally appear brown. The modern classification system is known as the Morgan–Keenan classification, each star is assigned a spectral class from the older Harvard spectral classification and a luminosity class using Roman numerals as explained below, forming the stars spectral type. The spectral classes O through M, as well as more specialized classes discussed later, are subdivided by Arabic numerals. For example, A0 denotes the hottest stars in the A class, fractional numbers are allowed, for example, the star Mu Normae is classified as O9.7. The Sun is classified as G2, the conventional color descriptions are traditional in astronomy, and represent colors relative to the mean color of an A-class star, which is considered to be white. The apparent color descriptions are what the observer would see if trying to describe the stars under a dark sky without aid to the eye, or with binoculars. However, most stars in the sky, except the brightest ones, red supergiants are cooler and redder than dwarfs of the same spectral type, and stars with particular spectral features such as carbon stars may be far redder than any black body. O-, B-, and A-type stars are called early type
18h 35m 37.902s, +32° 59′ 54.59″
. Bibcode:2003AJ....125.1598L. doi:10.1086/345972.
