Bootes Constellation on Top Astronomer Bootes Please hover over any star to get more information Bootes, or "the Herdsman," is a constellation in the northern hemisphere, first documented by the Greek astronomer Ptolemy in the 2nd century. Its name means "herdsman" or "plowman" in Greek. The Greeks used to call the constellation Arctophylax ("bear watcher" or "bear keeper"). Bootes is usually visualized as a herdsman holding a staff and two dogs on a leash, chasing Ursa Major around the pole. The origin of the name is not certain, but the constellation is associated with several myths. In one, Bootes represents a ploughman who drove the oxen which were tied to the polar axis, in the Ursa Major constellation , with his two dogs, which belong to the constellation Canes Venatici . Bootes' work, in other words, kept the skies turning. In other legends, Bootes is identified with Atlas because of the position of the constellation's arms near the pole star. Bootes is also said to have invented the plough, which earned him a place in the heavens.

Another myth identifies the constellation with the Ursa Major story and Arcas, the son of Zeus and Callisto, raised by his mother's father, Lycaon. When Zeus visited Lycaon, the latter served him his son for dinner to verify that it was really the god himself at his table. In retribution, the angry Zeus transformed Lycaon into a wolf. Meanwhile, Arcas' mother Callisto had been transformed into a bear by Zeus' jealous wife Hera. Not recognizing her in the forest, Arcas once began to chase her. Callisto hid herself in a temple, a place that was not to be desecrated, and faced the punishment of death. Zeus, however, decided that she should be placed in the sky instead, as well as her son: she became Ursa Major and he, Bootes. Yet another Greek legend identifies Bootes as Icarius, a grape grower whom the god Dionysus had taught to make wine. When they tasted the wine, Icarius' friends became so intoxicated that they believed they had been poisoned and killed him. When Icarius' dog Maera brought his daughter Erigone to his body, she hanged herself in despair and the dog died of grief.

Zeus transformed them to constellations: Icarius became Bootes, Erigone was turned into the Virgo constellattion , and the dog became either Canis Major or Canis Minor , depending on the source. The Bootes constellation occupies an area of 907 square degrees and contains four stars with known planets. It can be seen at latitudes between +90° and -50° and is best visible at 9 p.m. during the month of June. Bootes is home to [876] Arcturus or alpha Bootis, the third brightest star in the sky. Arcturus is a red giant 36.7 light-years distant and about 110 times more luminous than the Sun. Its proper motion is larger than that of any first magnitude star except [2081] alpha Centauri. Its name is derived from the Greek word Arktouros, meaning "guardian of the bear." In mythology, Zeus placed the star in the sky to protect Callisto and Arcas from Hera’s jealousy.

In other cultures, the star is also known as Aramec, Azimech, Alramih and Haris-el-sema ("the keeper of heaven"). It is the zenith star in Hawaii. Prehistoric Polynesian sailors called it Hokulea, or the "Star of Joy." Ancient Greeks believed the star to portend tempestuous weather. The Chinese call it Da Jiao ("great horn"), while Inuit astronomers call the star "the Old Man." [881] beta Bootis or Nekkar ("cattle driver"), is a yellow G-type giant about 219 light-years distant from Earth- It is also known by the name Meres. [879] gamma Bootis or Seginus, is a Delta Scuti type variable star with an apparent magnitude between 3.02 and 3.07. [878] epsilon Bootis, Izar ("veil") or Pulcherrima (“loveliest”), is a binary star composed of a bright orange giant and a main sequence star. Its other traditional names are Mirak ("the loins") and Mizar.

[877] eta Bootis, also known as Saak and Muphrid ("the single one of the lancer"), is Arcturus’ first neighbour, a spectroscopic binary that has a notable excess of elements heavier than hydrogen. [886] mu Bootis, is also known as Alkalurops ("shepherd’s staff"), Inkalunis, Clava and Venabulum. It is a triple star system with a yellow-white F-type subgiant for a primary component. [890] kappa Bootis or Asellus Tertius ("third donkey colt"), is a white-yellowish star system that has a binary system for a primary and a Delta Scuti type variable star for a companion. Constellations: Bootes - Windows to the Universe The Constellation Bootes, the Herdsman Click on image for full size Bootes Bootes, the herdsman, rides through the sky during the late Spring and early Summer. While he may have appeared as a shepherd to the ancients, modern star-gazers like us can easily recognize the shape of a kite, with the bright star Arcturus at the point of the kite where the tail is attached.

Arcturus is a bright red supergiant star with a diameter nearly 20 times that of the Sun and a brightness more than 100 times that of our Sun. Since it is only 36 light-years away (close for a star!), it appears as the brightest star in Bootes, and, in fact, the fourth brightest star in the sky. Bootes was identified with a farmer who plows the land during spring. The Romans called Bootes the Herdsman of the Septemtriones, that is, of the seven oxen represented by the seven stars of the Big Dipper , which was seen as the cart or the plow. Shop Windows to the Universe Science Store! The Fall 2009 issue of The Earth Scientist , which includes articles on student research into building design for earthquakes and a classroom lab on the composition of the Earthï¿½s ancient atmosphere, is available in our online store . Windows to the Universe Community News Arcturus cuts through galaxy's disk | Brightest Stars | EarthSky Arcturus is roughly 25 times greater in diameter than our sun. Arcturus / Antares/ sun size comparison from Wikimedia Commons .

Arcturus, brightest star in the constellation Bootes What does the proper motion of Arcturus tell us? It tells us that Arcturus is moving at a tremendous rate of speed (122 km/s) relative to our solar system. Moreover, Arcturus is not moving with the general stream of stars in the flat disk of our Milky Way galaxy. Instead, it is cutting perpendicularly through the galactic disk. Arcturus is thought to be an old star. It appears to be moving with a group of at least 52 other such stars, known as the Arcturus stream. Arcturus is likely to be considerably older than our sun. When the sun evolves to become a red giant, the sun might be a star much like Arcturus is now. As it cuts through the galactic disk, Arcturus will eventually reach a closest point to our sun. The closest approach of Arcturus will happen in about 4,000 years, when the star will be a few hundredths of a light-year closer to Earth than it is today. But remember that Arcturus is not moving with the general stream of stars in the disk of our Milky Way galaxy.

Thus, we will lose sight of this star relatively quickly. Millions of years from now, this star will be lost from the view of any future inhabitants of Earth, or at least those who are earthbound and looking with the eye alone. The red giant Arcturus is roughly 25 times the diameter of our sun. It is not the largest of the red giant, however, as the diagram below shows. Because of its larger size, in visible light Arcturus radiates more than 100 times the light of our sun. If you consider infrared and other forms of radiant energy, Arcturus is about 200 times more powerful than the sun. Its mass is hard to exactly determine, but may be slightly greater than that of our sun (1.1-0.4+0.6 solar mass). The reddish or orange color of Arcturus signifies its temperature, which is about 7,300 degrees Fahrenheit. That makes it several thousand degrees cooler than the surface of the sun. Arcturus is the brightest star in the kite-shaped constellation Bootes. Spring evenings are a good time to “follow the arc to Arcturus.” Face east. Find the Big Dipper.

Follow the curve in the Dipper’s handle to the orange star Arcturus. How to see the star Arcturus. Arcturus is the alpha star of a cone-shaped constellation called Bootes the Herdsman. It is far enough north on the sky’s dome that – for northern hemisphere observers – it’s visible during some part of the night throughout most of the year. You might notice this bright orange star passing high overhead on late spring evenings. In summer, Arcturus is high overhead shortly after dark. Autumn observers need to look early because then it sets by mid-evening. The best time to observe it in winter is in the wee hours before dawn. Our chart shows this constellation as you stand facing south on spring evenings. Seeing a Herdsman in these stars might be difficult, but the constellation is easy to imagine as a kite. There’s an easy mnemonic for remembering how to identify this bright, orange star. Just remember the phrase: follow the arc to Arcturus. First, locate the Big Dipper in the northern sky. Notice that the handle of the Big Dipper is a curve or arc. Extend this curve past the end of the Big Dipper’s handle, and you will come to Arcturus.

Arcturus is the brightest star north of the celestial equator. What does that mean? Imagine that Earth’s equator can be projected onto the sky. This line above Earth’s equator is called the celestial equator. It divides the sky into northern and southern hemispheres, just as Earth’s equator does for Earth. The three brightest stars of the sky – Sirius, Canopus and Alpha Centauri – are south of the celestial equator. Meanwhile, Arcturus is the brightest star in the northern part of the sky. It is only marginally brighter than the northern hemisphere’s second-brightest star, Vega . To the eye, Arcturus and Vega reign as co-stars in the northern half of the sky. Johannes Hevelius drew the constellation in Uranographia, his celestial catalogue in 1690. The view is mirrored following the tradition of celestial globes, showing the celestial sphere in a view from “ouside.” (Wikimedia Commons) History and mythology of Arcturus. Arcturus’ constellation Bootes – the Herdsman – is sometimes pictured as guarding the Great Bear, or Ursa Major, which contains the Big Dipper asterism.

We sometimes hear Arcturus called the Bear Guard. In China, the constellation for which Arcturus is the chief star was sometimes called the Dragon. In some classical Greek stories, Bootes was Icarus, who in another story flew too close to the sun. Passing directly over the Hawaiian Islands, Arcturus was a particularly important navigational star to the islands’ native inhabitants and other Polynesians. The translation may be questioned, but Arcturus is among the few stars mentioned in the Bible. (“Which maketh Arcturus, Orion, and Pleiades, and the chambers of the south” – Job 9:9 and “Canst thou bring forth Mazzaroth in his season? or canst thou guide Arcturus with his sons?” – Job 38:32, KJV.) One interesting story about Arcturus relates to the 1933 Century of Progress Exhibition in Chicago. Its promoters wanted a flashy way to open the show, so they decided to have the light from Arcturus pass through a telescope onto a photocell. The photocell in turn worked as the switch that turned on the main spotlights to open the exhibition.

There had also been a World’s Fair in Chicago in 1893, 40 years before the 1933 show. At the time, astronomers thought that Arcturus was 40 light-years away. So they thought that light left Arcturus at the end of the 1893 fair and traveled for 40 years through space like an Olympic torch bearer, to open the 1933 show. The promoters of Chicago’s World’s Fair had a great idea, but today’s astronomers place the distance to Arcturus at just less than 37 light-years . The position of Arcturus is RA: 14h 15 m 39.7s, dec: +19° 10′ 56″. Boötes Boötes Visible between latitudes 90 and -50 degrees Best seen in June (at 9:00 PM) Named Stars Asellus Tertius (Kappa 2 Boo) Alkalurops (Mu 1 Boo) Merga (38 Boo) Some say that Boötes is the most ancient constellation in the sky.

Indeed, it has been reconized by numerous cultures in slightly different forms. Even the Greeks were not clear on its history. The first reference to the name Boötes comes from "The Odyssey" by Homer almost three millenia ago. In one of his most popular incarnations, he is called the Hunter and, with his Hounds ( Canes Venatici ), he eternally circles the Bears, Ursa Major and Ursa Minor , around the North Pole. In fact, the brightest star in Boötes is Arcturus, which can be loosely translated as "Bear Guard." He is also called the Herdsman and his journey around the pole represents his task of keeping the celestial beasts together. Another legend says that Bootes was the son of Zeus and Callisto. Hera changed Callisto into a bear who was almost killed by Boötes when he was out hunting. Luckily, she was rescued by Zeus and he took her into the sky where she is now Ursa Major, the Great Bear. Yet another myth says that he was the son of Demeter, the goddess of agriculture. Supposedly he was given a place in the sky for inventing the plow.

BOOTES BOOTES Pages where BOOTES is discussed in Chet Raymo 's 365 Starry Nights: 79,93-100 What is the Genitive form? What is Right Ascension (RA)? Is this constellation ever visible from my latitude? What is Declination ? Where should I look for a constellation on a date before or after its midnight culmination? What is Midnight Culmination ? Skylore One of the oldest constellations, mentioned in Homer's Odyssey. Description Skywatchers have long-repeated the catch-phrase "Arc to Arcturus" (Arc-TUR-us). Follow the curve of the Big Dipper's handle to the fourth brightest star in the sky. Arcturus belongs to the ancient constellation Bootes (BOW-oh-tees). Look for a pentagon above Arcturus forming the torso of the herdsman. Some prefer to see Bootes as a one-scoop ice cream cone. Just to one side lies Corona Borealis , the Northern Crown. With bright Gemma ("Jemma") in its center, like a second scoop of ice cream that melted in the heat of summer and fell off the top.

In March of 1996 many North Americans observed the comet Hyakutake (YAH-koo-TAH-kee). When first visible, Hyakutake was near Arcturus, and from night to night it gradually passed between the Dippers before falling below our horizon at the end of April. Legend: In the constellation chart above... Star colors represent their spectral types (even for double stars). Bright star labels are yellow; significant other stars are labelled in magenta. The size of each star indicates its relative magnitude . Constellation names are light blue. Grid lines represent either 10 degree intervals of declination above or below the equator, or intervals of one hour (=15 degrees) of right ascension (measured along the equator). Messier object numbers are pink. Galaxies are ovals: blue if spiral, yellow if elliptical, light blue if irregular. Globular clusters are gold starbursts. Open clusters are dotted white circles. Planetary nebula are green diamonds. Bright nebula are magenta squares. Dark nebula are grey rectangles. Green x's are x-ray sources. Purple O's with a diagonal slash through them are quasars.

Star chart created with Voyager II Software for Macintosh, published by Carina Software. This is just a taste of what Voyager can do! For info on Voyager II software, call Carina Software at (510) 355-1266, write them at 12919 Alcosta Blvd Suite #7, San Ramon, CA 94583, or visit Carina Software's home page and check out Voyager II for yourself. Asterisms What is an Asterism ? Special Stars Arcturus means "guardian of the bear." It is an orange giant over 20 times brighter than the sun, the brightest in the northern hemisphere. Arcturus was the first star to be observed in the daytime, in 1635. Arcturus moves across the sky against the background of the other stars. This "proper" motion was discovered by Edmond Halley in 1717, and shows that the so-called fixed stars are not completely fixed in their relative positions. You can't see Arcturus move on any given night, but it is slowly passing by the Sun, and is scheduled to disappear from our sky in just half a million years.

;-) Starstruck Tonight ©1997 Welcome to the Basic Celestial Phenomena web site. To provide explanations of basic observational astronomy to students, teachers, families, and visitors to planetariums these pages have been written by an ex-OBU Planetarium Director, Kerry Magruder; the OBU Natural Sciences Coordinator, Mike Keas; and some of the students who work in the OBU planetarium. The source for the logo is not a medieval woodcut! These web pages may be printed, copied, and distributed for educational use by any non-profit educational group so long as they are not edited or altered in any way, nor distributed for profit, nor repackaged or incorporated into any other medium or product, and so long as full credit is given to Kerry Magruder. If you find a link that does not work, please tell us which link does not work--and which page you are on. Contact us by Email with general inquiries or suggestions. Thank you. The Constellation Boötes - Universe Today Universe Today by Tammy Plotner Welcome back to Constellation Friday! Today, in honor of our dear friend and contributor, Tammy Plotner, we examine the Bootes constellation. Enjoy!

In the 2nd century CE, Greek-Egyptian astronomer Claudius Ptolemaeus (aka. Ptolemy) compiled a list of the then-known 48 constellations. Until the development of modern astronomy, his treatise (known as the Almagest ) would serve as the authoritative source of astronomy. This list has since come to be expanded to include the 88 constellation that are recognized by the International Astronomical Union (IAU) today. The constellation Boötes (pronounced Bu-Oh-Tays) is one of these constellations, and was also among those listed in the Almagest. It is frequently called the “Watcher of the Bear”, guarding over the northern constellations of both Ursa Major and Ursa Minor (the Greater and Lesser Bears). It is bordered by Canes Venatici, Coma Berenices, Corona Borealis, Draco, Hercules, Serpens Caput, Virgo and Ursa Major. Name and Meaning: According to myth, Boötes is credited for inventing the plough, which prompted the goddess Ceres – a goddess of agriculture, grain crops, fertility and motherly love – to place him in the heavens.

There are also versions where Bootes represents a form of Atlas, holding up the weight of the world as it turns on its axis (yet another of Hercules’ labors). Most commonly, Boötes is taken to represent Arcas, the son of Zeus and Callisto. In this source, Arcas was brought up by Callisto father, the Arcadian king Lycaon. One day, Lycaon decided to test Zeus by serving him his own son for a meal. Zeus saw through Lycaon’s intentions and transformed the king into a wolf, killed his sons, and brought Arcas back to life. Boötes as depicted in Urania’s Mirror, a set of constellation cards published in London c.1825. Credit: Wikipedia Commons/Sidney Having heard of her husband’s infidelity, Zeus’ wife Hera transformed Callisto into a bear. For years, she roamed the woods until she met her son, who was now grown up. Arcas didn’t recognize his mother and began to chase her. To avoid a tragic end, Zeus intervened by placing them both in the sky, where Callisto became Ursa Major (aka.

The Big Dipper , or “Great Bear”) and Arcas became Boötes. In another story, Boötes is taken to represent Icarius, a grape grower who was given the secret of wine-making by Dionysus. Icarius used this to create a wonderful wine that he shared with all his neighbors. After overindulging, they woke up the next day with terrible hangovers and believed Icarius had tried to poison them. They killed him in his sleep, and a saddened Dionysus placed his friend among the stars. Notable Features: Bootes contains the third brightest star in the night sky – Arcturus (aka. alpha Boötis) – whose Greek name “Arktos” also means “bear”, and is associated with all things northern (including the aurora). Arcturus is quite important, being a type K1.5 IIIpe red giant star. The letters “pe” stand for “peculiar emission,” which indicates the spectrum of the star is unusual and full of emission lines. This is not uncommon in red giants, but Arcturus is particularly strong. The location of the Bootes contellation.

Credit: IAU/Sky and Telescope Arcturus is about 110 times more luminous than our nearest star, but the total power output is about 180 times that of the Sun (when infrared radiation is considered). Arcturus is also notable for its high proper motion, larger than any first magnitude star in the stellar neighborhood other than Alpha Centauri. It is now almost at its closest and is moving rapidly (122 km/s) relative to the Solar System. Arcturus is also thought to be an old disk star, and appears to be moving with a group of 52 others of its type. Its mass is hard to determine exactly, but it may have the same mass as Sol, or perhaps 1.5 times as much. Arcturus may also be older than the Sun, and much like what the Sun will be in its Red Giant Phase . Arcturus achieved fame when its light was used to open the 1933 Chicago World’s Fair. The star was chosen because it was thought that light from the star had started its journey at about the same time of the previous Chicago World’s Fair (1893).

Technically the star is 36.7 light years away, so the light would have started its journey in 1896. Arcturus’ light was still focused onto a cell that powered the switch for the lights that eventually shined so bright that Arcturus was no longer visible. Arcturus, along with its neighboring stars, also form the curious “Colonial Viper” formation, a triangular asterism invented by dedicated SkyWatcher, Ed Murray. It is so-named because it resembles a Colonial Viper being launched from a tube on the TV series Battlestar Galactica. The “Launch Tube” is formed by the intersection of Arcturus, Alphekka (Alpha Corona Borealis) and Gamma Bootis, while Izar (Epsilon Bootes) is the Viper. A Colonial Viper leaving the Launch Tube aboard the Battlestar Galactica. Credit: battlestararies-bsr26.net Other notable stars include Nekkar (Beta Boötis), a yellow G-type giant that is 219 light years from Earth. It is a flare star, which is a type of variable star that shows dramatic increases in luminosity for a few minutes.

The name Nekkar derives from the Arabic word for “cattle driver”. Then there’s Seginus (Gamma Boötis), a Delta-Scuti type variable star that is approximately 85 light years from Earth. It shows variations in its brightness due to both radial and non-radial pulsations on its surface. Izar (Epislon Boötis) is a binary star located approximately 300 light years away which consists of a bright orange giant and a smaller and fainter main sequence star. Epsilon Boötis is also sometimes knows as Pulcherrima, which means “the lovieliest” in Latin. The name Izar comes from the Arabic word for “veil.” The star’s other traditional names are Mirak (“the loins” in Arabic) and Mizar. Muphrid (Eta Boötis) is a spectroscopic binary star that is 37 light years from Earth and close to Arcturus in the sky. The star’s traditional name is Muphrid, derived from the Arabic phrase for “the single one of the lancer.” It belongs to the spectral class G0 IV and has a significant excess of elements heavier than hydrogen.

Boötes is also home to many Deep Sky Objects. This includes the Boötes void (aka. the Great Void, the Supervoid). This sphere-shaped region of the sky is almost 250 million light years in diameter and contains 60 galaxies. The void was originally discovered by Robert P. Kirshner – a Harvard College Professor of Astronomy – in 1981, as part of a survey of galactic redshifts. The very loose globular cluster NGC 5466 located in the Boots consetllation, Credit: NASA, ESA/Wikisky Then there is the Boötes Dwarf Galaxy (Boötes I), a dwarf spheroidal galaxy located approximately 197,000 light years from Earth that measures about 720 light years across. It was only discovered in 2006, owing to the fact that it is one of the faintest galaxies known (with an absolute magnitude of -5.8 and apparent magnitude of 13.1). Boötes I orbits the Milky Way and is believed to be tidally disrupted by its gravity, as evidenced by its shape.

And there’s also NGC 5466, a globular cluster approximately 51,800 light years from Earth and 52,800 light years from the Galactic center. The cluster was first discovered by the German-born British astronomer William Herschel in 1784. It is believed that this cluster is the source of a star stream called the 45 Degree Tidal Stream, which was discovered in 2006. History of Observation: The earliest recorded mentions of the stars associated with Boötes come from ancient Babylonia, where it was listed as SHU.PA. These stars were apparently depicted as the god Enlil, who was the leader of the Babylonian pantheon and special patron of farmers. It is likely that this is the source of mythological representations of Bootes as “the ploughman” in Greco-Roman astronomy. The name Boötes was first used by Homer in The Odyssey as a celestial reference point for navigation. The name literally means “ox-driver” or “herdsman”, and the ancient Greeks saw the asterism now called the “Big Dipper” or “Plough” as a cart with oxen.

His dogs, Chara and Asterion, were represented by the constellation of Canes Venatici (the Hunting Dogs) who drove the oxen on and kept the wheels of the sky turning. The Big Dipper, the asterism that neighbors the Bootes constellation. Credit: Jerry Lodriguss In traditional Chinese astronomy, many of the stars in Boötes were associated with different Chinese constellations. Arcturus was one of the most prominent, variously designated as the celestial king’s throne (Tian Wang) or the Blue Dragon’s horn (Daijiao). Arcturus was also very important in Chinese celestial mythology because it is the brightest star in the northern sky, and marked the beginning of the lunar calendar. Flanking Daijiao were the constellations of Yousheti on the right and Zuosheti on the left, which represented the companions that orchestrated the seasons. Dixi, the Emperor’s ceremonial banquet mat, was north of Arcturus. Another northern constellation was Qigong, the Seven Dukes, which was mostly across the Boötes-Hercules border. The other Chinese constellations made up of the stars of Boötes existed in the modern constellation’s north.

These are all representations of weapons – Tianqiang, the spear; Genghe, variously representing a lance or shield; Xuange, the halberd; and Zhaoyao, either the sword or the spear. Finding Bootes: Bootes can be found south of Ursa Major, just off the handle of the Big Dipper. Because the Big Dipper is easy for most observers to find, the handle is used to point to other important stars. Bootes’ brightest star, Arcturus, is also part of a mnemonic device used to orient people, which goes: “Arc to Arcturus, speed on to Spica.” This means you follow the curve in the Dipper’s handle away from Ursa Major until you run into Arcturus. The other star – Spica – is part of the neighboring Virgo constellation . Arcturus, the brightest star in the Boötes constellation. Credit: astropixels.com For those using binoculars, check out Tau Bootis, a yellow-white dwarf approximately 51 light-years from Earth. It is a binary star system, with the secondary star being a red dwarf.

In 1999, an extrasolar planet was confirmed to be orbiting the primary star by a team of astronomers led by Geoff Marcy and R. Paul Butler. Maybe you’d like to look at long term variable star R Boötis? It ranges from 6.2 to 13.1 every 223.4 days. For those using telescopes, there are plenty of excellent binary star systems to be seen. Pi Boötis is located approximately 317 light years from our solar system and the primary component, P¹ Boötis, is a blue-white B-type main sequence dwarf with an apparent magnitude of +4.49. It’s companion, P² Boötis, is a white A-type main sequence dwarf with an apparent magnitude of +5.88. Now try looking at Xi Boötis, a binary star system which lies 21.8 light years away. The primary star, Xi Boötis A, is a BY Draconis variable, yellow G-type main sequence dwarf with an apparent magnitude that varies from +4.52 to +4.67. with a period just over 10 days long.

Small velocity changes in the orbit of the companion star, Xi Boötis B – an orange K-type main sequence dwarf – indicate the presence of a small companion with less than nine times the mass of Jupiter. The AB binary can be resolved even through smaller telescopes. The primary star (A) has been identified as a candidate for possessing a Kuiper-like belt, based on infrared observations. The estimated minimum mass of this dust disk is 2.4 times the mass of the Earth’s Moon. The location of Mu Bootis (Alkalurops) in the Bootes constellation. Credit: universeguide.com Then there’s the triple system, Mu Boötis. The primary component, Mu¹ Boötis, is a yellow-white F-type sub giant with an apparent magnitude of +4.31. Separated from the primary by 108 arc seconds is the binary star Mu² Boötis, which has a combined spectral type of G1V and a combined brightness of +6.51 magnitudes. The components of Mu² Boötis have apparent magnitudes of +7.2 and +7.8 and are separated by 2.2 arc seconds.

They complete one orbit about their common center of mass every 260 years. How about colorful yellow and blue Kappa Boötis? Kappa2 Boötis is classified as a Delta Scuti type variable star and its brightness varies from magnitude +4.50 to +4.58 with a period of 1.83 hours. The companion star, Kappa¹ Boötis, has magnitude +6.58 and spectral class F1V. For deep sky observers with large telescopes, try checking out the globular cluster NGC 5466, which is about a fist’s width north of Arcturus. This class XII, 9th magnitude globular was discovered in 1784 by Sir William Herschel and presents an nice challenge for experienced stargazers and amateur astronomers. Or try compact spiral galaxy NGC 5248. It’s about a fist width south of Arcturus and about a finger width southwest. It’s part of the Virgo cluster of galaxies and could be as far as 50 million light years away. It’s another great grand design spiral which shows spiral galaxy structure when viewed in long exposure photographs.

You can mark it on your list as Caldwell 45. The NGC 5248 spiral galaxy, as imaged with a 32-inch telescope. Credit and Copyright: Adam Block/Mount Lemmon SkyCenter/University of Arizona But if you’d just like to have some fun, then why not try picking out the aforementioned “Colonial Viper and Launch Tube” asterism. If you’re a longstanding Battlestar Galactica fan, then you’ll recognize this ultra-cool spaceship as it sits in its triangular shaped launch tube. To find it, just draw a line between Arcturus, Alphekka (Alpha Corona Borealis) and Gamma Bootis which make up the “Launch Tube”, while Izar (Epsilon Bootes) is the Viper. We have written many interesting articles about the constellation here at Universe Today. Here is What Are The Constellations? , What Is The Zodiac? , and Zodiac Signs And Their Dates . Be sure to check out The Messier Catalog while you’re at it! For more information, check out the IAUs list of Constellations, and the Students for the Exploration and Development of Space page on Bootes and Constellation Families .

Share this: Sirius is Dog Star and brightest star | Brightest Stars | EarthSky Sirius is Dog Star and brightest star By Deborah Byrd in Brightest Stars | Science Wire | February 10, 2016 Sirius – in the constellation Canis Major the Greater Dog – is the sky’s brightest star. It’s very easy to spot on winter and spring evenings. The star Sirius and the nearby star cluster M41 caught on January 2, 2016 in Weatherly, Pennsylvania. Photo by Tom Wildoner at LeisurelyScientist.com The brightest star visible from any part of Earth is Sirius in the constellation Canis Major the Greater Dog. Sirius is sometimes called the Dog Star. Follow the links below to learn more about Sirius, the Dog Star and brightest star. The Greater Dog looking super cute in this photo Tom Wildoner ! Brightest star is Sirius. Orion’s Belt points to Sirius How to see Sirius. Most people in the Northern Hemisphere notice Sirius in the southeast – south – or southwest on evenings from winter to mid-spring. February evenings are a grand time to see it. It’s also fun to spot Sirius as it ascends in the east before dawn on late summer mornings.

Whenever you see Sirius, you’ll recognize it easily because it is our sky’s brightest star. Although white to blue white in color, Sirius might be called a rainbow star, as it often flickers with many colors. The brightness, twinkling and color changes sometimes prompt first-time observers to report Sirius as a UFO. But these changes have nothing to do with Sirius. Rather, they are what happens when such a bright star as Sirius shines through the blanket of Earth’s atmosphere. The light from Sirius, which often appears fairly low in the sky from the mid-north latitudes, passes through a long column of air before it reaches our eyes. Changes in density and temperature of this air affect the light and cause the flickering and shimmering we see when we gaze at this star. This happens for other stars, too, but it is more noticeable for Sirius because it is so bright, and because it appears low in the sky. From the mid-northern latitudes such as most of the U.S., Sirius rises in the southeast, arcs across the southern sky, and sets in the southwest. In December, you’ll find Sirius rising in mid-evening. By mid-April, Sirius is setting in the southwest in mid-evening.

Sirius is always easy to find. It’s the sky’s brightest star! Plus, anyone familiar with the constellation Orion can simply draw a line through Orion’s Belt, to the left. This line will point to Sirius, which is roughly 8 times as far from the Belt as the Belt is wide. The Egyptian god Osiris History and mythology of Sirius. Sirius is also well known as the Dog Star, because it is the chief star in the constellation Canis Major, the Big Dog. Have you ever heard anyone speak of the dog days of summer? Sirius is behind the sun as seen from Earth in Northern Hemisphere summer. In late summer, it appears in the east before sunrise – near the sun in our sky. The early stargazers might have imagined that the double-whammy of Sirius and the sun caused the hot weather, or dog days. Sirius has been known since ancient times, and its name signified its nature as “scorching” or “sparkling.” It was associated with the Egyptian god Osiris and other gods. Ancient Egyptians noted that Sirius rose just before the sun each year immediately prior to the annual flooding of the Nile River. Although the floods could bring destruction, they also brought new soil and new life.

Fittingly, Osiris, whom Sirius may have represented, was a god of life, death, fertility and rebirth of plant life along the Nile. In India, Sirius is sometimes known as Svana, the dog of Prince Yudhistira. The prince and his four brothers, along with Svana, set out on a long and arduous journey to find the kingdom of heaven. However, one by one the brothers all abandoned the search until only Yudhistira and Svana were left. At long last they came to the gates of heaven. The gatekeeper, Lord Indra, welcomed the prince but denied Svana entrance. Yudhistira was aghast and told Lord Indra that he could not forsake his good and faithful servant and friend. His brothers, Yudhistira told the Lord, had abandoned the journey to heaven to follow their hearts’ desires. But Svana, who had given his heart freely, chose to follow none but Yudhistira. The prince told the Lord that without his dog, he would forsake even heaven. This is what Lord Indra had wanted to hear, and then he welcomed both the prince and the dog through the gates of heaven.

This Hubble Space Telescope image shows Sirius A, the brightest star in our night sky, along with Sirius B, its faint, tiny stellar companion. Sirius B is the faint, tiny dot at the lower left. Sir. Image credit: H. Bond (STScI) and M. Barstow (University of Leicester) Sirius science. Magnitude is a star’s brightness expressed by a number. The smaller the number, the brighter the star. The visual magnitude of Sirius is -1.44, lower than any other star. It is 3.5 times brighter than Arcturus in Bootes, the next brightest star easily visible from the northern hemisphere. There are brighter stars in terms of actual energy and light output, but they are farther away and hence dimmer. Normally, the only objects that outshine Sirius in our heavens are the sun, moon, Venus, Jupiter, Mars and Mercury (and usually Sirius outshines the latter two!). The next brightest star (Canopus) after Sirius, and the closest major star (Alpha Centauri) are both too far south in the sky to be easily seen from mid-north latitudes.

At 8.6 light-years distance, Sirius is one of the nearest stars to us after the sun. (A light year is nearly 6 trillion miles!) In fact it is the nearest star easily visible to the unaided eye from most of the northern hemisphere. Classified by astronomers as an “A” type star, it is much hotter than our sun, with about surface about 17,000 degrees F (the sun is about 10,000 degrees F). With slightly more than twice the mass of the sun and just less than twice its diameter, Sirius still puts out 26 times as much energy. It is considered a normal (main sequence) star, meaning that it produces most of its energy by converting hydrogen into helium through nuclear fusion. Sirius has a small, faint companion star appropriately called The Pup. That name signifies youth, but in fact the companion to Sirius is a dead star called a white dwarf. Once a mighty star, today The Pup is an Earth-sized ember too faint to be seen without a telescope. The position of Sirius is RA: 06h 45m 08.9s, dec:-16° 42′ 58″.

Image Credit: Yuuji Kitahara Northern Rockies Skies for July: The Constellation Bootes, the Herdsman | News | University of Wyoming Northern Rockies Skies for July: The Constellation Bootes, the Herdsman June 27, 2013 A monthly look at the night skies of the northern Rocky Mountains, written by astronomers Ron Canterna, University of Wyoming; Jay Norris, Challis, Idaho Observatory; and Daryl Macomb, Boise State University. Immediately after sunset, almost directly overhead, the third brightest individual star in the night skies appears, the orangish giant Arcturus. Arcturus is the first bright star on the imaginary arc from the handle of the Big Dipper to the star, Spica, in Virgo. Arcturus also is the brightest star in the Herdsman, the constellation Bootes. As the mythological story goes, the herdsman drives the oxen cart of Ursa Major around the celestial pole, accompanied by his two companion hunting dogs, Canes Venatici, located slightly to the west. Mythology tells us that it is the herdsman that keeps the night skies in a constant rotation around Polaris.

Arcturus, the “guardian of the bear,” is an individual orange giant with a surface temperature that is slightly cooler than our sun’s. Although Arcturus is nearly 40 light years from the sun, it is about 10 times larger than the sun and gives off more than 100 times more energy, making it one of the brightest stars in the sky. July planet watch: Venus, the brightest object in the night, will be on the western horizon after sunset. Saturn will be located near Spica (Virgo) just south of Bootes. Astronomy from Orbit: Gamma-ray Bursts – BATSE (Best URL: ) Up through the 1980s, gamma-ray burst (GRB) space instruments that formed the Interplanetary Network continued to record many GRBs. However, there were still insufficient detections to determine if the burst sources were among the nearest stars, or if they were detected from as far out as the edges of our Milky Way galaxy or, perhaps, even from far beyond our galaxy. The larger the distances of GRB sources, the more energetic they would have to be.

Therefore, most GRB researchers in the 1980s believed the GRB sources to be in the galaxy and, that if enough could be detected, the GRB distribution on the sky would track the planar distribution of the Milky Way itself. During this time period, the Gamma Ray Observatory (GRO) -- the second of NASA’s “Great Observatories”--was being planned, and researchers had convinced NASA to include a GRB instrument onboard. It was named the Burst and Transient Source Experiment (BATSE) and led by the Marshall Space Flight Center. GRO itself was the size of a step van, and weighed about 37,000 pounds, with a good portion of the weight being in the large sodium or cesium iodide crystals that are used to detect gamma rays. The geometry of the BATSE experiment was distributed as eight large (20-inch diameter) sodium iodide detectors situated on the eight corners of the roughly rectangular-solid GRO satellite. With this arrangement, the detectors covered the whole sky (and the Earth).

After launch in April 1991, GRO was named for Arthur Compton, who received the 1927 Nobel Prize in physics for elucidating the scattering of high-energy photons with electrons. When two or more BATSE detectors “triggered” an increase in the gamma-ray rate, onboard circuits began recording the event, subsequently sending the recorded GRB information to the ground for analysis. During the nine-year span of the GRO mission, BATSE detected more than 2,700 bursts, about one per day. The surprise was that the distribution of burst positions on the sky was uniform -- so uniform that the Milky Way and our sister galaxy, Andromeda, were effectively eliminated as the sources of GRBs. Instead, the weight of the evidence from BATSE suggested that bursts came from very large distances, from the far reaches of the universe. Toward the end of the Compton GRO mission, this new hypothesis was confirmed via observations from additional satellites and ground-based observatories -- to be discussed next time. To view this month’s sky chart, click here . Photo: The Compton GRO satellite being deployed by the Space Shuttle. Four BATSE modules are visible on corners of the satellite’s top side.

Share This Page: Transit Date of principal star: 26 April Bo�tes may be a hunter, on the tracks of the Great Bear, accompanied by his two dogs Asterion and Chara (the constellation "Canes Venatici"). The constellation was once known as Arctophylax which means the protector of the Bear. Yet the name itself, Bo�tes, comes from the Greek, as first mentioned in Homer, and means 'ox-driver'. The � is called a diaeresis, and indicates that each 'o' is to be pronounced. The Romans called him Venator Ursae: the Bear Hunter. Nowadays Bo�tes is sometimes considered to be a Herdsman (as in French: Le Bouvier), as he eternally shepherds the stars around the North Pole. As mentioned above, the first recorded appearance of Bo�tis is found in Homer's Odyssey. In Book V Odysseus sails his ship by the stars, using the Pleiades, the Bear, and Bo�tes ("which set late") to reach his destination. The constellation forms a bright naked eye display, and is quite compact, squeezed between Canes Venatici and Hercules, with Virgo to the south.

The northern border touches both Ursa Major and Draco. There is a full complement of Bayer stars . To find the major star, Arcturus, follow the sweep of the Big Dipper's handle. These stars lead to the brightest star in the northern hemisphere, and the fourth brightest in all of the heavens: alpha Bo�tis, better known as Arcturus. Arcturus means "Guardian of the Bear". This orange-red giant is about 20-25 times the size of the Sun, with about the same mass. In fact the Sun will probably take the same path, eventually ballooning to the same size in another five billion years. The star has an unusually high proper motion (2.281") and a space velocity of 118 km/sec. It is 35.4 light years away. Some constellations are known for their deep sky objects; others for an interesting variable or perhaps an attractive binary. Bo�tes has few deep sky objects of any interest. Nor are its variables particularly noteworthy. However the constellation does have one of the finest collection of double stars, some of which are described below.

Double stars in Bo�tes: Zeta Bo�tis is a very fast binary with a highly eccentric orbit of 123.4 years. The companion is currently fairly close (0.9") at PA 301�. Epsilon Bo�tis was one of Struve's favourite double star systems: 2.5, 4.9; a bright yellow primary with a blue-green companion. The orbit is so large it may as well be considered fixed: PA 339�, separation 2.8". Kappa Bo�tis is a gorgeous double with colour contrast; the primary is yellow and the companion a deep blue. The binary is fixed at PA 235�, separation 13.4". In the same field is iota Bo�tis: 4.9, 7.5; PA 33�, separation 38.5" Mu Bo�tis is a triple system. AB are fixed: 4.3, 7.0; PA 171�, separation 108".

The component B has a close companion C (magnitude 7.6) which is a rapid binary, with an orbit of 246.1 years. The 2000 values are PA 7�, separation 2.1". Pi Bo�tis is a pleasant binary of two blue-white stars (4.9, 5.8; PA 108�, separation 5.6"). Xi Bo�tis is a rapid binary (4.7, 7.0) with orbit of 151 years. The primary is yellow, and the companion a white-pink. Currently the companion is found at PA 321� and 6.8" separation. Struve 1785 is another attractive rapid binary, with orbit of 155 years. The companion can now be found at PA 173�, 3.3" separation. Struve 1909 (44 Boo) is yet another rapid double, with an orbit of 225 years. In the year 2000 the companion will be at its widest separation for the next fifty years.

Presently it's located at 54�, 2.2" separation. Variable stars in Bo�tes: The constellation contains three delta Scuti type variables: gamma, iota, and kappa2. Delta Scuti variables are fairly young stars which pulsate, creating a slight variation in visual magnitude, less than 0.5 magnitude and often considerably less than this, with a short period (from 30 minutes to about eight hours). Thus the stars, while quite numerous, are not of the kind which amateur enthusiasts tend to study. R Bo�tis is a long-period variable with a range from 6.2 to 13.1 every 223.4 days. In 2000 the maximum is scheduled to appear in early April. Deep Sky Objects in Bo�tes: There are no Messier objects in this constellation, but for the inveterate deep sky observer there are still a few nice galaxies. Below are two of the better deep sky objects. NGC 5248 is a very compact spiral galaxy in the southwestern corner of the constellation, ten degrees south of Arcturus and one and a half degrees west.

(Two degrees north is the rapid binary BU 612 (6.3, 6.3) with period 22.4 years.) NGC 5466 is a large but quite dim globular cluster. It's found nine degrees north of Arcturus and one and a half degrees west. (The Messier object M3 is five degrees due west in Canes Venatici.) For a closer appreciation of Bo�tes, visit the Binocular Section. Return to the previous page: Or go to Arcturus ARCTURUS (Alpha Bootis). Among the very brightest of stars, shining with a soft orange light, Arcturus lights northern spring skies. It is one of three luminaries that partition the northern sky into very rough thirds, the others being summer's Vega and winter's Capella . Of the three, Arcturus, the Alpha star of the constellation Bootes , the Herdsman, is slightly the brighter, making it the brightest star of the northern hemisphere and the fourth brightest star of the entire sky, following only Sirius , Canopus , and Alpha Centauri .

Arcturus, the "Bear Watcher," follows Ursa Major , the Great Bear, around the pole, "arktos" being the Greek name for "bear," from which our word "arctic" is derived by reference with the constellation of the Greater Bear. Arcturus is located at a distance of 37 light years, and became famous when its light was used to open the 1933 world's fair in Chicago, as that light had left the star at about the time of the previous Chicago fair in 1893. It is a classic orange class K (K1) giant star with a precisely defined surface temperature of 4290 degrees Kelvin. To the eye, it shines 113 times more brightly than our Sun . Its lower temperature, however, causes it to radiate considerable energy in the infrared. When this infrared radiation is taken into account, Arcturus actually shines almost twice as brightly, releasing 215 times more radiation than our Sun, from which we find a diameter 26 times solar, about a quarter the size of Mercury's orbit.

Arcturus is close and large enough so that its angular diameter of 0.0210 seconds of arc can easily be measured, leading to a very similar direct determination of 25 times the solar dimension and providing nice confirmation of stellar parameters. Arcturus has a velocity relative to the Sun that is higher than other bright stars. Compared with the set of surrounding stars, which orbit the Galaxy on more or less circular orbits, it falls behind by about 100 kilometers per second (as do several others of the "Arcturus Group"). The lagging movement has long suggested that the star comes from an older population of the Galaxy. Consistently, it is somewhat deficient in metals, having only about 20 percent as much iron relative to hydrogen as found in the Sun. A more intriguing suggestion is that the star actually comes to us from a small galaxy that merged with ours some 5 to 8 billion years ago. As a giant, weighing in at around 1.5 times the mass of the Sun, it has ceased the fusion of hydrogen in its core. Though it is somewhat brighter than we would expect for a stable helium fusing star, helium fusion to carbon has probably already begun.

Such stars are not expected to have magnetic activity like the Sun, but very weak X-ray emission suggests that Arcturus indeed is magnetically active and has a hard-to-observe "buried corona."

Question: Which is the brightest star in the northern constellation of Bootes?
Answer: ARCTURUS