Boots

Bootes or the Mountain Dog is one of the 88 modern constellations and was one of the 48 constellations listed by Ptolemy. Bootes appears to be a large human figure, facing the Big Dipper.

Notable features

Boot constellation

Arthur (α Bootis) is the constellation's brightest star and the third brightest in the night sky. It is an orange giant of spectral type K1.5III whose radius is 26 times greater than the solar radius. Distant 36.7 light years from the solar system, it is the second closest giant star to the solar system after Pollux (β Geminorum). Arthur's relative velocity with respect to the Sun, as well as its low metallicity—approximately 28% of solar—suggest that it may be an old Population II star and a member of the thick galactic disk.

After Arthur, Izar (ε Bootis) is the brightest star in Bootes. It is one of the most beautiful binary stars in the sky, being called Pulcherrima ("the most beautiful") by the astronomer Friedrich Georg Wilhelm von Struve when he observed the beautiful contrast between its two components, a luminous orange giant and a white star of the sequence major. It has an orbital period of more than 1,000 years.

The third brightest star is η Bootis, named Muphrid, a yellow subgiant of type G0IV and a spectroscopic binary. The companion star has an orbital period of 494 days and may be a red dwarf of type M7 or later. This star system is 37 light-years away, its high metallicity being remarkable, almost twice that of the Sun. Nekkar (β Bootis) is a yellow giant of spectral type G8IIIa with a diameter 21 times that of the Sun; with an effective temperature of 4940 K, it is 150 times more luminous than the Sun. Of similar brightness to the latter, δ Bootis is also a G8III type giant closer to but less luminous than Nekkar. Somewhat cooler, ψ Bootis is an orange giant of spectral type K2III.

Xuange —official name of λ Bootis— is a chemically peculiar star for whose anomalous composition there is still no clear explanation today. While the outer layers of the star are depleted of metals such as chromium, barium, nickel, and titanium, the content of other elements is normal.

Asellus Primus (θ Bootis) is a yellow dwarf of type F7V somewhat more massive, hotter, and luminous than our Sun. Very similar is τ Bootis, a star where a "hot Jupiter" type planet has been discovered. Both stars have a red dwarf companion as a companion and are located about 50 light-years from the solar system.

Alkalurops (μ Bootis) is a stellar system whose main component is a subgiant of type F0IV 23 times more luminous than the Sun; the other component of the system is, in turn, a binary formed by two solar analogues of type G1V. Another star of interest is 44 Bootis (i Bootis), a triple stellar system where two of its components —one of them a yellow dwarf less luminous than the Sun— form a contact binary, that is, they are so close to each other that they share the photosphere, although each one of them has a differentiated nucleus. They move in a circular orbit that they complete every 6,427 hours.

Among the variables of the constellation are V Bootis —a pulsating star with two simultaneous pulsation modes, one with an approximate period of 258 days and the other of 134 days— and W Bootis —a red giant of type M3III and a semiregular variable whose brightness fluctuates between magnitude +4.73 and +5.40— Also worthy of attention is RX Bootis, a cold red giant of type M7.5III where the existence of a water vapor maser has been detected. The total extent of the maser envelope is 12 - 18 au. Two other red giants, both irregular variables, are BY Bootis and CF Bootis. The first has type M4.5III and its diameter is more than 100 times greater than the solar diameter.

Image of NGC 5248 obtained with Hubble Space Telescope

In addition to Tau Bootis, the constellation contains several planetary systems. One notable system is HD 141399, a K0-type star more massive than the Sun that has four planets. HD 128311 is an orange dwarf with two planets separated from its star by 1.1 and 1.8 au respectively. Also, TVLM513-46546 is an "ultracool" red dwarf where a planet comparable to Saturn has been discovered.

HP Bootis is a BY Draconis variable of type G2V, very similar to the Sun, gravitationally linked to two brown dwarfs. Similarly, CE Bootis is a red dwarf orbited by a system made up of at least two brown dwarfs. The orbital period of the brown dwarf pair around CE Bootis is approximately 500 years.

Bootes contains the globular cluster NGC 5466, visual magnitude 9.1 and 11 arcminutes in diameter, located 51,800 light-years from Earth. It also comprises two bright galaxies. The first, NGC 5248, is an intermediate spiral galaxy that is a member of the Virgo Cluster and 59 million light-years away. The second, NGC 5676, is remarkably asymmetrical; the spiral arms on the south side of the galaxy are apparently chaotic, while those on the north side are very well defined. Much closer, 197,000 light-years away, Bootes I is a satellite dwarf spheroidal galaxy of the Milky Way discovered in 2006.

In this constellation is also the Bootes Void or Great Void, a gigantic region of space with very few galaxies. With a diameter of 350 million light years, it is located about 1 billion light years from us.

Main Stars

Arthur's size compared to the Sun.

• α Bootis (Arturo or Arcturus), with magnitude -0.04, is the third brightest star in the firmament. It is an orange giant at 37 light years away whose diameter is 25 times greater than the Sun.
• β Bootis (Nekkar), yellow giant of magnitude 3,49-219 light years away from Earth.
• γ Bootis (Seginus or Ceginus), Delta Scuti variable of magnitude 3.04.
• δ Bootis (Princeps) yellow giant like Nekkar, but halfway away.
• ε Bootis (Izar or Pulcherrima), located 10° north of Arthur, is a binary star whose main component is a yellow-orange giant. With magnitude 2,35 is the second most brilliant constellation.
• γ Bootis, binary star whose components move in a very eccentric orbit.
• η Bootis (Muphrid), third brightest star of the constellation with magnitude 2.68, is a yellow subgiant.
• θ Bootis (Asellus Primus), yellow dwarf hotter than the Sun at 47 light years.
• ι Bootis (Asellus Secundus), a double star whose components, 38.6sec apart, can be solved with binoculars.
• κ Bootis (Asellus Tertius), binary star with its separate components 13,4 seconds of arc; can be solved with a small telescope.
• λ Bootis (Xuange), chemically peculiar star with abnormal contents of certain elements; it gives name to a group called Lambda Bootis stars.
• μ Bootis (Alkalurops), double star with its separate components 108 seconds of arc; one of the components is in turn a binary star.
• . Bootis is a Bayer denomination shared by two stars: ν1 Bootis, orange giant, and ν2 Bootis, white binary star. Both have equal magnitude, 5.02.
• ・ Bootis, 22 light years away, wide binary star with a 152-year orbital period.
• π Bootis, double star whose white-blue components are separated 5.8 seconds of arc.
• ρ Bootis, orange giant at 149 light years.
• σ Bootis, white-yellow star around which a hot dust disc similar to Vega has been detected.
• τ Bootis, star system with an extrasolar planet.
• /25070/ Bootis, orange giant of magnitude 4,52.
• 2 Bootis, yellow giant of magnitude 5.63.
• 12 Bootis (d Bootis), a binary star of magnitude 4,82 whose two components, only 1 second of arc, are two white-yellow subgiants.
• 18 Bootis, white-yellow subjugant of magnitude 5.40.
• 24 Bootis (g Bootis), star of the thick disc of low metallicity.
• 33 Bootis, white star of magnitude 5.40.
• 38 Bootis (Merga), a subject of magnitude 4.77.
• 44 Bootis (i Bootis), triple star system, whose B and C components form a contact binary and a W Ursae Majoris variable.
• 45 Bootis (c Bootis), white-yellow star 64 light years away.
• R Bootis, variable Look whose brightness varies between magnitude 6.0 and 13.3.
• W Bootis (34 Bootis), red and semi-regular giant whose brightness varies between magnitude +4.73 and +5.40.
• RX Bootis, red giant where a steamer of water has been detected.
• AD Bootis and CV Bootis, eclipse binaries; the first one is composed of two stars of type F and the second one by two yellow dwarfs.

TVLM 513-46546 (the red spot in the center), seen by Sloan Digital Sky Survey

• AR Bootis, contact binary and variable W Ursae Majoris.
• BP Bootis, Bp star of magnitude 5.49.
• BY Bootis, red giant and irregular variable whose brightness varies between magnitude 4,98 and 5.33.

• CE Bootis and HP Bootis, the first one red dwarf and the second one yellow dwarf, both orbited by brown dwarfs.
• From Bootis, spectroscopic binary dominated by an orange dwarf.
• GU Bootis, eclipsant binary whose components are low-mass stars.
• HD 128311 (HN Bootis), orange dwarf with two extra-solar planets.
• Gliese 526 and Gliese 552, red dwarfs; the first, at 17.7 light years of the Solar System, is the closest to this constellation.
• TVLM513-46546, very low mass red dwarf with a stellar stain covering half of its surface.

Deep Sky Objects

Image of NGC 5466 with a 32-inch telescope.

• NGC 5466. AR: 14h 05m 30.0s Dec: +28°32'00" (Epoch 2000). Glybular cluster that is visually located 9th northwest of Arthur, near M3 in Canes Venatici. It is 51 800 light years from Earth.
• NGC 5248. AR: 13h 37m 30.0s Dec: +08°53'00" (Epoca 2000). Spiral Galaxy that can be observed 10° south of Arthur. It is a galaxy with stellar outbreak of complex structure.
• NGC 5676, a highly asymmetrical galaxy whose spiral arms on the south side offer a chaotic appearance.
• Bootes I, dwarf galaxy member of the Local Group.
• The vacuum of Bootes or the Great Void. Giant and quasiespheric space region that contains very few galaxies. With a diameter of 350 million light years, or a volume of almost 236 000 Mpc³The vacuum of Bootes is one of the greatest voids known in the universe.

Mythology

Image of the constellation of Bootes in a century atlas XVI.

Exactly who Bootes was is unclear, and many versions of his story exist:

• Filomelo, son of Demeter and Yasion, and first farmer of the world according to the Greeks.^{[chuckles]required]}

• Arcade, son of Calisto and Zeus and grandson of Lycaon, who invited Zeus to a banquet and served his own grandson as food. The god recomposed the body of Arcade and turned it into the star, but according to another version after recomposing it he was given to raise a bullfighter and punished the grandfather by turning it into wolf (Lupus) and burning his mansion.

• A farmer who handled the oxen in the Osa Mayor constellation using his two dogs Chara and Asterion (from the constellation Canes Venatici). The oxen were tied to the polar axis and the action of Bootes kept the skies in constant rotation.^{[chuckles]required]}

• The inventor of the plow, which pleased Ceres, the goddess of agriculture, who asked Jupiter to give Bootes a permanent fixed installation in the heavens as a reward for what he had done.^{[chuckles]required]}

• Icario, who had learned the cultivation of the vine of the god Dioniso. Icario invited his friends to try it. They drank too much and woke up the next morning with such discomfort that they assumed that Icario had tried to poison them and for this he was killed. Dioniso placed Icario in the stars to honor him.

Text references

General references

• _ Catasterism (Καταστερισμο).
  • 8: The Boyero, Bootes, or Artofílace (,ρκτοφσλαυ; Boōtēs, Arctóphy Bodylax): Arks or Icarios of Athens.
    • Latin text in Google Books; electronic facsimile.
      • Greek text on the Internet Archive; electronic facsimile.

• HIGINO: Poetry astronomy (Astronomica).
  • 4: Boyero.
    • English text on Mary Grant's Theoi site; 1960 trad.
      • Latin text.