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Stars & Clusters

Size comparison of our Sun, a red dwarf, a brown dwarf, Jupiter & Earth. Stars with less mass than the Sun are smaller and cooler. Brown dwarfs have less than eight percent of the Sun's mass, so can't sustain nuclear fusion. These cool orbs are nearly impossible to see in visible light, but stand out when viewed in infrared. Their diameters are about the same as Jupiter’s, but they can have up to 80 times more mass and are thought to have planetary systems of their own. (Image credit: NASA)

Getting WISE About Nemesis - Astrobiology Magazine

astrobio.net

Procyon, the seventh brightest star in the sky and one of the vertices of the Winter Triangle. It's one of our nearest neighbors at just over 11 light years away in the constellation Canis Minor. Procyon is a binary star system, composed of a white main sequence star and a white dwarf star.

The nearest stars, their distances in light-years, spectral types and known planets. Only 9 of the stars within 15 light years can be seen with the unaided eye from Earth. (Credit: Karl Tate / Source: NASA)

The Nearest Stars to Earth (Infographic)

space.com

Relative star sizes and photospheric temperatures. Any planet around a red dwarf, such as the one shown here, would have to huddle close to achieve Earth-like temperatures, probably inducing tidal lock. (Credit: MPIA/V. Joergens) Mona Evans, "Do Red Dwarfs Live Forever?" www.bellaonline.c...

How many red dwarfs are there? (credit: Jonathan O'Callaghan) Mona Evans, "Do Red Dwarfs Live Forever?" www.bellaonline.c...

PSR B1509-58. The nebula is about 150 light years in size, but at the center is an incredibly dense object 12 miles in diameter, a pulsar. Its powerful magnetic field and rapid spin make it a rich X-ray source. A pulsar is a rapidly spinning neutron star, the remnant of a massive star which ended its life in a supernova explosion. (Image: Chandra X-ray Observatory)

Chandra :: Photo Album :: PSR B1509-58 :: April 3, 2009

chandra.harvard.edu

Circinus X-1, an X-ray binary. Composite imagine with X-rays in blue and radio emission in purple, overlaid on an optical field of view. This type of binary star contains a neutron star. (Image credit: X-ray: NASA/CXC/Univ. of Wisconsin-Madison/S. Heinz et al; Optical: DSS; Radio: CSIRO/ATNF/ATCA)

X-ray Binary Circinus X-1

nasa.gov

A Hubble Space Telecope picture of globular cluster IC 4499. The new observations showed that it is about 12 billion years old, contrary to previous observations showing a puzzling young age. Credit: European Space Agency and NASA

Gamma Arietis (Mesarthim). It looks like a single star, but even a small telescope shows a pair of bright white stars like two strange eyes or a pair of headlights. (Credit: Dr. F. Ringwald/Cal. State Univ. Fresno) Mona Evans, "Aries the Golden Ram" www.bellaonline.c...

What’s outside Leona’s window? | Astro Bob

astrobob.areavoices.com

The head of Aries: Hamal (α Arietis), Sheratan (β Arietis) and Messartim (γ Arietis). These are the three brightest stars of the constellation - Hamal is of the 2nd magnitude. Messartim can be seen in small telescopes as a double star. Robert Hooke in 1664 first identified it as such. (There is also a third star that orbits the pair.) Mona Evans, "Aries the Golden Ram" www.bellaonline.c...

M6: The Butterfly Cluster (Jan 6 1999) Credit: AURA, NOAO, NSF To some, the outline of the open cluster of stars M6 resembles a butterfly. M6, also known as NGC 6405, spans about 20 light-years and lies about 2,000 light years distant. M6 can best be seen in a dark sky with binoculars towards the constellation of Scorpius, coving about as much of the sky as the full moon. Like other open clusters, M6 is composed predominantly of young blue stars, although the brightest star is nearly orange.

APOD: January 6, 1999 - M6: The Butterfly Cluster

apod.nasa.gov

Cluster surrounded by clouds of interstellar gas and dust—the raw material for new star formation. The nebula, located 20,000 light-years away in the constellation Carina, contains a central cluster of huge, hot stars, called NGC 3603. - Credit: NASA, ESA, and the Hubble Heritage Team (STScI/AURA)

Size comparison of Solar System planets, the Sun, and other stars. (Credit: Dave Jarvis)

List of largest known stars - Wikipedia, the free encyclopedia

en.wikipedia.org

The arrow points to the star 2MASS J05233822-1403022. It's the smallest, faintest star that we know of. Although it's barely visible to our eyes, in infrared - that's the inset - it's brighter. (Photo: CDA Portal / 2MASS/UMass/IPAC-Caltech/NASA/NSF) Mona Evans, "Stars - Ten Facts for Kids" www.bellaonline.c...

The Smallest Star

slate.com

NGC 457, an open cluster in Cassiopeia. It's known as the Owl Cluster, or the E.T. Cluster, because it seems to have two bright eyes. (Image Credit & Copyright: Ole Nielsen) Mona Evans, "Cassiopeia the Queen", www.bellaonline.c...

Globular cluster M15 in the constellation Pegasus. It's a ball of thousands of stars and is regarded as one of the finest examples of such a cluster in the northern sky. (Credit: ESA/Hubble & NASA) Mona Evans, "Pegasus the Winged Horse" www.bellaonline.c...

Gamma Cephei A+B. (Image credit: Calar Alto) The visible star, called Gamma Cephei A, is an orange star nearly five times the radius of the Sun and coming to the end of its hydrogen fuel. It has a planet orbiting it, as well as a companion star. The other star is about half the Sun's mass, a faint red dwarf. Gamma Cephei B was known from its spectrum before it was finally imaged. ©Mona Evans, "Cepheus the King" www.bellaonline.c...

Part of the Great Nebula of Orion. Observing the nebula with binoculars or a telescope, you can see the four brightest stars of a star cluster known as The Trapezium. These are the stars that make the nebula glow. They are hot young stars, for the nebula is a stellar nursery. It contains the material and has the right conditions for forming new stars. ©Mona Evans, "Orion the Hunter" www.bellaonline.c...

Trapezium, Orion Nebula

spacetelescope.org

Locating the pole star. Whatever the orientation of the Big Dipper (Plough), find Merak and Dubhe. Follow the line of sight to the next fairly bright star. This is Polaris which is in the Little Dipper, the constellation of Ursa Minor. Mona Evans, "Polaris - 10 Fascinating Facts" www.bellaonline.c...

Orion. (Credit: Mouser) A star near the top left of the photo is faintly orange - this is Betelgeuse, a red supergiant which various in brightness. Bottom right is a blue star which is Rigel, a blue supergiant that's usually the brightest star in Orion. The belt stars are also hot blue stars. The object below the belt that seems very large is the Orion nebula. Mona Evans, "Stellar Misunderstandings" www.bellaonline.c...

Castor, which is actually a sextuple star system, can be seen as is a fine, close double star in small telescopes. (Credit: Damian Peach) Mona Evans, "Gemini - the Celestial Twins" www.bellaonline.c...

The star Castor in Gemini. You can resolve it into three stars in a small telescope, but each of the stars has a companion. Castor is really a sextuple star system. (The diagram is not to scale.)

Artist's impression of brown dwarf ULAS J222711-004547, which has a very thick cloud layer of mineral dust. The dust is making the brown dwarf appear redder than its counterparts. A brown dwarf isn't massive enough to sustain hydrogen fusion. It's a failed star. (Credit: Neil J. Cook, Centre for Astrophysics Research, University of Hertfordshire)

NGC 457 (also known as Skiing Cluster, Owl Cluster, ET Cluster). Open star cluster in Cassiopeia, discovered by William Herschel in 1787. (Image credit: Henryk Kowalewski)

NGC 1818: A Young Globular Cluster. [Credit: Diedre Hunter (Lowell Obs.) et al., HST, NASA] There are no known young globular clusters in our Milky Way Galaxy because conditions are not right for more to form. In our neighboring LMC galaxy., there is a "young" globular cluster. Itformed only about 40 million years ago - just yesterday in astronomical time. Mona Evans, "Galaxy or Cluster?" www.bellaonline.c...