Presentation on theme: "E treme Stars Caty Pilachowski Mini-University June 2012."— Presentation transcript:
1 E treme StarsCaty PilachowskiMini-UniversityJune 2012
2 Brightest Star in the night sky SIRIUSAlpha Canis MajorisThe Dog StarSirius b –faint companion
3 Most Distant Star (that you can see!) DenebDeneb = Alpha CygniDistance: ~ 1500 LYDiameter: ~20 x SunMass: ~20 x SunLuminosity: 60,000 x Sun1 LY =9,460,528,400,000 Km
4 The Closest Star Our Sun is a typical, middle-aged star Age: Distance: 150 million KmThe Closest StarDiameter:1.4 million Km= 100 x EarthOur Sun is a typical, middle-aged starTemperature:6,000 C (outside)15 million C (inside)Mass:2 x 1030 kg= 300,000 x EarthAge:4.6 billion years
5 A Range of Size and Mass 0.08 MSun ~200 MSun 0.1 MSun ~1000 MSun DIAMETER0.1 MSun~1000 MSunOnly certain combinations of size and mass are stableStars will shrink or expand to reach stability
6 Cool stars are reddish in color A Range of TemperatureTEMPERATURE200,000 C2000 CThe Sun is about 6000 CHot stars are bluishin colorCool stars are reddish in colorA star’s brightness depends on its temperature and radius
8 The Sun formed 4.6 billion years ago A Range of AgesAGE~13 Billion YearsBrand New StarsThe Sun formed 4.6 billion years agoStars have been forming continuously since the Universe began 13.7 billion years agoSome old stars are still around; other stars are brand new
15 Future Sun The Sun as a red giant The Sun today The orbit of Venus Astronomers aren’t sure how big the Sun will grow when it becomes a red giant, Perhaps as large as the orbit of Venus, or even the orbit of the EarthThe Sun todayThe Sun as a red giantThe orbit of Venus
17 What’s Left? A White Dwarf Mass: 50% SunDensity: 1-2 tons per cc3Composition: C & O, the “ashes” of nuclear fusionCools & fades slowly12,000 KmSirius B
18 Sirius b Nearest White Dwarf Star Diameter: 1/100 Sun Mass: 98% Sun Distance: 8.6 LYSirius b
19 BIGGEST VY Canis Majoris The The Sun A red “hypergiant” star Credit: NASA/ESA/R Humphreys/U Minnesota)A red “hypergiant” starDiameter: 2000 x SunMass: x SunLuminosity: 500,000 x Sun5,000 light-years awayVY Canis Majoris
20 BRIGHTEST & MOST MASSIVE Mass = 265 Suns (probably 320 Suns at birth!)Luminosity = 8-9 million x SunDiameter: 35 x SunDistance: 165,000 LYFuture hypernova?R136A*Located in the Large Magellanic Cloud
21 The HOTTEST STARS are tiny, dim, new white dwarfs T=200,000 C NGC 2440 (central star)Distance: 4500 LYNGC 6302 (central star)Distance: 3800 LYHidden by central dust ringKPDDistance: 2500 LYOnly 2200 years “old”
22 COLDEST Stars The Brown Dwarfs! WISE 1828+2650 Temperature ~25 C About 27 LYMass < 0.1 SunsToo small for nuclear fusion
23 The Oldest Stars! HE 1523-0901 13.2 billion years old Mass: 0.8 Suns Distance: ~7500 LYA red giant starToday13.2 billionYears ago
24 The Youngest StarsStars are forming today in the “empty” regions of interstellar space.
27 The Famous Pleiades Distance: 1300 LY Brightest Star Cluster Formed about 115 million years agoThe blue glow is dust!
28 V838 Monocerotis – The Light Echo V838 is a “central star” of a planetary nebulaDistance: 20,000 LYMass: 5-10 Suns (originally much more massive)Outburst in The “expanding shell” is actually an expanding light echo
29 V838 Monocerotis – The Light Echo To EarthArrives firstArrives later
30 A Real Shooting Star! 13 LY tail 291,000 mph Mira = Omicron Ceti An unstable red giantLosing massDistance: 400 LYMass: 1.2 Suns13 LY tail291,000 mphGALEXGALEXAs seen by Hubble
31 Epsilon Aurigae Dust Disk Binary star (6 + 8 Suns) 27 year period One star is invisible!An unseen blue star hides in a disk of dust that orbits a yellow supergiantWhen the blue star passes in front of the yellow star, the disk blocks the light of yellow star8 AUDust Disk
32 Stellar CannibalismBinary stars that orbit close together often transfer mass between the starsSemi -Detached BinaryDetached BinaryContact BinaryWarning: Artist’s Conceptions
33 R Corona Borealis – The “Fade Out” Star Yellow supergiant starDistance: 6000 LYMass: 0.8 SunsSometimes fades by a factor of 1000 or more in brightness!Emits “puffs” of soot that block the light of the starThis star smokes!
34 More R Corona Borealis Extreme helium star Very little hydrogenLots of carbonOrigin: merger of two white dwarfs?
35 Extreme Spots! Artist Conception HD holds the record for the largest “starspot”Warning: Artist’s ConceptionThe rotation and revolution of close binary stars are locked together, forcing the stars to rotate as fast as they orbit. Fast rotation makes big spots.
37 Crab Pulsar MORE EXTREME ROTATION Distance: 6500 LY Mass: ~ SunsRemnant of 1054 SupernovaDensity: 100,000,000 tonsper thimblefulSpins 30 times per second
38 Magnetars! Extreme Neutron Stars SGRMagnetars! Extreme Neutron StarsSGRDistance: 20,000 LYMass: ~ 2 SunsDiameter: ~20 Km7 LYMost intense magnetic fields in the UniverseHundreds of millions times stronger than the strongest human-made magnetsOnly 5 knownSources of intense gamma ray burstsWarning: Artist’s Conception