Transcript
Stars of the universeBINARY AND VARIABLE STARS.
GALAXY, NEBULAE AND STAR CLUSTERS
HUGE MASS OF STARS SMALLEST GALAXY -100000 STARS LARGEST GALAXY-3000 BILLION STARS MILKY WAY SPIRAL GALAXY GALAXY ROTATING IN SPACE,WITH STARS
MOVING FASTER.
GALAXY
CLOUD OF DUST AND GAS EMISSION AND REFLECTION NEBULAE NEBULAE OF DYING STARS : PLANETARY
NEBULAE AND SUPERNOVA REMNANTS OPEN AND GLOBULAR CLUSTERS
NEBULAE AND STARS CLUSTERS
BC HIPPARCHUS’ CLASSIFICATION 6 GROUP CATEGORISATION 1ST GROUP- BRIGHTEST STARS 6TH GROUP-FAINTEST STARS 1ST MAGNITUDE STAR= 100 X 6TH
MAGNITUDE
STELLAR MAGNITUDE SEQUENCE
POGSON’S CALIBERATION
Bm/Bn=(n-m)Log2.512
LUMINOSITIES OF STAR
L = 4πr2 σ T4eff
COLOUR INDEX OF STAR
HOT STARS COOL STARS
SHORTER WAVELENGTH
HIGH TEMPERATURES EMITS MORE LIGHT OF
BLUE VIOLET
LONGER WAVELENGTH LOW TEMPERATURES EMITS MORE LIGHT OF
YELLOW RED COLOUR
KNOWLEDGE PROGRESSED IN TWO STEPS 1. MASS DETERMINATION 2.RELATIONSHIP BETWEEN MASS AND
LUMINOSITIES.
BINARY STARS
KINDS OF BINARY
1.VISUAL BINARY2.SPECTROSCOPIC BINARY
3. ECLIPSING BINARY
1867, JOHN STONEY’S THEORY MACMILLAN’S THOERY FISSION THEORY
ORIGIN OF BINARY STARS
FORMATION OF ROCHE LOBES FILLING OF ROCHE LOBE
MASS TRANSFER IN CLOSE BINARY SYSTEMS
WIDE SEPARATION IN ORBITS REVOLUTION OF FAINTER STAR ABOUT ITS
BRIGHTER COMPONENT WITH A COMMON CENTER OF GRAVITY.
ANGULAR SEPARATION AND THE POSITION ANGLE.
VISUAL BINARIES
VISUAL BINARY
ACCRETION DISK
SIRIUS SEEN BY HUBBLE TELESCOPE
SIRIUS (49.5 YEARS) CYGNI (720 YEARS) ᾳ-CENTURI (80 YEARS)
EXAMPLES
PICKERING’S OBSERVATION SHIFTING OF ABSORPTION LINES CLOSE STARS OF EQUAL BRIGHTNESS. DOPPLER SHIFTS- VELOCITY CURVES MASS- AMPLITUDE OF VELOCITY CURVE
RELATIONSHIP1. 2πrp = vpƮ2. 2πrs = vsƮ also,3. mp/ms = rs/rp = vs/vp
SPECTROSCOPIC BINARY
FIRST OBSERVED IN MIZAR SHORTEST PEROD OF REVOLUTION 1. VISUAL-4.5YEARS 2. SPECTROSCOPIC- FEW HOURS TO 150
DAYS.
EXAMPLE
PERIOD ECLIPSE OCCURRENCE TOTAL AND ANNULAR ECLIPSES BASED ON
SIZE OF STARS. CHANGE IN LIGHT INTENSITY.
ECLIPSING BINARIES
EXAMPLE- ALGOL
LIGHT CURVE OF ECLIPSING BINARY
STARS ORBITTING ARPOUND EMPTY SPACE NO VISIBLE COMPANION DIM,MASKED BY GLARE OF PRIMARY, EMITS
LITTLE OR NO RADIATION
ASTROMETRIC BINARIES
CENTRE OF MASS CALCULATION IN BINARIES
MOTION OF STARS AROUND COMMON BARYCENTRE
EQUAL MASSES
SMALL DIFFERENCE IN MASS
LARGE DIFFERENCE IN MASS
EXTREME MASS DIFFERENCE
SIMILAR MASSES ORBITTING IN ELLIPSE AROUND COMMON B.C.
INTRINSIC VARIABLES EXTRINSIC VARIABLES LIGHT CURVES DATA
1. BRIGHTNESS VARIATIONS PERIODICAL,SEMIPERIODICAL, IRREGULAR
2. SHAPE OF LIGHT CURVES
VARIABLE STARS
PULSATING- ALTERNATE EXPANSION & CONTRACTION
ERUPTIVE- ERUPTIONS AND FLARES ON SURFACE
CATACLYSMIC OR EXPLOSIVE VARIABLES
INTRINSIC VARIABLES
EFFECECLIPSING BINARIES, DOUBLE STARS ROTATING VARIABLES – (SUNSPOT TS)
EXTRINSIC VARIABLES
HERTZSPRUNG –RUSSELL DIAGRAM FOR INTRINSIC VARIABLES
CEPHEIDS-CLASSICAL CEPHEIDS, TYPE II, RR LYRAE, DELTA SCUTI ETC.
LONG PERIOD VARIABLES- MIRA, SEMIREGULAR, SLOW IRREGULAR
SLOW PULSATING B STARS RV TAURI ALPHA CYGNI PULSATING WHITE DWARFS
EXAMPLES
INFORMATION OF MASS, RADIUS, TEMPERATURE AND LUMINOSITY
UNDERSTANDING NATURE OF DIFFERENT STARS SYSTEMATIC ANALYZING- PHOTOGRAPHIC,
PHOTOELECTRIC AND CALIBERATED COUPLED DEVICE (CCD)
CEPHEID VARIABLES HELPS IN DETERMINING AGE OF UNIVERSE
CATACLYSMIC HELPS IN UNDERSTANDING ACTIVE GALAXIES AND SUPERMASSIVE BLACK HOLES.
RESEARCH ON STARS
THERE WILL ALWAYS BE SOME MYSTERIES HIDDEN WITHIN THE STARS AND THE ETERNAL QUEST TO COMPREHEND THE SPLENDOUR OF HEAVENS WILL NEVER CEASE
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