Location via proxy:   [ UP ]  
[Report a bug]   [Manage cookies]                
SlideShare a Scribd company logo

Planetary nebulae formation

•Download as PPTX, PDF•
•

Planetary nebulae form during the late stages of evolution for low-to-medium mass stars. As a star expands into a red giant, it ejects its outer layers through pulsations and stellar winds. The hot core ionizes the ejected gas, causing it to glow brightly. This energized shell of nebulous gas appears as a planetary nebula. Examples are the Helix Nebula and Ring Nebula. More massive stars may explode as supernovae, leaving behind neutron stars or black holes, depending on the star's original mass. The document discusses these stages of stellar evolution and death that give rise to different astronomical phenomena like planetary nebulae and neutron stars.

1 of 28

1

PLANETARY NEBULA FORMATION SARANYA V.S Department of Space Engineering and Rocketry

2

STELLAR EVOLUTION- MAIN STAGES  The Collapse of an Interstellar Cloud  Fragmentation into smaller clumps — Stars  Hydrogen Burning -Main Sequence  Helium Burning - Red Giant  Higher “nuclear” fuels (depending on mass)  Death, depending on mass:  Planetary Nebula — White Dwarf  Supernova — Neutron Star  Supernova — Black Hole

3

DARK NEBULA  Ninety-nine percent of the material in the Universe is hydrogen and helium. Some of that is locked up in stars but the vast portion floats in the spaces that lay between them. The distances between stellar bodies is huge, the density of this material is exceedingly thin. some of it is shepherded by gravity and exploding stars into enormous nebulous clouds,

4

COLLAPSE OF INTERSTELLAR CLOUD  Interstellar Medium Contains Clouds.  T~10-100°K, M~10’s-1000’s of Msun  If gravitational pull exceeds gas (and B) pressure, gas collapses.

5

PROTOSTARFORMATION

6

EVOLUTION OF STARS / GROSS FEATURES:  M < 0.08 Msun – Brown Dwarf (no nuclear burning)  0.08 Msun < M < 0.5 Msun – Central hydrogen burning. Formation of a degenerate core. No helium ignition –End as a He white dwarf  0.5 Msun < M < 2 Msun – Central Hydrogen burning, Helium flash, Helium burning - End as CO White dwarf.

7

 2 Msun < M < 8 Msun – Central Hydrogen burning, Helium ignites non degenerately _ End as CO White dwarf.  8 Msun < M < 20 Msun – Numerous burning stages after Helium burning. Type II Supernova - ends as Neutron Star.  20 Msun < M – As above, but ends as a Black Hole.  Note: High masses are inaccurately known due to large wind mass loss during evolution

8

HYDROGEN BURNING Brown dwarfs Sub brown dwarfs Red dwarfs Super giants

9

HELIUM BURNING  Low mass star becomes white dwarf after about 100 billion years  Mid size star • red giant branch star (inert He core) • asymptotic giant branch star (inert C core) formation of planetary nebulae and further becomes white or black dwarf.  Massive star undergo supernova explosion and transforms into neutron star or black hole

10

RED GIANT EXPANSION

11

Asymptotic Giant Branch Stars & Planetary Nebulae Once He is exhausted in core, core continues to contract, He & H burn in shells, envelope expands.  At some point, envelope becomes unstable, and starts to pulsates, each time shedding some material.  Envelope ejected at ~ 30 km/s, and core contracts and cools Envelope becomes planetary nebula Core becomes white dwarf

12

PLANETARY NEBULA  During the red giant phase, the outer layers of the star are expelled via pulsations and strong stellar winds.  The exposed hot, luminous core emits ultraviolet radiation that ionizes the ejected outer layers of the star.  This energized shell of nebulous gas reradiates the absorbed ultraviolet energy at visible frequencies and appears as a planetary nebula.

13

Planetary nebula formation

14

Ring nebula Lemon slice nebulaNecklace nebula Crab nebula

15

Eskimo nebula

16

Helix nebula

17

Formation of helix nebula

18

Cats eye nebula

19

Planetary nebulae formation

20

Bipolar nebulae

21

Formation of bipolar nebulae

22

ADVANCED BURNING IN MASSIVE STARS Shells:

23

SUPERNOVAE  One Iron photodisintegration takes place, core collapses on time scale of 10’s of ms.  At “Low” masses, Neutron star is formed, and shock appears.  As long as there is large fluxes of infalling material, shock cannot “leave” the core. Once shock does propagates outwards (perhaps using n heating) it:  Heats the envelope (fast nuclear processes take place (making Trans- Iron isotopes). Accelerates the envelope, and it is ejected with speeds of order 10,000’s km/s

24

 Cloud Gravitationally Unstable And Starts Collapsing. Flow Limited By Formation Of Shock Waves

25

LEFT OVERS OF MASSIVE STARS  The remnant left can be either a Neutron Star: Or a Black Hole!  Neutron stars are held by degeneracy pressure of neutrons (and not electrons) sun

26

Neutron star Black hole If the collapsing stellar core at the center of a supernova contains between about 1.4 and 3 solar masses, the collapse continues until electrons, protons neutrons are expelled, producing a neutron star If the collapsed stellar core is larger than three solar masses, it collapses completely to form a black hole: an infinitely dense object whose gravity is so strong that nothing can escape its immediate proximity, not even light

27

CONCLUSION Man’s inquisitiveness to know about the outer space has led to the discovery of several secrets of space. The formation, evolution and the death of the stars and nebulae is discussed in this seminar. This topic has become an interesting topic of research by the scientists all over the world and covers a vast area of astronomy. The outer space is limitless……. And hence the discussion goes on…

28

Thank you

More Related Content

Planetary nebulae formation

  • 1. PLANETARY NEBULA FORMATION SARANYA V.S Department of Space Engineering and Rocketry
  • 2. STELLAR EVOLUTION- MAIN STAGES  The Collapse of an Interstellar Cloud  Fragmentation into smaller clumps — Stars  Hydrogen Burning -Main Sequence  Helium Burning - Red Giant  Higher “nuclear” fuels (depending on mass)  Death, depending on mass:  Planetary Nebula — White Dwarf  Supernova — Neutron Star  Supernova — Black Hole
  • 3. DARK NEBULA  Ninety-nine percent of the material in the Universe is hydrogen and helium. Some of that is locked up in stars but the vast portion floats in the spaces that lay between them. The distances between stellar bodies is huge, the density of this material is exceedingly thin. some of it is shepherded by gravity and exploding stars into enormous nebulous clouds,
  • 4. COLLAPSE OF INTERSTELLAR CLOUD  Interstellar Medium Contains Clouds.  T~10-100°K, M~10’s-1000’s of Msun  If gravitational pull exceeds gas (and B) pressure, gas collapses.
  • 6. EVOLUTION OF STARS / GROSS FEATURES:  M < 0.08 Msun – Brown Dwarf (no nuclear burning)  0.08 Msun < M < 0.5 Msun – Central hydrogen burning. Formation of a degenerate core. No helium ignition –End as a He white dwarf  0.5 Msun < M < 2 Msun – Central Hydrogen burning, Helium flash, Helium burning - End as CO White dwarf.
  • 7.  2 Msun < M < 8 Msun – Central Hydrogen burning, Helium ignites non degenerately _ End as CO White dwarf.  8 Msun < M < 20 Msun – Numerous burning stages after Helium burning. Type II Supernova - ends as Neutron Star.  20 Msun < M – As above, but ends as a Black Hole.  Note: High masses are inaccurately known due to large wind mass loss during evolution
  • 8. HYDROGEN BURNING Brown dwarfs Sub brown dwarfs Red dwarfs Super giants
  • 9. HELIUM BURNING  Low mass star becomes white dwarf after about 100 billion years  Mid size star • red giant branch star (inert He core) • asymptotic giant branch star (inert C core) formation of planetary nebulae and further becomes white or black dwarf.  Massive star undergo supernova explosion and transforms into neutron star or black hole
  • 11. Asymptotic Giant Branch Stars & Planetary Nebulae Once He is exhausted in core, core continues to contract, He & H burn in shells, envelope expands.  At some point, envelope becomes unstable, and starts to pulsates, each time shedding some material.  Envelope ejected at ~ 30 km/s, and core contracts and cools Envelope becomes planetary nebula Core becomes white dwarf
  • 12. PLANETARY NEBULA  During the red giant phase, the outer layers of the star are expelled via pulsations and strong stellar winds.  The exposed hot, luminous core emits ultraviolet radiation that ionizes the ejected outer layers of the star.  This energized shell of nebulous gas reradiates the absorbed ultraviolet energy at visible frequencies and appears as a planetary nebula.
  • 14. Ring nebula Lemon slice nebulaNecklace nebula Crab nebula
  • 22. ADVANCED BURNING IN MASSIVE STARS Shells:
  • 23. SUPERNOVAE  One Iron photodisintegration takes place, core collapses on time scale of 10’s of ms.  At “Low” masses, Neutron star is formed, and shock appears.  As long as there is large fluxes of infalling material, shock cannot “leave” the core. Once shock does propagates outwards (perhaps using n heating) it:  Heats the envelope (fast nuclear processes take place (making Trans- Iron isotopes). Accelerates the envelope, and it is ejected with speeds of order 10,000’s km/s
  • 24.  Cloud Gravitationally Unstable And Starts Collapsing. Flow Limited By Formation Of Shock Waves
  • 25. LEFT OVERS OF MASSIVE STARS  The remnant left can be either a Neutron Star: Or a Black Hole!  Neutron stars are held by degeneracy pressure of neutrons (and not electrons) sun
  • 26. Neutron star Black hole If the collapsing stellar core at the center of a supernova contains between about 1.4 and 3 solar masses, the collapse continues until electrons, protons neutrons are expelled, producing a neutron star If the collapsed stellar core is larger than three solar masses, it collapses completely to form a black hole: an infinitely dense object whose gravity is so strong that nothing can escape its immediate proximity, not even light
  • 27. CONCLUSION Man’s inquisitiveness to know about the outer space has led to the discovery of several secrets of space. The formation, evolution and the death of the stars and nebulae is discussed in this seminar. This topic has become an interesting topic of research by the scientists all over the world and covers a vast area of astronomy. The outer space is limitless……. And hence the discussion goes on…