This document discusses different types of nebulae in space. It begins by defining a nebula as an interstellar cloud of dust, gases, and plasma that appears cloud-like and glows due to hot gases. Nebulae form from collapsing clouds in the interstellar medium or from material ejected during supernova explosions. The document describes several categories of nebulae including emission nebulae that emit light, reflection nebulae that reflect light, dark nebulae that absorb light, planetary nebulae formed by old stars, and supernova remnants. Examples like the Orion Nebula, Eagle Nebula, and Crab Nebula are provided to illustrate different types of nebulae.

1. Nebulae
By: Ketan Agrawal
Photo by Credit: NASA, Jeff Hester, and Paul Scowen (Arizona State University) / Public domain

2. Contents
• What is a Nebula
• Formation
• Types of nebulae

3. What is a
Nebula
• A nebula is named after the Latin word for
“cloud”
• It is an interstellar cloud of dust, hydrogen,
helium and other ionized gases.
• These also contain astronomical plasma.
• It shines because the gas is very hot and it
has a lot of other elements in ionized state
that absorb and reemit radiation at
different wavelengths.
This Photo by Unknown Author is licensed under CC BY-SA

4. Formation
• A nebula forms in two ways:
• From interstellar medium.
• From Supernova.
Photo by NASA, Hui Yang University of Illinois ODNursery of New Stars /
Public domain

5. Formation
from
interstellar
medium
• the interstellar medium (ISM) is the matter and
radiation that exists in the space between the star
systems in a galaxy..
• Mutual gravitational attraction causes these matter
to clump together, forming regions of greater and
greater density.
• From this, stars may form in the center of the
collapsing material, who’s ultraviolet ionizing
radiation causes the surrounding gas to become
visible at optical wavelengths.
This Photo by Unknown Author is licensed under CC BY-SA

6. Formation from
Supernova
• When a giant star or white
dwarf star explodes in a
supernova the explosion hurls
the material into space that
matter can gather into a nebula.
This Photo by Unknown Author is licensed under CC BY-SA

7. Types of nebulae
• Nebulae can be classified as:
• Stellar Nurseries
• Emmision nebulae
• Reflection nebulae
• Dark nabulae
• Planetary nebulae
• Supernova remnants

8. Stellar nuseries
• these are star-forming regions also known as stellar
nurseries.
• In these huge areas of hydrogen gas gravity pulls the
materials together into large clumps which in turn attract
more material more and more gas squeezes together
harder and harder making it grow hotter and hotter. When
it becomes hot enough it will be a new star whatever is left
over may become planets circling them.

9. ORION NEBULA
• The Orion Nebula is a diffuse
nebula situated in the Milky Way,
being south of Orion's Belt in the
constellation of Orion. It is one of
the brightest nebulae, and is
visible to the naked eye in the
night sky. M42 is located at a
distance of 1,344 ± 20 light years
and is the closest region of
massive star formation to Earth.
The M42 nebula is estimated to be
24 light years across. It has a mass
of about 2000 times the mass of
the Sun
This Photo by Unknown Author is licensed under CC BY-SA

11. THE EAGLE NEBULA
• The Eagle Nebula is a young open cluster of stars in the
constellation Serpens, discovered by Jean-Philippe de
Chéseaux in 1745–46. Both the "Eagle" and the "Star Queen"
refer to visual impressions of the dark silhouette near the
center of the nebula, an area made famous as the "Pillars of
Creation" photographed by the Hubble Space Telescope.
This Photo by Unknown Author is licensed under CC BY-SA

12. This Photo by Unknown Author is licensed under CC BY-SA
The Pillars of Creation

13. DWARF GALAXY ESO 553-46 HAS ONE OF THE HIGHEST RATES OF STAR
FORMATION OF THE 1000 OR SO GALAXIES NEAREST TO THE MILKY WAY.

14. STAR FORMATION IN THE 30 DORADUS NEBULA

15. Emission nebula
• An emission nebula is a nebula formed of ionized gases
that emit light of various colors. The most common
source of ionization is high-energy photons emitted
from a nearby hot star.
This Photo by Unknown Author is licensed under CC BY-SA

16. Emission nebula LHA 120-
N55

17. emission nebula
NGC 2174

18. Reflection
Nebulae
• Reflection nebulae are clouds of dust which are
simply reflecting the light of a nearby star or stars.
Reflection nebulae are also usually sites of star
formation. They are usually blue because the
scattering is more efficient for blue light. Reflection
nebulae and emission nebulae are often seen
together and are sometimes both referred to as
diffuse nebulae.
This Photo by Unknown Author is licensed under CC BY-SA

19. The Witch Head reflection nebula
(IC2118), about 900 light years from
earth, is associated with the bright
star Rigel in the constellation Orion

20. Reflection nebula IC 2631

21. Dark Nebulae
• Dark nebulae are clouds of dust which are
simply blocking the light from whatever is
behind. They are physically very similar to
reflection nebulae; they look different only
because of the geometry of the light
source, the cloud and the Earth.
• Dark nebulae are also often seen in
conjunction with reflection and emission
nebulae.
This Photo by Unknown Author is licensed under CC BY-NC

22. Horsehead Nebula:
The Horsehead Nebula is a dark
nebula in the constellation Orion.
The nebula is located just to the
south of the star Alnitak

23. Cone Nebula:
The Cone Nebula is an H II region in the constellation of
Monoceros. The nebula is located about 830 parsecs or
2,700 light-years away from Earth. The Cone Nebula
forms part of the nebulosity surrounding the Christmas
Tree Cluster.

24. Planetary
Nebulae
• Planetary nebulae are shells of gas thrown out by
some stars near the end of their lives.
• They consist of an expanding, glowing shell of
ionized gas ejected from old red giant stars late in
their lives.
• They have nothing at all to do with planets; the
terminology was invented because they often look
a little like planets in small telescopes.
• Our Sun will probably produce a planetary nebula
in about 5 billion years.
This Photo by Unknown Author is licensed under CC BY-NC

25. The Butterfly Nebula
This Photo by Unknown Author is licensed under CC BY-NC

26. This Photo by Unknown Author is licensed under CC BY-SA
• THE RING NEBULA

27. THE HELIX
NEBULA

28. Supernova
remnants
• A supernova remnant (SNR) is the
structure resulting from the explosion of a
star in a supernova.
• The supernova remnant is bounded by an
expanding shock wave, and consists of
ejected material expanding from the
explosion, and the interstellar material it
sweeps up and shocks along the way.

29. The Crab Nebula

30. The LMC N49

31. THANK YOU