Some of the most beautiful extended objects that we can see are HII regions, or diffuse or emission nebulae. So-named because they contain mostly ionized hydrogen (H+ or HII), HII regions are found throughout the interstellar medium in the Galaxy and in other galaxies. How are HII regions observed?
H II regions are found only in spiral galaxies like the Milky Way and irregular galaxies. They are not seen in elliptical galaxies. In irregular galaxies, they may be dispersed throughout the galaxy, but in spirals they are most abundant within the spiral arms.
Which is the same as an H II region?
H II region, also called diffuse nebula or emission nebula, interstellar matter consisting of ionized hydrogen atoms. How are emission nebulae formed?
An emission nebula is a nebula formed of ionized gases that emit light of various wavelengths. The most common source of ionization is high-energy ultraviolet photons emitted from a nearby hot star.
What is the space between stars called?
The space between stars is known as interstellar space, and so the space between galaxies is called intergalactic space. What is the protostar stage?
A protostar is a very young star that is still gathering mass from its parent molecular cloud. The protostellar phase is the earliest one in the process of stellar evolution. For a low-mass star (i.e. that of the Sun or lower), it lasts about 500,000 years.
Frequently Asked Questions(FAQ)
What gases are in a nebula?
How do stars form in a nebula? Nebulae are made of dust and gases—mostly hydrogen and helium. The dust and gases in a nebula are very spread out, but gravity can slowly begin to pull together clumps of dust and gas.
What causes dark nebula?
What causes a dark nebula? They are caused by interstellar clouds with a very high concentration of dust grains obscuring light. These dust clouds obscure and block visible light objects behind it. Such as background stars or emission or reflection nebulae.
What is an HII region in the Milky Way?
HII regions are emission nebulae created when young, massive stars ionise nearby gas clouds with high-energy UV radiation. They are composed primarily of hydrogen, hence the name (astronomers use the term HII to refer to ionised hydrogen, HI for neutral hydrogen), and have temperatures of around 10,000 Kelvin.
What is the medium of space?
The interstellar medium is composed, primarily, of hydrogen, followed by helium with trace amounts of carbon, oxygen, and nitrogen comparatively to hydrogen. … Table 1: Components of the interstellar medium.
| Scale height (pc) | 1000 |
|---|---|
| Temperature (K) | 8000 |
| Density (particles/cm3) | 0.2–0.5 |
| State of hydrogen | ionized |
What is ionized hydrogen?
What is HI and HII hydrogen?
Such regions of ionized hydrogen are called HII regions, while cold un-ionized hydrogen clouds are termed HI regions (with the I and II referring to the ionization state of the hydrogen). … It takes 13.6 electon-Volts of energy to ionize a hydrogen atom, which implies a wavelength of 91.2 nm.
What are Astrophysical differences between planetary nebulae and HII regions?
Planetary nebulae are considerably denser than most H II regions, typically containing 1,000–10,000 atoms per cubic cm within their dense regions, and have a surface brightness 1,000 times larger.
Why do HII regions appear red quizlet?
Why do HII regions appear red? HII regions are composed of completely ionized hydrogen. When the hydrogen captures an electron, light is emitted. The red Balmer hydrogen line is the strongest wavelength emitted.
Why nebula is red?
Emission nebulae tend to be red in color because of the abundance of hydrogen. Additional colors, such as blue and green, can be produced by the atoms of other elements, but hydrogen is almost always the most abundant.
Can you breathe in a nebula?
Could a star exist with this cloud similar to earth atmosphere around it where a person could breathe without much effort? Nope. The solar wind and radiation pressure and a combination of planetary and stellar gravity would either blow away or hoover up all the gas cloud in relatively short order.
What’s a remnant of a supernova?
A supernova remnant (SNR) is the remains of a supernova explosion. SNRs are extremely important for understanding our galaxy. They heat up the interstellar medium, distribute heavy elements throughout the galaxy, and accelerate cosmic rays.
What are interstellar gasses?
The gas between stars is mostly hydrogen and helium scattered at varying densities between the stars in our galaxy and other galaxies. The proportions of the gases are similar to those in the Sun. Interstellar gas supplies the raw material for star formation.
How many galaxies are there?
All in all, Hubble reveals an estimated 100 billion galaxies in the universe or so, but this number is likely to increase to about 200 billion as telescope technology in space improves, Livio told Space.com.
What is outside the universe?
The universe, being all there is, is infinitely big and has no edge, so there’s no outside to even talk about. … The current width of the observable universe is about 90 billion light-years. And presumably, beyond that boundary, there’s a bunch of other random stars and galaxies.
What are the 7 parts of the Stars?
Seven Main Stages of a Star
- Giant Gas Cloud. A star originates from a large cloud of gas. …
- Protostar. When the gas particles in the molecular cloud run into each other, heat energy is produced. …
- T-Tauri Phase. …
- Main Sequence. …
- Red Giant. …
- The Fusion of Heavier Elements. …
- Supernovae and Planetary Nebulae.
What are the 4 stages of a star?
The formation and life cycle of stars
- A nebula. A star forms from massive clouds of dust and gas in space, also known as a nebula. …
- Protostar. As the mass falls together it gets hot. …
- Main sequence star. …
- Red giant star. …
- White dwarf. …
- Supernova. …
- Neutron star or black hole.
Why is a protostar important?
A protostar becomes a main sequence star when its core temperature exceeds 10 million K. This is the temperature needed for hydrogen fusion to operate efficiently. The length of time all of this takes depends on the mass of the star. The more massive the star, the faster everything happens.
Where are stars born?
nebulas Like people, stars are born, they grow old and they die. Their birth places are huge, cold clouds of gas and dust, known as ‘nebulas’. The most famous of these is the Orion nebula, which is just visible with the unaided eye. These clouds start to shrink under their own gravity.
Is Earth in a nebula?
The Earth was formed from the nebula that produced the Solar System. It is almost universally accepted that the Sun, the planets and their satellites, the asteroids, and the comets of the Oort ‘cloud’ grew from a cloud of gas and dust that contracted under its own gravity.
Is nebula bigger than galaxy?
Simply put, the main difference between galaxies and nebulae are an extreme difference in size, as well as their basic structure. A nebula is a cloud of dust and gas, usually tens to hundreds of light years across. A galaxy is much larger — usually thousands to hundreds of thousands of light years across.
Graduated from ENSAT (national agronomic school of Toulouse) in plant sciences in 2018, I pursued a CIFRE doctorate under contract with Sun’Agri and INRAE in Avignon between 2019 and 2022. My thesis aimed to study dynamic agrivoltaic systems, in my case in arboriculture. I love to write and share science related Stuff Here on my Website. I am currently continuing at Sun’Agri as an R&D engineer.