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H I region

Index H I region

An HI region or H I region (read H one) is a cloud in the interstellar medium composed of neutral atomic hydrogen (HI), in addition to the local abundance of helium and other elements. [1]

25 relations: Astronomer, Astronomy, Electronvolt, Extreme ultraviolet, Gravitational field, H II region, Helium, Hydrogen, Hydrogen line, Interacting galaxy, Interstellar cloud, Interstellar medium, Ionization, Isothermal process, Light, Lockman Hole, Metallicity, Milky Way, Photon, Radio telescope, Spectral line, Spiral galaxy, Temperature, Thermal equilibrium, X-ray.

Astronomer

An astronomer is a scientist in the field of astronomy who concentrates their studies on a specific question or field outside the scope of Earth.

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Astronomy

Astronomy (from ἀστρονομία) is a natural science that studies celestial objects and phenomena.

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Electronvolt

In physics, the electronvolt (symbol eV, also written electron-volt and electron volt) is a unit of energy equal to approximately joules (symbol J).

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Extreme ultraviolet

Extreme ultraviolet radiation (EUV or XUV) or high-energy ultraviolet radiation is electromagnetic radiation in the part of the electromagnetic spectrum spanning wavelengths from 124 nm down to 10 nm, and therefore (by the Planck–Einstein equation) having photons with energies from 10 eV up to 124 eV (corresponding to 124 nm to 10 nm respectively).

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Gravitational field

In physics, a gravitational field is a model used to explain the influence that a massive body extends into the space around itself, producing a force on another massive body.

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H II region

An H II region or HII region is a region of interstellar atomic hydrogen that is ionized.

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Helium

Helium (from lit) is a chemical element with symbol He and atomic number 2.

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Hydrogen

Hydrogen is a chemical element with symbol H and atomic number 1.

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Hydrogen line

The hydrogen line, 21-centimeter line or H I line refers to the electromagnetic radiation spectral line that is created by a change in the energy state of neutral hydrogen atoms.

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Interacting galaxy

Interacting galaxies (colliding galaxies) are galaxies whose gravitational fields result in a disturbance of one another.

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Interstellar cloud

An interstellar cloud is generally an accumulation of gas, plasma, and dust in our and other galaxies.

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Interstellar medium

In astronomy, the interstellar medium (ISM) is the matter and radiation that exists in the space between the star systems in a galaxy.

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Ionization

Ionization or ionisation, is the process by which an atom or a molecule acquires a negative or positive charge by gaining or losing electrons to form ions, often in conjunction with other chemical changes.

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Isothermal process

An isothermal process is a change of a system, in which the temperature remains constant: ΔT.

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Light

Light is electromagnetic radiation within a certain portion of the electromagnetic spectrum.

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Lockman Hole

The Lockman Hole is an area of the sky in which minimal amounts of neutral hydrogen gas are observed.

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Metallicity

In astronomy, metallicity is used to describe the abundance of elements present in an object that are heavier than hydrogen or helium.

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Milky Way

The Milky Way is the galaxy that contains our Solar System.

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Photon

The photon is a type of elementary particle, the quantum of the electromagnetic field including electromagnetic radiation such as light, and the force carrier for the electromagnetic force (even when static via virtual particles).

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Radio telescope

A radio telescope is a specialized antenna and radio receiver used to receive radio waves from astronomical radio sources in the sky in radio astronomy.

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Spectral line

A spectral line is a dark or bright line in an otherwise uniform and continuous spectrum, resulting from emission or absorption of light in a narrow frequency range, compared with the nearby frequencies.

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Spiral galaxy

Spiral galaxies form a class of galaxy originally described by Edwin Hubble in his 1936 work The Realm of the Nebulae(pp. 124–151) and, as such, form part of the Hubble sequence.

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Temperature

Temperature is a physical quantity expressing hot and cold.

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Thermal equilibrium

Two physical systems are in thermal equilibrium if there are no net flow of thermal energy between them when they are connected by a path permeable to heat.

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X-ray

X-rays make up X-radiation, a form of electromagnetic radiation.

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Redirects here:

H I, H I profile, H. I. Region, HI Region, HI region, Hydrogen cloud.

References

[1] https://en.wikipedia.org/wiki/H_I_region

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