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H-alpha (Hα) is a specific deep-red visible spectral line in the Balmer series created by hydrogen with a wavelength of 656.28 nm, which occurs when a hydrogen electron falls from its third to second lowest energy level. [1]

36 relations: Acetonitrile, Ammonia, Angstrom, Astronomy, Astrophotography, Atom, Atomic nucleus, Balmer series, Bandwidth (signal processing), Bohr model, Carbon dioxide, Carbon monoxide, Dichroic filter, Doppler effect, Electromagnetic spectrum, Electron, Emission nebula, Fabry–Pérot interferometer, Formaldehyde, Hydrogen, Hydrogen spectral series, Interference (wave propagation), Light pollution, Lyman series, Lyot filter, Nanometre, Nebula, Optical filter, Photon, Principal quantum number, Quantum, Rydberg formula, Solar prominence, Spectral line, Spectrohelioscope, Wavelength.


Acetonitrile is the chemical compound with the formula.

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Ammonia or azane is a compound of nitrogen and hydrogen with the formula NH3.

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The ångström or angstrom is a unit of length equal to (one ten-billionth of a metre) or.

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Astronomy is a natural science which is the study of celestial objects (such as stars, galaxies, planets, moons, asteroids, comets and nebulae), the physics, chemistry, and evolution of such objects, and phenomena that originate outside the atmosphere of Earth, including supernovae explosions, gamma ray bursts, and cosmic microwave background radiation.

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Astrophotography is a specialized type of photography for recording images of astronomical objects and large areas of the night sky.

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An atom is the smallest constituent unit of ordinary matter that has the properties of a chemical element.

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Atomic nucleus

The nucleus is the small, dense region consisting of protons and neutrons at the center of an atom.

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Balmer series

The Balmer series or Balmer lines in atomic physics, is the designation of one of a set of six named series describing the spectral line emissions of the hydrogen atom.

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Bandwidth (signal processing)

Bandwidth is the difference between the upper and lower frequencies in a continuous set of frequencies.

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Bohr model

In atomic physics, the Rutherford–Bohr model or Bohr model, introduced by Niels Bohr in 1913, depicts the atom as a small, positively charged nucleus surrounded by electrons that travel in circular orbits around the nucleus—similar in structure to the solar system, but with attraction provided by electrostatic forces rather than gravity.

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Carbon dioxide

Carbon dioxide (chemical formula CO2) is a colorless, odorless gas vital to life on Earth.

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Carbon monoxide

Carbon monoxide (CO) is a colorless, odorless, and tasteless gas that is slightly less dense than air.

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Dichroic filter

A dichroic filter, thin-film filter, or interference filter is a very accurate color filter used to selectively pass light of a small range of colors while reflecting other colors.

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Doppler effect

The Doppler effect (or Doppler shift) is the change in frequency of a wave (or other periodic event) for an observer moving relative to its source.

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Electromagnetic spectrum

The electromagnetic spectrum is the range of all possible frequencies of electromagnetic radiation.

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The electron is a subatomic particle, symbol or, with a negative elementary electric charge.

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Emission nebula

An emission nebula is a nebula formed of ionized gases that emit light of various colors.

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Fabry–Pérot interferometer

In optics, a Fabry–Pérot interferometer or etalon is typically made of a transparent plate with two reflecting surfaces, or two parallel highly reflecting mirrors.

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Formaldehyde is a naturally-occurring organic compound with the formula CH2O.

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

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Hydrogen spectral series

The emission spectrum of atomic hydrogen is divided into a number of spectral series, with wavelengths given by the Rydberg formula.

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Interference (wave propagation)

In physics, interference is a phenomenon in which two waves superpose to form a resultant wave of greater or lower amplitude.

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Light pollution

Light pollution, also known as photopollution or luminous pollution, is excessive, misdirected, or obtrusive artificial light.

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Lyman series

In physics and chemistry, the Lyman series is a hydrogen spectral series of transitions and resulting ultraviolet emission lines of the hydrogen atom as an electron goes from n ≥ 2 to n.

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Lyot filter

A Lyot filter, named for its inventor Bernard Lyot, is a type of optical filter that uses birefringence to produce a narrow passband of transmitted wavelengths.

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The nanometre (International spelling as used by the International Bureau of Weights and Measures; SI symbol: nm) or nanometer (American spelling) is a unit of length in the metric system, equal to one billionth of a metre (m).

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A nebula (Latin for "cloud"; pl. nebulae, nebulæ, or nebulas) is an interstellar cloud of dust, hydrogen, helium and other ionized gases.

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Optical filter

Optical filters are devices that selectively transmit light of different wavelengths, usually implemented as plane glass or plastic devices in the optical path which are either dyed in the bulk or have interference coatings.

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No description.

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Principal quantum number

The principal quantum number, symbolized as n, is the first of a set of quantum numbers (which includes the principal quantum number, the azimuthal quantum number, the magnetic quantum number, and the spin quantum number) of an atomic orbital.

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In physics, a quantum (plural: quanta) is the minimum amount of any physical entity involved in an interaction.

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Rydberg formula

The Rydberg formula is used in atomic physics to describe the wavelengths of spectral lines of many chemical elements.

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Solar prominence

A prominence is a large, bright, gaseous feature extending outward from the Sun's surface, often in a loop shape.

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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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A spectrohelioscope is a type of solar telescope designed by George Ellery Hale in 1924 to allow the Sun to be viewed in a selected wavelength of light.

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In physics, the wavelength of a sinusoidal wave is the spatial period of the wave—the distance over which the wave's shape repeats, and the inverse of the spatial frequency.

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[1] https://en.wikipedia.org/wiki/H-alpha

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