Astronomical spectroscopy

spectrumspectroscopicspectrastellar spectraspectroscopystellar spectrumstellar spectroscopyspectralastronomyradio spectroscopy
Astronomical spectroscopy is the study of astronomy using the techniques of spectroscopy to measure the spectrum of electromagnetic radiation, including visible light and radio, which radiates from stars and other celestial objects.wikipedia
704 Related Articles

Spectroscopy

spectroscopiclaser spectroscopyspectroscopist
Astronomical spectroscopy is the study of astronomy using the techniques of spectroscopy to measure the spectrum of electromagnetic radiation, including visible light and radio, which radiates from stars and other celestial objects.
Spectroscopy is also used in astronomy and remote sensing on Earth.

Charles Augustus Young

Charles A. YoungC. A. YoungCharles Young
In 1869 the astronomers Charles Augustus Young and William Harkness independently observed a novel green emission line in the Sun's corona during an eclipse. This "new" element was incorrectly named coronium, as it was only found in the corona. It was not until the 1930s that Walter Grotrian and Bengt Edlén discovered that the spectral line at 530.3 nm was due to highly ionized iron (Fe 13+ ). Other unusual lines in the coronal spectrum are also caused by highly charged ions, such as nickel and calcium, the high ionization being due to the extreme temperature of the solar corona.
Charles Augustus Young (December 15, 1834 – January 4, 1908) one of the foremost solar spectroscopist astronomers in the United States, died of pneumonia after a brief illness, at his home in Hanover, New Hampshire, on 4 January 1908.

Spectrophotometry

spectrophotometerspectrophotometricspectrophotometers
The flux scale of a spectrum can be calibrated as a function of wavelength by comparison with an observation of a standard star with corrections for atmospheric absorption of light; this is known as spectrophotometry.
In astronomy, the term spectrophotometry refers to the measurement of the spectrum of a celestial object in which the flux scale of the spectrum is calibrated as a function of wavelength, usually by comparison with an observation of a spectrophotometric standard star, and corrected for the absorption of light by the Earth's atmosphere.

Sun

solarSolThe Sun
To date more than 20 000 absorption lines have been listed for the Sun between 293.5 and 877.0 nm, yet only approximately 75% of these lines have been linked to elemental absorption.
The solar heavy-element abundances described above are typically measured both using spectroscopy of the Sun's photosphere and by measuring abundances in meteorites that have never been heated to melting temperatures.

Betelgeuse

α OriBetelg'''euseBetelgeuse mass loss
Soon after this, he combined telescope and prism to observe the spectrum of Venus, the Moon, Mars, and various stars such as Betelgeuse; his company continued to manufacture and sell high-quality refracting telescopes based on his original designs until its closure in 1884.
Lines in the spectrum of Betelgeuse show doppler shifts indicating radial velocity changes corresponding, very roughly, to the brightness changes.

Stellar classification

spectral typeK-typeG-type
This composite spectrum becomes easier to detect when the stars are of similar luminosity and of different spectral class.
In astronomy, stellar classification is the classification of stars based on their spectral characteristics.

Absorption spectroscopy

absorption spectrumabsorption spectraabsorption
By comparing the absorption lines of the sun with emission spectra of known gases, the chemical composition of stars can be determined.
Astronomical spectroscopy is a particularly significant type of remote spectral sensing.

Photographic plate

photographic platesglass plateglass plates
Historically, photographic plates were widely used to record spectra until electronic detectors were developed, and today optical spectrographs most often employ charge-coupled devices (CCDs).
Several important applications of astrophotography, including astronomical spectroscopy and astrometry, continued using plates until digital imaging improved to the point where it could outmatch photographic results.

Redshift

red shiftzred-shift
Because of the Doppler effect, objects moving towards us are blueshifted, and objects moving away are redshifted.
Redshifts are also seen in the spectroscopic observations of astronomical objects.

Venus

Morning Starevening starCytherocentric
Soon after this, he combined telescope and prism to observe the spectrum of Venus, the Moon, Mars, and various stars such as Betelgeuse; his company continued to manufacture and sell high-quality refracting telescopes based on his original designs until its closure in 1884.
Its almost featureless disc gave no hint what its surface might be like, and it was only with the development of spectroscopic, radar and ultraviolet observations that more of its secrets were revealed.

Joseph von Fraunhofer

FraunhoferJoseph FraunhoferFraunhofer refracting telescope
In the early 1800s Joseph von Fraunhofer used his skills as a glass maker to create very pure prisms, which allowed him to observe 574 dark lines in a seemingly continuous spectrum.
He found that the spectra of Sirius and other first-magnitude stars differed from the sun and from each other, thus founding stellar spectroscopy.

Emission spectrum

emissionemission spectraemission spectroscopy
By comparing the absorption lines of the sun with emission spectra of known gases, the chemical composition of stars can be determined.
One example is astronomical spectroscopy: identifying the composition of stars by analysing the received light.

Dark matter

dark matter detectiondark-mattermissing mass
Zwicky hypothesized that there must be a great deal of non-luminous matter in the galaxy clusters, which became known as dark matter.
In astronomical spectroscopy, the Lyman-alpha forest is the sum of the absorption lines arising from the Lyman-alpha transition of neutral hydrogen in the spectra of distant galaxies and quasars.

White dwarf

white dwarfswhite dwarf starcentral star
The chemical reactions that form these molecules can happen in cold, diffuse clouds or in the hot ejecta around a white dwarf star from a nova or supernova.
Since hotter bodies radiate more energy than colder ones, a star's surface brightness can be estimated from its effective surface temperature, and that from its spectrum.

Fraunhofer lines

calcium K linecalcium K-lineFraunhofer
The major Fraunhofer lines, and the elements with which they are associated, appear in the following table.
The Fraunhofer H and K letters are also still used for the calcium-II doublet in the violet part of the spectrum, important in astronomical spectroscopy.

Coronium

In 1869 the astronomers Charles Augustus Young and William Harkness independently observed a novel green emission line in the Sun's corona during an eclipse. This "new" element was incorrectly named coronium, as it was only found in the corona. It was not until the 1930s that Walter Grotrian and Bengt Edlén discovered that the spectral line at 530.3 nm was due to highly ionized iron (Fe 13+ ). Other unusual lines in the coronal spectrum are also caused by highly charged ions, such as nickel and calcium, the high ionization being due to the extreme temperature of the solar corona.
During the total solar eclipse of 7 August 1869, a green emission line of wavelength 530.3 nm was independently observed by Charles Augustus Young (1834–1908) and William Harkness (1837–1903) in the coronal spectrum.

Spectrometer

spectrometersspectrometryspectrograph
For cooler objects, including solar-system planets and asteroids, most of the emission is at infrared wavelengths we cannot see, but that are routinely measured with spectrometers.
Spectrometers are used in astronomy to analyze the chemical composition of stars and planets, and spectrometers gather data on the origin of the universe.

Supernova

supernovaecore-collapse supernovasupernovas
The chemical reactions that form these molecules can happen in cold, diffuse clouds or in the hot ejecta around a white dwarf star from a nova or supernova.
As part of the attempt to understand supernovae, astronomers have classified them according to their light curves and the absorption lines of different chemical elements that appear in their spectra.

Visible spectrum

visiblevisible lightspectrum
Astronomical spectroscopy is used to measure three major bands of radiation: visible spectrum, radio, and X-ray.
Typically, astronomical spectroscopy uses high-dispersion diffraction gratings to observe spectra at very high spectral resolutions.

Nebulium

ionised oxygen emission
However, there were several emission lines that could not be linked to any terrestrial element, brightest among them lines at 495.9 nm and 500.7 nm. These lines were attributed to a new element, nebulium, until Ira Bowen determined in 1927 that the emission lines were from highly ionised oxygen (O +2 ).
Many of these, such as the Andromeda Nebula, had spectra that looked like stellar spectra, and these turned out to be galaxies.

Continuous spectrum

continuumcontinuous spectraContinuous
Hot solid objects produce light with a continuous spectrum, hot gases emit light at specific wavelengths, and hot solid objects surrounded by cooler gases show a near-continuous spectrum with dark lines corresponding to the emission lines of the gases.
Astronomical spectroscopy (examples of continuous spectra)

Cosmic distance ladder

standard candlestandard candlesdistance
Bright stars in galaxies can also help determine the distance to a galaxy, which may be a more accurate method than parallax or standard candles.
Many stars have features in their spectra, such as the calcium K-line, that indicate their absolute magnitude.

Balmer series

BalmerseriesBalmer lines
Designations from the early Balmer Series are shown in parentheses.
Astronomical spectroscopy

William Huggins

Sir William HugginsHugginsHuggins, Sir William
In 1864 William Huggins noticed that many nebulae showed only emission lines rather than a full spectrum like stars.

Lyman-alpha forest

Lyman alpha absorption forestLyman-α forestultraviolet spectrometer
In astronomical spectroscopy, the Lyman-alpha forest is a series of absorption lines in the spectra of distant galaxies and quasars arising from the Lyman-alpha electron transition of the neutral hydrogen atom.