QuasarActive galactic nucleus (AGN) containing a supermassive black holeArtist's image of the accretion disc in ULAS J1120+0641, a very distant quasar containing a supermassive black hole with a mass two billion times that of the SunThe Chandra X-ray image of PKS 1127-145, a quasar about 10 billion light-years from Earth. An X-ray jet extends at least a million light-years from the quasar. Image is 60 arcseconds on a side. RA 11h 30m 7.10s Dec −14° 49' 27" in Crater.
SpectroscopyStudy involving matter and electromagnetic radiationA prism separates white light by dispersing it into its component colors, which can then be studied using spectroscopy.Spectroscopy is the field of study that measures and interprets electromagnetic spectra as it interacts with matter. In narrower contexts, spectroscopy is the precise study of color as generalized from radiated visible light to all bands of the electromagnetic spectrum.
RedshiftChange in wavelength of lightAbsorption lines in the visible spectrum of a supercluster of distant galaxies (right), as compared to absorption lines in the visible spectrum of the Sun (left). Arrows indicate redshift. Wavelength increases up towards the red and beyond (frequency decreases).
Astronomical objectAn astronomical object, celestial object, stellar object or heavenly object is a naturally occurring physical entity, association, or structure that exists within the universe. In astronomy, the terms object and body are often used interchangeably.
Photometry (astronomy)In astronomy, photometry, from Greek photo- ("light") and -metry ("measure"), is a technique used in astronomy that is concerned with measuring the flux or intensity of light radiated by astronomical objects. This light is measured through a telescope using a photometer, often made using electronic devices such as a CCD photometer or a photoelectric photometer that converts light into an electric current by the photoelectric effect.
GalaxyA galaxy is a physical system of stars, planetary systems, stellar remnants, substellar objects, interstellar gas, dust, and dark matter bound together by gravity. The word is derived from the Greekgalaxias (γαλαξίας), meaning 'milky', a reference to the Milky Way galaxy that contains the Solar System.
WavelengthIn physics and mathematics, wavelength or spatial period of a wave or periodic function is the distance over which the wave's shape repeats. In other words, it is the distance between consecutive corresponding points of the same phase on the wave, such as two adjacent crests, troughs, or zero crossings. Wavelength is a characteristic of both traveling waves and standing waves, as well as other spatial wave patterns.
Hubble's lawHubble's law, officially the Hubble–Lemaître law, is the observation in physical cosmology that galaxies are moving away from Earth at speeds proportional to their distance. Thus, the farther a galaxy is from the Earth, the faster it moves away. A galaxy's recessional velocity is typically determined by measuring its redshift, a shift in the frequency of light emitted by the galaxy.
PassbandA passband is the range of frequencies or wavelengths that can pass through a filter. For example, a radio receiver contains a bandpass filter to select the frequency of the desired radio signal out of all the radio waves picked up by its antenna. The passband of a receiver is the range of frequencies it can receive when it is tuned into the desired frequency as in a radio station or television channel.FrequencyFrequency is the number of occurrences of a repeating event per unit of time. Frequency is an important parameter used in science and engineering to specify the rate of oscillatory and vibratory phenomena, such as mechanical vibrations, audio signals (sound), radio waves, and light. The interval of time between events is called the period. It is the reciprocal of the frequency.
Optical filterAn optical filter is a device that selectively transmitslight of different wavelengths, usually implemented as a glass plane or plastic device in the optical path, which are either dyed in the bulk or have interference coatings. The optical properties of filters are completely described by their frequency response, which specifies how the magnitude and phase of each frequency component of an incoming signal is modified by the filter.*As an Amazon Associate I earn from qualifying purchases.