98 relations: Abell 39, Andromeda Galaxy, Antoine Darquier de Pellepoix, Astronomical spectroscopy, Asymptotic giant branch, Atmosphere of Earth, Binary star, Bipolar nebula, Bulge (astronomy), Carbon, Cat's Eye Nebula, Charge-coupled device, Charles Messier, Chemistry, Continuum (measurement), Cosmic distance ladder, Density, Doppler effect, Doubly ionized oxygen, Dumbbell Nebula, Electron, Emission nebula, Emission spectrum, Energy level, Excited state, Fast Low-Ionization Emission Region, Forbidden mechanism, Galactic Center, Galactic plane, Galaxy, Galaxy formation and evolution, Globular cluster, Helium, Henry Norris Russell, History of the telescope, Hubble Space Telescope, Hydrogen, Infrared, Interstellar medium, Ionization, Jérôme Lalande, Kelvin, Light-year, List of planetary nebulae, Magnetic field, Main sequence, Messier 15, Messier 22, Messier 46, Messier object, ..., Metallicity, Metastability, Milky Way, Misnomer, Monthly Notices of the Royal Astronomical Society, Nanometre, Nebula, Nebulium, NGC 2818, NGC 6441, Nitrogen, Nova remnant, Nuclear fusion, Open cluster, Optical resolution, Oxygen, Palomar 6, PG 1159 star, Photon, Planet, Plasma (physics), Prism, Protoplanetary nebula, Radiation, Red giant, Ring Nebula, Saturn Nebula, Solar mass, Space telescope, Spectral line, Star, Stellar classification, Stellar evolution, Stellar population, Stellar wind, Sun, Supernova, Supernova remnant, Temperature, The Astrophysical Journal, Ultraviolet, Universe, Uranus, Visible spectrum, Vulpecula, White dwarf, William Herschel, William Huggins. Expand index (48 more) » « Shrink index
Abell 39 is a low surface brightness planetary nebula in the constellation of Hercules.
The Andromeda Galaxy, also known as Messier 31, M31, or NGC 224, is a spiral galaxy approximately 780 kiloparsecs (2.5 million light-years) from Earth, and the nearest major galaxy to the Milky Way.
Antoine Darquier de Pellepoix (23 November 1718, in Toulouse – 18 January 1802, in Toulouse) was a French astronomer.
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.
The asymptotic giant branch (AGB) is a region of the Hertzsprung–Russell diagram populated by evolved cool luminous stars.
The atmosphere of Earth is the layer of gases, commonly known as air, that surrounds the planet Earth and is retained by Earth's gravity.
A binary star is a star system consisting of two stars orbiting around their common barycenter.
A bipolar nebula is a distinctive nebular formation characterized by an axially symmetric bi-lobed appearance.
In astronomy, a bulge is a tightly packed group of stars within a larger formation.
Carbon (from carbo "coal") is a chemical element with symbol C and atomic number 6.
The Cat's Eye Nebula or NGC 6543, is a relatively bright planetary nebula in the northern constellation of Draco, discovered by William Herschel on February 15, 1786.
A charge-coupled device (CCD) is a device for the movement of electrical charge, usually from within the device to an area where the charge can be manipulated, for example conversion into a digital value.
Charles Messier (26 June 1730 – 12 April 1817) was a French astronomer most notable for publishing an astronomical catalogue consisting of nebulae and star clusters that came to be known as the 110 "Messier objects".
Chemistry is the scientific discipline involved with compounds composed of atoms, i.e. elements, and molecules, i.e. combinations of atoms: their composition, structure, properties, behavior and the changes they undergo during a reaction with other compounds.
Continuum theories or models explain variation as involving gradual quantitative transitions without abrupt changes or discontinuities.
The cosmic distance ladder (also known as the extragalactic distance scale) is the succession of methods by which astronomers determine the distances to celestial objects.
The density, or more precisely, the volumetric mass density, of a substance is its mass per unit volume.
The Doppler effect (or the Doppler shift) is the change in frequency or wavelength of a wave in relation to observer who is moving relative to the wave source.
In astronomy and atomic physics, doubly ionized oxygen is the ion O2+ (also known as O III in spectroscopic notation).
The Dumbbell Nebula (also known as Apple Core Nebula, Messier 27, M 27, or NGC 6853) is a planetary nebula in the constellation Vulpecula, at a distance of about 1,360 light-years.
The electron is a subatomic particle, symbol or, whose electric charge is negative one elementary charge.
An emission nebula is a nebula formed of ionized gases that emit light of various wavelengths.
The emission spectrum of a chemical element or chemical compound is the spectrum of frequencies of electromagnetic radiation emitted due to an atom or molecule making a transition from a high energy state to a lower energy state.
A quantum mechanical system or particle that is bound—that is, confined spatially—can only take on certain discrete values of energy.
In quantum mechanics, an excited state of a system (such as an atom, molecule or nucleus) is any quantum state of the system that has a higher energy than the ground state (that is, more energy than the absolute minimum).
A Fast Low-Ionization Emission Region, or FLIER, is a volume of gas with low ionization, moving at supersonic speeds, near the symmetry axis of many planetary nebulae.
In spectroscopy, a forbidden mechanism (forbidden transition or forbidden line) is a spectral line associated with absorption or emission of light by atomic nuclei, atoms, or molecules which undergo a transition that is not allowed by a particular selection rule but is allowed if the approximation associated with that rule is not made.
The Galactic Center is the rotational center of the Milky Way.
The galactic plane is the plane on which the majority of a disk-shaped galaxy's mass lies.
A galaxy is a gravitationally bound system of stars, stellar remnants, interstellar gas, dust, and dark matter.
The study of galaxy formation and evolution is concerned with the processes that formed a heterogeneous universe from a homogeneous beginning, the formation of the first galaxies, the way galaxies change over time, and the processes that have generated the variety of structures observed in nearby galaxies.
A globular cluster is a spherical collection of stars that orbits a galactic core as a satellite.
Helium (from lit) is a chemical element with symbol He and atomic number 2.
Prof Henry Norris Russell FRS(For) HFRSE FRAS (October 25, 1877 – February 18, 1957) was an American astronomer who, along with Ejnar Hertzsprung, developed the Hertzsprung–Russell diagram (1910).
The earliest known telescope appeared in 1608 in the Netherlands when an eyeglass maker named Hans Lippershey tried to obtain a patent on one.
The Hubble Space Telescope (HST) is a space telescope that was launched into low Earth orbit in 1990 and remains in operation.
Hydrogen is a chemical element with symbol H and atomic number 1.
Infrared radiation (IR) is electromagnetic radiation (EMR) with longer wavelengths than those of visible light, and is therefore generally invisible to the human eye (although IR at wavelengths up to 1050 nm from specially pulsed lasers can be seen by humans under certain conditions). It is sometimes called infrared light.
In astronomy, the interstellar medium (ISM) is the matter and radiation that exists in the space between the star systems in a galaxy.
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.
Joseph Jérôme Lefrançois de Lalande (11 July 1732 – 4 April 1807) was a French astronomer, freemason and writer.
The Kelvin scale is an absolute thermodynamic temperature scale using as its null point absolute zero, the temperature at which all thermal motion ceases in the classical description of thermodynamics.
The light-year is a unit of length used to express astronomical distances and measures about 9.5 trillion kilometres or 5.9 trillion miles.
The following is an incomplete list of known planetary nebulae.
A magnetic field is a vector field that describes the magnetic influence of electrical currents and magnetized materials.
In astronomy, the main sequence is a continuous and distinctive band of stars that appear on plots of stellar color versus brightness.
Messier 15 or M15 (also designated NGC 7078) is a globular cluster in the constellation Pegasus.
Messier 22 (also known as M22 or NGC 6656) is an elliptical globular cluster in the constellation Sagittarius, near the Galactic bulge region.
Messier 46 (also known as M 46 or NGC 2437) is an open cluster in the constellation of Puppis.
The Messier objects are a set of 110 astronomical objects, of which 103 were included in lists published by French astronomer Charles Messier in 1771 and 1781.
In astronomy, metallicity is used to describe the abundance of elements present in an object that are heavier than hydrogen or helium.
In physics, metastability is a stable state of a dynamical system other than the system's state of least energy.
The Milky Way is the galaxy that contains our Solar System.
A misnomer is a name or term that suggests an idea that is known to be wrong.
Monthly Notices of the Royal Astronomical Society (MNRAS) is a peer-reviewed scientific journal covering research in astronomy and astrophysics.
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 (short scale) of a metre (m).
A nebula (Latin for "cloud" or "fog"; pl. nebulae, nebulæ, or nebulas) is an interstellar cloud of dust, hydrogen, helium and other ionized gases.
Nebulium was a proposed element found in astronomical observation of a nebula by William Huggins in 1864.
NGC 2818 is a planetary nebula located in the southern constellation Pyxis (The Compass).
NGC 6441 is the New General Catalogue identifier for a globular cluster in the southern constellation of Scorpius.
Nitrogen is a chemical element with symbol N and atomic number 7.
A nova remnant is made up of the material either left behind by a sudden explosive fusion eruption by classical novae, or from multiple ejections by recurrent novae.
In nuclear physics, nuclear fusion is a reaction in which two or more atomic nuclei come close enough to form one or more different atomic nuclei and subatomic particles (neutrons or protons).
An open cluster is a group of up to a few thousand stars that were formed from the same giant molecular cloud and have roughly the same age.
Optical resolution describes the ability of an imaging system to resolve detail in the object that is being imaged.
Oxygen is a chemical element with symbol O and atomic number 8.
Palomar 6 is a loose globular cluster in the constellation Ophiuchus that belongs to the halo of the Milky Way galaxy.
A PG 1159 star, often also called a pre-degenerate, is a star with a hydrogen-deficient atmosphere that is in transition between being the central star of a planetary nebula and being a hot white dwarf.
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).
A planet is an astronomical body orbiting a star or stellar remnant that is massive enough to be rounded by its own gravity, is not massive enough to cause thermonuclear fusion, and has cleared its neighbouring region of planetesimals.
Plasma (Henry George Liddell, Robert Scott, A Greek English Lexicon, on Perseus) is one of the four fundamental states of matter, and was first described by chemist Irving Langmuir in the 1920s.
In optics, a prism is a transparent optical element with flat, polished surfaces that refract light.
A protoplanetary nebula or preplanetary nebula (PPN) is an astronomical object which is at the short-lived episode during a star's rapid evolution between the late asymptotic giant branch (LAGB) phase and the subsequent planetary nebula (PN) phase.
In physics, radiation is the emission or transmission of energy in the form of waves or particles through space or through a material medium.
A red giant is a luminous giant star of low or intermediate mass (roughly 0.3–8 solar masses) in a late phase of stellar evolution.
The Ring Nebula (also catalogued as Messier 57, M57 or NGC 6720) is a planetary nebula in the northern constellation of Lyra.
The Saturn Nebula or NGC 7009 is a planetary nebula in the constellation Aquarius.
The solar mass is a standard unit of mass in astronomy, equal to approximately.
A space telescope or space observatory is an instrument located in outer space to observe distant planets, galaxies and other astronomical objects.
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.
A star is type of astronomical object consisting of a luminous spheroid of plasma held together by its own gravity.
In astronomy, stellar classification is the classification of stars based on their spectral characteristics.
Stellar evolution is the process by which a star changes over the course of time.
During 1944, Walter Baade categorized groups of stars within the Milky Way into bluer stars associated with the spiral arms and the general position of yellow stars near the central galactic bulge or within globular star clusters.
A stellar wind is a flow of gas ejected from the upper atmosphere of a star.
The Sun is the star at the center of the Solar System.
A supernova (plural: supernovae or supernovas, abbreviations: SN and SNe) is a transient astronomical event that occurs during the last stellar evolutionary stages of a star's life, either a massive star or a white dwarf, whose destruction is marked by one final, titanic explosion.
A supernova remnant (SNR) is the structure resulting from the explosion of a star in a supernova.
Temperature is a physical quantity expressing hot and cold.
The Astrophysical Journal, often abbreviated ApJ (pronounced "ap jay") in references and speech, is a peer-reviewed scientific journal of astrophysics and astronomy, established in 1895 by American astronomers George Ellery Hale and James Edward Keeler.
Ultraviolet (UV) is electromagnetic radiation with a wavelength from 10 nm to 400 nm, shorter than that of visible light but longer than X-rays.
The Universe is all of space and time and their contents, including planets, stars, galaxies, and all other forms of matter and energy.
Uranus is the seventh planet from the Sun.
The visible spectrum is the portion of the electromagnetic spectrum that is visible to the human eye.
Vulpecula is a faint constellation in the northern sky.
A white dwarf, also called a degenerate dwarf, is a stellar core remnant composed mostly of electron-degenerate matter.
Frederick William Herschel, (Friedrich Wilhelm Herschel; 15 November 1738 – 25 August 1822) was a German-born British astronomer, composer and brother of fellow astronomer Caroline Herschel, with whom he worked.
Sir William Huggins (7 February 1824 – 12 May 1910) was an English astronomer best known for his pioneering work in astronomical spectroscopy together with his wife Margaret Lindsay Huggins.