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  2. Photometric system - Wikipedia

    en.wikipedia.org/wiki/Photometric_system

    Photometric system. In astronomy, a photometric system is a set of well-defined passbands (or optical filters ), with a known sensitivity to incident radiation. The sensitivity usually depends on the optical system, detectors and filters used. For each photometric system a set of primary standard stars is provided.

  3. Radio astronomy - Wikipedia

    en.wikipedia.org/wiki/Radio_astronomy

    Radio astronomy. The Karl G. Jansky Very Large Array, a radio interferometer in New Mexico, United States. Radio astronomy is a subfield of astronomy that studies celestial objects at radio frequencies. The first detection of radio waves from an astronomical object was in 1933, when Karl Jansky at Bell Telephone Laboratories reported radiation ...

  4. Electromagnetic spectrum - Wikipedia

    en.wikipedia.org/wiki/Electromagnetic_spectrum

    The electromagnetic spectrum is the full range of electromagnetic radiation, organized by frequency or wavelength. The spectrum is divided into separate bands, with different names for the electromagnetic waves within each band. From low to high frequency these are: radio waves, microwaves, infrared, visible light, ultraviolet, X-rays, and ...

  5. Stellar classification - Wikipedia

    en.wikipedia.org/wiki/Stellar_classification

    The strengths of the different spectral lines vary mainly due to the temperature of the photosphere, although in some cases there are true abundance differences. The spectral class of a star is a short code primarily summarizing the ionization state, giving an objective measure of the photosphere's temperature.

  6. Stellar evolution - Wikipedia

    en.wikipedia.org/wiki/Stellar_evolution

    Representative lifetimes of stars as a function of their masses The change in size with time of a Sun-like star Artist's depiction of the life cycle of a Sun-like star, starting as a main-sequence star at lower left then expanding through the subgiant and giant phases, until its outer envelope is expelled to form a planetary nebula at upper right Chart of stellar evolution

  7. List of Christian denominations by number of members

    en.wikipedia.org/wiki/List_of_Christian...

    Anglican Episcopal Church of Brazil – 0.1 million [59] Anglican Church of Mexico – 0.1 million. Church of the Province of South East Asia – 0.1 million. Anglican Church of Korea – 0.1 million [60] Spanish Reformed Episcopal Church – 0.005 million. Lusitanian Catholic Apostolic Evangelical Church – 0.005 million.

  8. Color–color diagram - Wikipedia

    en.wikipedia.org/wiki/Color–color_diagram

    A color–color diagram is a means of comparing the colors of an astronomical object at different wavelengths. Astronomers typically observe at narrow bands around certain wavelengths, and objects observed will have different brightnesses in each band. The difference in brightness between two bands is referred to as an object's color index, or ...

  9. List of states of matter - Wikipedia

    en.wikipedia.org/wiki/List_of_states_of_matter

    In common temperatures and pressures, atoms form the three classical states of matter: solid, liquid and gas. Complex molecules can also form various mesophases such as liquid crystals, which are intermediate between the liquid and solid phases. At high temperatures or strong electromagnetic fields atoms become ionized, forming plasma .