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  2. Radial velocity - Wikipedia

    en.wikipedia.org/wiki/Radial_Velocity

    A positive radial velocity indicates the distance between the objects is or was increasing; a negative radial velocity indicates the distance between the source and observer is or was decreasing. William Huggins ventured in 1868 to estimate the radial velocity of Sirius with respect to the Sun, based on observed redshift of the star's light. [6]

  3. Doppler spectroscopy - Wikipedia

    en.wikipedia.org/wiki/Doppler_spectroscopy

    Doppler spectroscopy (also known as the radial-velocity method, or colloquially, the wobble method) is an indirect method for finding extrasolar planets and brown dwarfs from radial-velocity measurements via observation of Doppler shifts in the spectrum of the planet's parent star. As of November 2022, about 19.5% of known extrasolar planets ...

  4. Binary mass function - Wikipedia

    en.wikipedia.org/wiki/Binary_mass_function

    Radial velocity curve with peak radial velocity K=1 m/s and orbital period 2 years. The peak radial velocity is the semi-amplitude of the radial velocity curve, as shown in the figure. The orbital period is found from the periodicity in the radial velocity curve. These are the two observable quantities needed to calculate the binary mass function.

  5. Velocity dispersion - Wikipedia

    en.wikipedia.org/wiki/Velocity_dispersion

    Radial velocity is found by measuring the Doppler width of spectral lines of a collection of objects; the more radial velocities one measures, the more accurately one knows their dispersion. A central velocity dispersion refers to the σ of the interior regions of an extended object, such as a galaxy or cluster.

  6. Proper motion - Wikipedia

    en.wikipedia.org/wiki/Proper_motion

    Barnard's Star's transverse speed is 90 km/s and its radial velocity is 111 km/s (perpendicular (at a right, 90° angle), which gives a true or "space" motion of 142 km/s. True or absolute motion is more difficult to measure than the proper motion, because the true transverse velocity involves the product of the proper motion times the distance.

  7. Minimum mass - Wikipedia

    en.wikipedia.org/wiki/Minimum_mass

    In astronomy, minimum mass is the lower-bound calculated mass of observed objects such as planets, stars, binary systems, [1] nebulae, [2] and black holes.. Minimum mass is a widely cited statistic for extrasolar planets detected by the radial velocity method or Doppler spectroscopy, and is determined using the binary mass function.

  8. Vector fields in cylindrical and spherical coordinates

    en.wikipedia.org/wiki/Vector_fields_in...

    Vectors are defined in cylindrical coordinates by (ρ, φ, z), where . ρ is the length of the vector projected onto the xy-plane,; φ is the angle between the projection of the vector onto the xy-plane (i.e. ρ) and the positive x-axis (0 ≤ φ < 2π),

  9. Tangential speed - Wikipedia

    en.wikipedia.org/wiki/Tangential_speed

    When proper units are used for tangential speed v, rotational speed ω, and radial distance r, the direct proportion of v to both r and ω becomes the exact equation =. This comes from the following: the linear (tangential) velocity of an object in rotation is the rate at which it covers the circumference's length: