Stars
As the light emitted from a star passes through the different layers of Earth’s atmosphere, turbulence causes the starlight to bend. To an observer on Earth, this distortion of the starlight makes the star appear to be "twinkling." Radial velocity is measured by the doppler shift of the star's spectral lines and is given in units of km/s. The proper motion of a star, its parallax, is determined by precise astrometric measurements in units of milli-arc seconds (mas) per year. With knowledge of the star's parallax and its distance, the proper motion velocity can be calculated. The motion of a star relative to the Sun can provide useful information about the origin and age of a star, as well as the structure and evolution of the surrounding galaxy. The components of motion of a star consist of the radial velocity toward or away from the Sun, and the traverse angular movement, which is called its proper motion.
Giant stars have much lower surface gravity than do main-sequence stars, while the opposite is the case for degenerate, compact stars such as white dwarfs. Young, rapidly rotating stars tend to have high levels of surface activity because of their magnetic field. The magnetic field can act upon a star's stellar wind, functioning as a brake to gradually slow the rate of rotation with time. Thus, older stars such as the Sun have a much slower rate of rotation and a lower level of surface activity.
JWST was essential for the observations because its 6.5-meter (21 feet) mirror allows it to catch faint objects at incredible distances, Visbal said. But what helped LAP1-B pop into view was a phenomenon called gravitational lensing, which happens when a very massive object, such as a galaxy, bends space-time around it while a background object is in just the right spot.
As the light emitted from a star passes through the different layers of Earth’s atmosphere, turbulence causes the starlight to bend. To an observer on Earth, this distortion of the starlight makes the star appear to be "twinkling." Radial velocity is measured by the doppler shift of the star's spectral lines and is given in units of km/s. The proper motion of a star, its parallax, is determined by precise astrometric measurements in units of milli-arc seconds (mas) per year. With knowledge of the star's parallax and its distance, the proper motion velocity can be calculated. The motion of a star relative to the Sun can provide useful information about the origin and age of a star, as well as the structure and evolution of the surrounding galaxy. The components of motion of a star consist of the radial velocity toward or away from the Sun, and the traverse angular movement, which is called its proper motion.
Giant stars have much lower surface gravity than do main-sequence stars, while the opposite is the case for degenerate, compact stars such as white dwarfs. Young, rapidly rotating stars tend to have high levels of surface activity because of their magnetic field. The magnetic field can act upon a star's stellar wind, functioning as a brake to gradually slow the rate of rotation with time. Thus, older stars such as the Sun have a much slower rate of rotation and a lower level of surface activity.
JWST was essential for the observations because its 6.5-meter (21 feet) mirror allows it to catch faint objects at incredible distances, Visbal said. But what helped LAP1-B pop into view was a phenomenon called gravitational lensing, which happens when a very massive object, such as a galaxy, bends space-time around it while a background object is in just the right spot.