An Etymological Dictionary of Astronomy and Astrophysics

The only supernova seen to date in the Andromeda galaxy and the first supernova observed beyond our own Galaxy. It was recorded on Aug. 20, 1885, by Ernst Hartwig (1851-1923) at Dorpat Observatory (Tartu) in Estonia and independently by other astronomers. S Andromedae reached magnitude 6 between Aug. 17 and 20, and had faded to magnitude 16 by February 1890. It is now believed that S Andromedae was a Type Ia supernova. Also known as SN 1885A.

See also: S, from the second variable star to be discovered in constellation → Andromeda

The only supernova seen to date in the Andromeda galaxy and the first supernova observed beyond our own Galaxy. It was recorded on Aug. 20, 1885, by Ernst Hartwig (1851-1923) at Dorpat Observatory (Tartu) in Estonia and independently by other astronomers. S Andromedae reached magnitude 6 between Aug. 17 and 20, and had faded to magnitude 16 by February 1890. It is now believed that S Andromedae was a Type Ia supernova. Also known as SN 1885A.

See also: S, from the second variable star to be discovered in constellation → Andromeda

A moderately bright type of asteroids (albedo 0.10 to 0.22) consisting mainly of iron- and magnesium-silicates such as olivine and pyroxene. They are dominant in the inner main belt within 2.2 AU, common in the central belt within about 3 AU, but become rare further out. The largest is 15 Eunomia (about 330 km in its largest dimension).

See also: S stands for silicaceous, → silicate;
→ asteroid.

A moderately bright type of asteroids (albedo 0.10 to 0.22) consisting mainly of iron- and magnesium-silicates such as olivine and pyroxene. They are dominant in the inner main belt within 2.2 AU, common in the central belt within about 3 AU, but become rare further out. The largest is 15 Eunomia (about 330 km in its largest dimension).

See also: S stands for silicaceous, → silicate;
→ asteroid.

A → star cluster situated within an arcsecond, or 0.04 pc, from the → Galactic Center, in the vicinity of the → supermassive black hole Sgr A*. The cluster members are about 40 → main sequence → B-type stars with relatively high orbital → eccentricities (0.3 ≤ e&le 0.95). The most famous member of the S cluster is S2 because of its brightness and its fast orbital motion near Sgr A*. Same as Same as the Sgr A* cluster and
S stars. See also other → Galactic center clusters (Figer et al. 2002, ApJ 581, 258; and 1999, ApJ 525, 750).

See also: S, because of proximity to → Sgr A*; → cluster.

A → star cluster situated within an arcsecond, or 0.04 pc, from the → Galactic Center, in the vicinity of the → supermassive black hole Sgr A*. The cluster members are about 40 → main sequence → B-type stars with relatively high orbital → eccentricities (0.3 ≤ e&le 0.95). The most famous member of the S cluster is S2 because of its brightness and its fast orbital motion near Sgr A*. Same as Same as the Sgr A* cluster and
S stars. See also other → Galactic center clusters (Figer et al. 2002, ApJ 581, 258; and 1999, ApJ 525, 750).

See also: S, because of proximity to → Sgr A*; → cluster.

A type of massive, → blue supergiant, → variable star, also known as a → Hubble-Sandage variable or a → Luminous Blue Variable (LBV). S Doradus stars are the most luminous stars in the Galaxy and are easily identified in other nearby galaxies. They are named after the prototype, S Doradus, in the → Large Magellanic Cloud.

See also: → Dorado; → star.

A type of massive, → blue supergiant, → variable star, also known as a → Hubble-Sandage variable or a → Luminous Blue Variable (LBV). S Doradus stars are the most luminous stars in the Galaxy and are easily identified in other nearby galaxies. They are named after the prototype, S Doradus, in the → Large Magellanic Cloud.

See also: → Dorado; → star.

A → red giant of → spectral type S whose spectrum is dominated by → molecular bands arising from → zirconium → oxide (ZrO). S stars also have strong → cyanogen bands and contain spectral lines of → lithium and → technetium. Almost all S stars are → long-period variables.

See also: S, letter of alphabet; → star.

A → red giant of → spectral type S whose spectrum is dominated by → molecular bands arising from → zirconium → oxide (ZrO). S stars also have strong → cyanogen bands and contain spectral lines of → lithium and → technetium. Almost all S stars are → long-period variables.

See also: S, letter of alphabet; → star.

A → nucleosynthesis process by which → chemical elements heavier than → copper are formed through a slow flux of → neutrons absorbed by atomic nuclei (→ neutron-capture element). The → capture of neutrons occurs on time scales that are long enough to enable unstable nuclei to decay via the emission of a → beta particle before absorbing another neutron. Prominent s-process elements include → barium, → zirconium, and → yttrium. See also: → r-process.

See also: s stands for → slow; → process.

A → nucleosynthesis process by which → chemical elements heavier than → copper are formed through a slow flux of → neutrons absorbed by atomic nuclei (→ neutron-capture element). The → capture of neutrons occurs on time scales that are long enough to enable unstable nuclei to decay via the emission of a → beta particle before absorbing another neutron. Prominent s-process elements include → barium, → zirconium, and → yttrium. See also: → r-process.

See also: s stands for → slow; → process.

A type of → asteroid containing → pyroxene and → olivine silicates, probably mixed with metallic iron, similar to → stony meteorites. S-type asteroids show high albedo of 0.10-0.22. They include about 17% of known asteroids and occupy the inner → asteroid belt.

See also: S for → stone; → type; → asteroid.

A type of → asteroid containing → pyroxene and → olivine silicates, probably mixed with metallic iron, similar to → stony meteorites. S-type asteroids show high albedo of 0.10-0.22. They include about 17% of known asteroids and occupy the inner → asteroid belt.

See also: S for → stone; → type; → asteroid.

Same as → S star.

See also: S, letter of alphabet; → type; → star.

Same as → S star.

See also: S, letter of alphabet; → type; → star.

→ shear wave.

See also: S, referring to → shear; → wave.

→ shear wave.

See also: S, referring to → shear; → wave.

The fastest → main sequence  → hypervelocity star (HVS) with a → heliocentric  → radial velocity of 1017 ±2.7 km s^-1.

The star S5-HVS1 is an → A-type with a → luminosity of ~ 2.35 Msun located at a distance of ~ 9 kpc from the Sun. The current 3D velocity of the star in the Galactic frame is 1755 ± 50 km s^-1. When integrated backwards in time, the orbit of the star points unambiguously to the → Galactic Center, implying that S5-HVS1 was kicked away from → Sgr A* with a velocity of ~ 1800 km s^-1 and travelled for 4.8 Myr to its current location. This is so far the only HVS confidently associated with the Galactic Center. The ejection trajectory and transit time of S5-HVS1 coincide with the orbital plane and age of the annular disk of young stars at the Galactic Centre, and thus may be linked to its formation. With the S5-HVS1 ejection velocity being almost twice the velocity of other hypervelocity stars previously associated with the Galactic Center, the question arises whether they have been generated by the same mechanism or whether the ejection velocity distribution has been constant over time (Koposov, S.E., et al., 2019, arXiv:1907.11725).

See also: S5, or S⁵, short for Southern Stellar Stream Spectroscopic Survey; HVS, → hypervelocity star (HVS).

The fastest → main sequence  → hypervelocity star (HVS) with a → heliocentric  → radial velocity of 1017 ±2.7 km s^-1.

The star S5-HVS1 is an → A-type with a → luminosity of ~ 2.35 Msun located at a distance of ~ 9 kpc from the Sun. The current 3D velocity of the star in the Galactic frame is 1755 ± 50 km s^-1. When integrated backwards in time, the orbit of the star points unambiguously to the → Galactic Center, implying that S5-HVS1 was kicked away from → Sgr A* with a velocity of ~ 1800 km s^-1 and travelled for 4.8 Myr to its current location. This is so far the only HVS confidently associated with the Galactic Center. The ejection trajectory and transit time of S5-HVS1 coincide with the orbital plane and age of the annular disk of young stars at the Galactic Centre, and thus may be linked to its formation. With the S5-HVS1 ejection velocity being almost twice the velocity of other hypervelocity stars previously associated with the Galactic Center, the question arises whether they have been generated by the same mechanism or whether the ejection velocity distribution has been constant over time (Koposov, S.E., et al., 2019, arXiv:1907.11725).

See also: S5, or S⁵, short for Southern Stellar Stream Spectroscopic Survey; HVS, → hypervelocity star (HVS).