| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Aquarius |
| Right ascension | 23h 31m 42.03824s [1] |
| Declination | −21° 22′ 10.0640″ [1] |
| Apparent magnitude (V) | 6.24 [2] |
| Characteristics | |
| Spectral type | F0 V [3] |
| B−V color index | 0.319±0.008 [2] |
| Astrometry | |
| Radial velocity (Rv) | −8.0±7.4 [2] km/s |
| Proper motion (μ) | RA: +0.080 [1] mas/yr Dec.: +5.503 [1] mas/yr |
| Parallax (π) | 13.4715 ± 0.0632 [1] mas |
| Distance | 242 ± 1 ly (74.2 ± 0.3 pc) |
| Absolute magnitude (MV) | 1.83 [2] |
| Details | |
| Mass | 1.83±0.03 [4] M☉ |
| Radius | 2.51+0.41 −0.15 [1] R☉ |
| Luminosity | 15.84+1.27 −1.17 [4] L☉ |
| Temperature | 7,063±49 [4] K |
| Rotational velocity (v sin i) | 123 [4] km/s |
| Other designations | |
| Database references | |
| SIMBAD | data |
100 Aquarii is a star in the zodiac constellation of Aquarius. The designation is from the star catalogue of English astronomer John Flamsteed, first published in 1712. It is near the lower limit of visibility to the naked eye, appearing as a dim, yellow-white hued star with an apparent visual magnitude of 6.24. [2] The heliocentric radial velocity is poorly constrained, but the star appears to be moving closer to the Earth at the rate of around −8 km/s. [2]
A star is an astronomical object consisting of a luminous spheroid of plasma held together by its own gravity. The nearest star to Earth is the Sun. Many other stars are visible to the naked eye from Earth during the night, appearing as a multitude of fixed luminous points in the sky due to their immense distance from Earth. Historically, the most prominent stars were grouped into constellations and asterisms, the brightest of which gained proper names. Astronomers have assembled star catalogues that identify the known stars and provide standardized stellar designations. The observable Universe contains an estimated 1×1024 stars, but most are invisible to the naked eye from Earth, including all stars outside our galaxy, the Milky Way.
The zodiac is an area of the sky that extends approximately 8° north or south of the ecliptic, the apparent path of the Sun across the celestial sphere over the course of the year. The paths of the Moon and visible planets are also within the belt of the zodiac.
A constellation is a group of stars that forms an imaginary outline or pattern on the celestial sphere, typically representing an animal, mythological person or creature, a god, or an inanimate object.
This is an ordinary F-type main-sequence star with a stellar classification of F0 V. [3] The star has a high rate of spin, showing a projected rotational velocity of 123 km/s. [4] It has 1.8 [4] times the mass of the Sun and 2.5 [1] times the Sun's radius. The star is radiating 16 [4] times the luminosity of the Sun from its photosphere at an effective temperature of 7,063 K. [4]
An F-type main-sequence star is a main-sequence, hydrogen-fusing compact star of spectral type F and luminosity class V. These stars have from 1.0 to 1.4 times the mass of the Sun and surface temperatures between 6,000 and 7,600 K.Tables VII and VIII. This temperature range gives the F-type stars a yellow-white hue. Because a main-sequence star is referred to as a dwarf star, this class of star may also be termed a yellow-white dwarf. Famous examples include Procyon A, Gamma Virginis A and B, and KIC 8462852.
In astronomy, stellar classification is the classification of stars based on their spectral characteristics. Electromagnetic radiation from the star is analyzed by splitting it with a prism or diffraction grating into a spectrum exhibiting the rainbow of colors interspersed with spectral lines. Each line indicates a particular chemical element or molecule, with the line strength indicating the abundance of that element. 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.
The photosphere is a star's outer shell from which light is radiated. The term itself is derived from Ancient Greek roots, φῶς, φωτός/phos, photos meaning "light" and σφαῖρα/sphaira meaning "sphere", in reference to it being a spherical surface that is perceived to emit light. It extends into a star's surface until the plasma becomes opaque, equivalent to an optical depth of approximately 2/3, or equivalently, a depth from which 50% of light will escape without being scattered. In other words, a photosphere is the deepest region of a luminous object, usually a star, that is transparent to photons of certain wavelengths.
