Eridanus (constellation)Eridanus (ᵻˈrɪdənəs) is a constellation in the southern celestial hemisphere. It is represented as a river. One of the 48 constellations listed by the 2nd century astronomer Ptolemy, it remains one of the 88 modern constellations. It is the sixth largest of the modern constellations, and the one that extends farthest in the sky from north to south. The same name was later taken as a Latin name for the real Po River and also for the name of a minor river in Athens. List of stars in Eridanus At its southern end is the magnitude 0.
CanopusCanopus is the brightest star in the southern constellation of Carina and the second-brightest star in the night sky. It is also designated α Carinae, which is Latinised to Alpha Carinae. With a visual apparent magnitude of −0.74, it is outshone only by Sirius. Located around 310light-years from the Sun, Canopus is a bright giant of spectral type A9, so it is essentially white when seen with the naked eye. It has a luminosity over 10,000 times the luminosity of the Sun, is eight times as massive, and has expanded to 71 times the Sun's radius.
Orion (constellation)Orion is a prominent constellation during winter in the northern celestial hemisphere. It is one of the 88 modern constellations; it was among the 48 constellations listed by the 2nd-century astronomer Ptolemy. It is named for a mythological hunter in Greek mythology. Orion is most prominent during winter evenings in the Northern Hemisphere, as are five other constellations that have stars in the Winter Hexagon asterism. Its two brightest stars, Rigel (β) and Betelgeuse (α), are both among the brightest stars in the night sky; both are supergiants and slightly variable.
RegulusRegulus is the brightest object in the constellation Leo and one of the brightest stars in the night sky. It has the Bayer designation designated α Leonis, which is Latinized to Alpha Leonis, and abbreviated Alpha Leo or α Leo. Regulus appears singular, but is actually a quadruple star system composed of four stars that are organized into two pairs. The spectroscopic binary Regulus A consists of a blue-white main-sequence star and its companion, which has not yet been directly observed, but is probably a white dwarf.
SpicaSpica is the brightest object in the constellation of Virgo and one of the 20 brightest stars in the night sky. It has the Bayer designation α Virginis, which is Latinised to Alpha Virginis and abbreviated Alpha Vir or α Vir. Analysis of its parallax shows that it is located 250 light-years from the Sun. It is a spectroscopic binary star and rotating ellipsoidal variable; a system whose two stars are so close together they are egg-shaped rather than spherical, and can only be separated by their spectra.
VegaVega is the brightest star in the northern constellation of Lyra. It has the Bayer designation α Lyrae, which is Latinised to Alpha Lyrae and abbreviated Alpha Lyr or α Lyr. This star is relatively close at only from the Sun, and one of the most luminous stars in the Sun's neighborhood. It is the fifth-brightest star in the night sky, and the second-brightest star in the northern celestial hemisphere, after Arcturus. Vega has been extensively studied by astronomers, leading it to be termed "arguably the next most important star in the sky after the Sun".
DenebDeneb (ˈdɛnɛb) is a first-magnitude star in the constellation of Cygnus. Deneb is one of the vertices of the asterism known as the Summer Triangle and the "head" of the Northern Cross. It is the brightest star in Cygnus and the 19th brightest star in the night sky, with an average apparent magnitude of +1.25. A blue-white supergiant, Deneb rivals Rigel as the most luminous first-magnitude star. However, its distance, and hence luminosity, is poorly known; its luminosity is somewhere between 55,000 and 196,000 times that of the Sun.
Deep-sky objectA deep-sky object (DSO) is any astronomical object that is not an individual star or Solar System object (such as Sun, Moon, planet, comet, etc.). The classification is used for the most part by amateur astronomers to denote visually observed faint naked eye and telescopic objects such as star clusters, nebulae and galaxies. This distinction is practical and technical, implying a variety of instruments and techniques appropriate to observation, and does not distinguish the nature of the object itself.
Arcturus|- bgcolor="#FFFAFA" | Note (category: variability): || H and K emission vary. Arcturus is the brightest star in the northern constellation of Boötes. With an apparent visual magnitude of −0.05, it is the fourth-brightest star in the night sky, and the brightest in the northern celestial hemisphere. The name Arcturus originated from ancient Greece; it was then cataloged as α Boötis by Johann Bayer in 1603, which is Latinized to Alpha Boötis. Arcturus forms one corner of the Spring Triangle asterism.
Circumpolar starA circumpolar star is a star that, as viewed from a given latitude on Earth, never sets below the horizon due to its apparent proximity to one of the celestial poles. Circumpolar stars are therefore visible from said location toward the nearest pole for the entire night on every night of the year (and would be continuously visible throughout the day too, were they not overwhelmed by the Sun's glare). Others are called seasonal stars. All circumpolar stars lie within a circumpolar circle whose size is determined by the observer's latitude.
