Solar luminosity in the context of Robert Quimby

Luminosity is an absolute measure of radiated electromagnetic energy per unit time, and is synonymous with the radiant power emitted by a light-emitting object. In astronomy, luminosity is the total amount of electromagnetic energy emitted per unit of time by a star, galaxy, or other astronomical objects.

In SI units, luminosity is measured in joules per second, or watts. In astronomy, values for luminosity are often given in the terms of the luminosity of the Sun, L_⊙. Luminosity can also be given in terms of the astronomical magnitude system: the absolute bolometric magnitude (M_bol) of an object is a logarithmic measure of its total energy emission rate, while absolute magnitude is a logarithmic measure of the luminosity within some specific wavelength range or filter band.

Beta Fornacis (Beta For, β Fornacis, β For) is solitary star in the southern constellation of Fornax. It is visible to the naked eye with an apparent visual magnitude of 4.46. Based upon an annual parallax shift of 18.46 mas, it is located around 177 light years away from the Sun. At that distance, the visual magnitude is reduced by an interstellar extinction factor of 0.1.

This is an evolved, G-type giant star with a stellar classification of G8 III. It is a red clump giant, which means it has undergone helium flash and is currently generating energy through the fusion of helium at its core. Beta Fornacis has 1.33 times the mass of the Sun and, at an age of 3.3 billion years, has expanded to 10.5 times the Sun's radius. It is radiating 51 times the solar luminosity from its outer atmosphere at an effective temperature of 4,790 K.

Rigel is a blue supergiant star in the equatorial constellation of Orion. It has the Bayer designation β Orionis, which is Latinized to Beta Orionis and abbreviated Beta Ori or β Ori. Rigel is the brightest and most massive component – and the eponym – of a star system of at least four stars that appear as a single blue-white point of light to the naked eye. This system is located at a distance of approximately 850 light-years (260 pc).

A star of spectral type B8Ia, Rigel is calculated to be anywhere from 61,500 to 363,000 times as luminous as the Sun, and 18 to 24 times as massive, depending on the method and assumptions used. Its radius is more than seventy times that of the Sun, and its surface temperature is 12,100 K. Due to its stellar wind, Rigel's mass-loss is estimated to be ten million times that of the Sun. With an estimated age of seven to nine million years, Rigel has exhausted its core hydrogen fuel, expanded, and cooled to become a supergiant. It is expected to end its life as a type II supernova, leaving a neutron star or a black hole as a final remnant, depending on the initial mass of the star.

Orion's Belt is an asterism in the constellation of Orion. Other names include the Belt of Orion, the Three Kings, and the Three Sisters. The belt consists of three bright and easily identifiable collinear star systems – Alnitak, Alnilam, and Mintaka – nearly equally spaced in a line, spanning an angular size of ~140′ (2.3°).

Owing to the high surface temperatures of their constituent stars, the intense light emitted is blue-white in color. In spite of their spot-like appearance, only Alnilam is a single star; Alnitak is a triple star system, and Mintaka a sextuple. All three owe their luminosity to the presence of one or more blue supergiants. The brightest as viewed from the Sun is Alnilam, with an apparent magnitude of 1.69, followed by Alnitak at 1.74 and Mintaka at 2.25. The ten stars of the three systems have a combined luminosity approximately a million times that of the Sun.

Deneb (/ˈdɛnɛb/) is a blue supergiant star in the constellation of Cygnus. It is the brightest star in the constellation and the 19th brightest in the night sky, with an apparent magnitude slightly varying between +1.21 and +1.29. Deneb is one of the vertices of the asterism known as the Summer Triangle and the "head" of the Northern Cross. Its Bayer designation is α Cygni, which is Latinised to Alpha Cygni, abbreviated to Alpha Cyg or α Cyg.

Deneb rivals Rigel, a closer blue supergiant, as the most luminous first-magnitude star. However, its distance, and hence luminosity, is poorly known; its luminosity is estimated to be between 55,000 and 196,000 times that of the Sun. Distance estimates range from 1,400 to 2,600 light-years; assuming its highest value, it is the farthest star with an apparent magnitude brighter than 2.50.

Aldebaran (Arabic: الدَّبَران, lit. 'The Follower') is a star in the zodiac constellation of Taurus. It has the Bayer designation α Tauri, which is Latinized to Alpha Tauri and abbreviated Alpha Tau or α Tau. Aldebaran varies in brightness from an apparent visual magnitude of 0.75 down to 0.95, making it the brightest star in the constellation, as well as (typically) the fourteenth-brightest star in the night sky. It is at a distance of approximately 67 light-years. The star lies along the line of sight to the nearby Hyades cluster, but is unrelated and much older than the young cluster.

Aldebaran is a red giant, meaning that it is cooler than the Sun with a surface temperature of 3,900 K, but its radius is about 45 times the Sun's, so it is over 400 times as luminous. As a giant star, it has moved off the main sequence on the Hertzsprung–Russell diagram after depleting its supply of hydrogen in the core. The star spins slowly and takes 520 days to complete a rotation.

HUDF-JD2 (UDF 033238.7 -274839.8 or BBG 3179) is a distant, massive, post-starburst galaxythat was discovered with the Hubble Ultra Deep Field (HUDF) image. It was the most distant galaxy identified in the HUDF, in 2005. It is located at 03 32 38.7268 −27° 48′ 39.885″ in the constellation of Fornax.

In a 2005 search for very red galaxies in the HUDF that were not detected at wavelengths shorter than the near-infrared J band, two objects were detected. The second, initially designated UDF033238.7-274839.8, displayed a high redshift and showed characteristics of a post-starburst galaxy. The derived photometric redshift yielded z approximately equal to 6.5, which indicates it is most likely being viewed from a time when the Universe was only 830 million years old. The estimated bolometric luminosity of this galaxy is a trillion times the solar luminosity (the luminosity of the Sun) and it has a mass of approximately 600 billion solar masses.

Alnilam is the central star of Orion's Belt in the equatorial constellation of Orion. It has the Bayer designation ε Orionis, which is Latinised to Epsilon Orionis and abbreviated Epsilon Ori or ε Ori. This is a massive, blue supergiant star some 1,250 light-years distant. It is estimated to be 270,000 times as luminous as the Sun, and 28 times as massive.

Luminous infrared galaxies or LIRGs are galaxies with luminosities above 10 L_☉. They are also referred to as submillimeter galaxies (SMGs) through their normal method of detection. LIRGs are more abundant than starburst galaxies, Seyfert galaxies and quasi-stellar objects at comparable luminosity. Infrared galaxies emit more energy in the infrared than at all other wavelengths combined. A LIRG's luminosity is 100 billion times that of the Sun.

Galaxies with luminosities above 10 L_☉ are known as ultraluminous infrared galaxies (ULIRGs). Galaxies exceeding 10 L_☉ are characterised as hyper-luminous infrared galaxies (HyLIRGs). Those exceeding 10 L_☉ are extremely luminous infrared galaxies (ELIRGs). Many of the LIRGs and ULIRGs are showing interactions and disruptions. Many of these types of galaxies spawn about 100 new stars a year as compared to the Milky Way which spawns one a year; this helps create the high level of luminosity.

Phi Geminorum, Latinized from φ Geminorum, is a binary star in the constellation Gemini, to the southeast of Pollux. It is visible to the naked eye with an apparent visual magnitude of 4.95. Based upon an annual parallax shift of 14.66 mas, this system is located around 220 light years from the Sun.

The two components of this system have a circular orbit with a period of 582 days. The primary component is an A-type main sequence star with a stellar classification of A3 V. It is around 600 million years old and spinning relatively rapidly with a projected rotational velocity of 165 km/s. This rate of spin is giving the star an oblate shape with an equatorial bulge that is 6% larger than the polar radius. The star has nearly double the mass of the Sun and radiates 36.5 times the solar luminosity from its outer atmosphere at an effective temperature of 8,551 K.