Greensboro Traffic Cameras, What Happened To Matthew On Dr Phil, Byrd Funeral Home Dothan, Al Obituaries, Comcast Down Detector Map, Articles S

On the Main Sequence, the more massive stars are bigger, hotter, more luminous, and die faster. The star is designated Canis Majoris, Latinized to Alpha Canis Majoris, and abbreviated CMa or AlphaCMa. e. SIZE OF PEBBLES/SEDIMENTS =, What is the optimum pH for stomach protease? [81] The Voyager 2 spacecraft, launched in 1977 to study the four giant planets in the Solar System, is expected to pass within 4.3 light-years (1.3pc) of Sirius in approximately 296,000 years. There are no exoplanets recorded on the site for the star, and that is most likely the case. , Apparent brightness Read more about the double stars Sirius and Albireo here. All messages will be reviewed before being displayed. In between being a Main Sequence star and its present state, it would've first grown in size and then thrown off its mass in the form of solar winds as a Planetary Nebula which has since dispersed. Your email address will only be used for EarthSky content. It's luminosity is 22.4 (22.4 times that of our sun). R_ {\bigodot} = \text {695,700 km} R. c. VOLUME = The Right Ascension (Longitude) is expressed in time (hh:mm:ss) and is how far along Earth's celestial equator the star is. Tt, T_, TT, a or b, b or c. June 13, 2021 by Leave a Comment by Leave a Comment Sirius is 25.4 times more luminous than our Sun. [89] It is calculated that SiriusA will have completely exhausted the store of hydrogen at its core within a billion (109)years of its formation, and will then evolve away from the main sequence. [146] The name of the North American satellite radio company CD Radio was changed to Sirius Satellite Radio in November 1999, being named after "the brightest star in the night sky". The luminosity of a star depends on its surface temperature and its diameter. In this, the arrow tip is pointed at the wolf Sirius. If you live in the Northern Hemisphere at a temperate latitude, Sirius is the very bright white star due south every winter in the evening. R = 695,700 km. Capella A Luminosity: 80 x Sun Capella B Luminosity: 75 x Sun. Many nations among the indigenous peoples of North America also associated Sirius with canines; the Seri and Tohono Oodham of the southwest note the star as a dog that follows mountain sheep, while the Blackfoot called it "Dog-face". [41], In his 1698 book, Cosmotheoros, Christiaan Huygens estimated the distance to Sirius at 27,664times the distance from the Earth to the Sun (about 0.437light-year, translating to a parallax of roughly 7.5arcseconds). The radius of Sirius B is 0.008 times bigger than the Sun. By modeling the evolution of a star with Sirius A's mass, the astronomers find the star achieves its current luminosity and diameter 225 to 250 million years after birth. Then get back to hunting Sirius B. This name is widely used on medieval astrolabes from Western Europe. There's no register feature and no need to give an email address if you don't want to. Below is a tabular view of the star facts with the values of the Sun on the right so you can compare them against our star, the Sun. If you give an email address, you may receive an email notifying you when someone else has added a comment to the same page. [107] The Greek word itself may have been imported from elsewhere before the Archaic period,[108] one authority suggesting a link with the Egyptian god Osiris. (roughly the distance between the Sun and Uranus) and a period of 50.1years. sirius b luminosity in comparison to sun. In that year, Sirius will come to within 1.6 degrees of the south celestial pole. C pH9 Over the years, its midnight culmination moves slowly, owing to the combination of the star's proper motion and the precession of the equinoxes. [11], In a letter dated 10August 1844, the German astronomer Friedrich Wilhelm Bessel deduced from changes in the proper motion of Sirius that it had an unseen companion. Now, its the dead remnant of a formerly active star. [65][66], In 1985, German astronomers Wolfhard Schlosser and Werner Bergmann published an account of an 8th-century Lombardic manuscript, which contains De cursu stellarum ratio by St.Gregory of Tours. Orion's Dog they call it, brightest In extreme cases, a foaming dog might have rabies, which could infect and kill humans they had bitten. [113][114] The star is referred to as Makarajyoti in Malayalam and has religious significance to the pilgrim center Sabarimala. The star generates more energy than our star. More like 0.6 to 0.8 times the Sun's mass. Luminosity is the amount of energy a star pumps out relative to the amount that our star, the Sun, gives out. Step-by-step solution. It is a binary star in the constellation Canis Major. An apparent "third star" observed in the 1920s is now believed to be a background object. Sirius, Alpha Canis Majoris ( CMa), is the brightest star in the night sky and one of the nearest star systems to Earth. [60] Thomas J.J. See resurrected discussion on red Sirius with the publication of several papers in 1892, and a final summary in 1926. The life span of stars ranges from about 10 million years for the At a distance of 2.64 parsecs (8.6ly), the Sirius system is one of Earth's nearest neighbours. Sirius rises late in the dark, liquid sky a. SLOPE = [92] It will pass through a red giant stage and eventually become a white dwarf. In fact, Sirius B is slightly smaller than the Earth, whose radius is 6400 km. Sirius B apparent magnitude is 8.44, which is a measure of the star's brightness as seen from Earth. This ruled out any objects orbiting SiriusA with more than 0.033solar mass (35Jupiter masses) orbiting in 0.5years, and 0.014 (15 Jupiter masses) in 2years. The midnight culmination of Sirius in the northern hemisphere coincides with the beginning of the New Year[130] of the Gregorian Calendar during the decades around the year 2000. A similar association is depicted at the Temple of Hathor in Dendera, where the goddess Satet has drawn her arrow at Hathor (Sirius). Select Luminosity on the Arranged by menu. In Iranian mythology, especially in Persian mythology and in Zoroastrianism, the ancient religion of Persia, Sirius appears as Tishtrya and is revered as the rain-maker divinity (Tishtar of New Persian poetry). Sirius B does not have twice the Sun's mass, or it would be a neutron star. Known as "Tir", the star was portrayed as the arrow itself in later Persian culture. . Bottom line: The skys brightest star Sirius is a double star. [42] There were several unsuccessful attempts to measure the parallax of Sirius: by Jacques Cassini (6seconds); by some astronomers (including Nevil Maskelyne)[43] using Lacaille's observations made at the Cape of Good Hope (4seconds); by Piazzi (the same amount); using Lacaille's observations made at Paris, more numerous and certain than those made at the Cape (no sensible parallax); by Bessel (no sensible parallax).[44]. Clmentine Fak-Nzuji Madiya, Canadian Museum of Civilization, Canadian Centre for Folk Culture Studies, International Centre for African Language, Literature and Tradition (Louvain, Belgium). This is due to precession and proper motion of Sirius itself which moves slowly in the SSW direction. Which of these nearby stars is the more typical of the stars in the Galactic disk in the power they generate? Sirius has a luminosity 25.4 times greater than the sun , but, because it is 8.6 light years away, its apparent brightness is 12 billion times less than that of the sun. American Museum of Natural History. Betelgeuse = 1800 Rsun Sirius = 1.7 Rsun Sun = 1 Rsun, by definition Companion of Sirius = 0.007 Rsun The largest known star has a radius 3700 times that of the Sun. The numbers given for Luminosity, Radius, and Mass are in comparison to the Sun. In theory, Sirius B should be just outside the bundle of shimmering brightness centered on Sirius A, but being pretty weak its hidden by the tremendous glare from the primary. A faint star will have a high number. ' Sirius A's luminosity figure of 25.4 is based on the value in the Simbad Hipparcos Extended Catalogue at the University of Strasbourg from 2012. [118], Many cultures have historically attached special significance to Sirius, particularly in relation to dogs. [76], The orbital motion of the Sirius binary system brings the two stars to a minimum angular separation of 3arcseconds and a maximum of 11arcseconds. Summary of the content and survey properties", "The Abundance Patterns of Sirius and Vega", "LXXVIII. One nominal solar luminosityis defined by the International Astronomical Unionto be 3.8281026 W.[2] [71] In Geoffrey Chaucer's essay Treatise on the Astrolabe, it bears the name Alhabor and is depicted by a hound's head. The uncertainty range for the effective temperature is between -24750 and +25250. To the naked eye, it often appears to be flashing with red, white, and blue hues when near the horizon. This star is primarily composed of a carbonoxygen mixture that was generated by helium fusion in the progenitor star. Our Sun is 864,000 miles in diameter and 10,000 degrees Fahrenheit on the surface. Sirius B radius has been calculated as being 0.008 times bigger than the Sun. It has an apparent magnitude of -1.46 and lies at a distance of only 8.6 light years from the Sun. [51] Observations published in 2008 were unable to detect either a third star or a planet. Basically, Sirius B is the white-hot dead body of a formerly large and very active star. bella vista catholic charities housing; wills point tx funeral homes; ptvi triathlon distance; is frankie beverly in the hospital; birria tacos long branch; The 1st-century poet Marcus Manilius described it as "sea-blue", as did the 4th-century Avienius. The separation between Rigel A and B is similar to the separation between Sirius A and B. As Mrgavyadha, the star represents Rudra (Shiva). The Ursa Major Group is a set of 220stars that share a common motion through space. According to the Hipparcos Catalogue, the star is an estimated 228 million years old but could be as young as 218 to 238. Sirius B's solar mass is 1.018 times that of our star, the Sun. Sirius B is currently close to due east from A (east-northeast), so it should be trailing the primary star, following the primary a little bit off to the side of As trajectory. [63], With an apparent magnitude of 1.46, Sirius is the brightest star in the night sky, almost twice as bright as the second-brightest star, Canopus. Surface temperature: 9,940 kelvins (K . After a periastron occurred in 1994,[c] [64] It was the standard white star in ancient China, and multiple records from the 2ndcentury BC up to the 7thcentury AD all describe Sirius as white. The initially more massive of these, SiriusB, consumed its hydrogen fuel and became a red giant before shedding its outer layers and collapsing into its current state as a white dwarf around 120million years ago.[13]. Sirius, also called Alpha Canis Majoris or the Dog Star, brightest star in the night sky, with apparent visual magnitude 1.46. It is also known as the Dog Star, in reference to its position as the luminary of the constellation Canis Major . sirius b luminosity in comparison to sun Luminosity is the amount of energy that a star pumps out and its relative to the amount that our star, the Sun gives out. Read about thermal issues at here and here. When stars are plotted on a luminosity vs surface temperature diagram (HR diagram), several interesting patterns emerge: Most stars fall on the Main Sequence. [125], Several cultures also associated the star with a bow and arrows. The Sun is a as a G2V type star, a yellow dwarf and a main sequence star. Schools Observatory. Scottish astronomer Thomas Henderson used his observations made in 18321833 and South African astronomer Thomas Maclear's observations made in 18361837, to determine that the value of the parallax was 0.23arcsecond, and error of the parallax was estimated not to exceed a quarter of a second, or as Henderson wrote in 1839, "On the whole we may conclude that the parallax of Sirius is not greater than half a second in space; and that it is probably much less. smaller, hotter, and less luminous . Typically, the brightest star in the constellation is classified as Alpha. You should not use less than half the magnifications indicated above: In other words, for a 200mm (8-inch) scope, stay between 200x and 400x. The cluster is over a thousand times further away from us than the star system, but given its size it still appears at magnitude 8.3. The bright component of the binary is a blue-white star 25.4 times as luminous as the Sun. A typical white dwarf has a mass equal to 0.5-0.6 solar masses. Star in the constellation Canis Major and brightest star in the night sky, Several terms redirect here. CONCLUSIONS For Sirius B, the location is 06h 45m 09.0 and -16 43` 06 . [73] Because of its declination of roughly 17, Sirius is a circumpolar star from latitudes south of 73S. From the Southern Hemisphere in early July, Sirius can be seen in both the evening where it sets after the Sun and in the morning where it rises before the Sun. If the Q-tip makes a puddle of alcohol on the lens that persists for a long time, youre using too much liquid. [81][84] The Chandra X-ray Observatory image shows SiriusB outshining its partner as an X-ray source. [59] The existence of other stars changing in brightness gave credibility to the idea that some may change in colour too; Sir John Herschel noted this in 1839, possibly influenced by witnessing Eta Carinae two years earlier. Its small stature has earned it the nickname "The Pup." Be very gentle. If youre an experienced astronomer, you can probably skip some of the following recommendations, as they are probably a matter of your daily routine. "[137] According to Noah Brosch cultural transfer of relatively modern astronomical information could have taken place in 1893, when a French expedition arrived in Central West Africa to observe the total eclipse on 16 April. Even in good seeing, itll wink in and out of existence. To compare different stars' actual brightness, you would best use Absolute rather than Apparent Magnitude. [71] From Earth, Sirius always appears dimmer than Jupiter and Venus, and at certain times also dimmer than Mercury and Mars. And fevers to suffering humanity. [70] Alternative explanations are either that the description as red is a poetic metaphor for ill fortune, or that the dramatic scintillations of the star when rising left the viewer with the impression that it was red. Canis Major was classically depicted as Orion's dog. Just relax and keep watching. On the other hand, the distance D to Sirius B is 8.2 - 31.5 times that of the Earth's distance from the Sun. What is Sirius B's luminosity compared to the sun Get the answers you need, now! Not so fast. Sirius B is a companion star to the brighter star Sirius which is the brightest star in the night sky. The eye-facing lens of any eyepiece is contaminated by grease from eyelashes within seconds of starting an observation. Sirius B is about as massive as the sun, but very small, about the same volume as the Earth. [b], The ancient Greeks observed that the appearance of Sirius as the morning star heralded the hot and dry summer and feared that the star caused plants to wilt, men to weaken, and women to become aroused. (3) Stars have a wide range of radii. The two stars revolve around each other every 50 years. Before that, take a look to the west (to the right) of Sirius, and observe the large constellation of Orion. [30] Owing to its brightness, Sirius would have been seen to twinkle more in the unsettled weather conditions of early summer. White dwarfs are the leftover remnants of stars similar to the sun. Only objects with a magnitude of 6.5 or less can be seen on a clear night. the Dog Star) Luminosity: 25.4 times greater than the Sun. [78], At a distance of 2.6parsecs (8.6ly), the Sirius system contains two of the eight nearest stars to the Sun, and it is the fifth closest stellar system to the Sun. To its right (west), you can see the great constellation of Orion, with bright red Betelgeuse near the top, then the Belt of three stars, then white Rigel at the base. Sometimes the eye is covered in excess fluid (tears, basically) which blurs the image. [143] The Royal Australian Navy subsequently named a vessel HMASSirius in honor of the flagship. [31] The season following the star's reappearance came to be known as the "dog days". With a mass of 1.02M, it is almost double the 0.50.6M average. The bright stars Aldebaran, Arcturus and Sirius were noted to have moved significantly; Sirius had progressed about 30 arcminutes (about the diameter of the Moon) to the southwest. Sirius B is a binary or multiple star system. The original star had an estimated 5M[13] and was a B-type star (most likely B5V for 5M)[96][97] when it was still on the main sequence, potentially burning around 600-1200 times more luminous than the sun. Radius: 1.71 times greater than the Sun. [90] A weak magnetic field has been detected on the surface of SiriusA. As a result, Sirius B is over 10,000 times dimmer than Sirius A and is even smaller than our Earth. If you want to see the comparison between Sirius B and our star, the Sun, you will need a screen of at least 800px across. [15] meaning iron is 316% as abundant as in the Sun's atmosphere. It is predictable to some extent. telescope. The White Dwarf would most probably have been a star much like our own, the Sun before it had come to the end of its life having used up all its fuel. Sirius B is south of the Ecliptic. Sirius B R = 0.033.9! Based on the star's spectral type of DA2, Sirius B's colour and type is white white dwarf. The system is between 200 and 300million years old. At a distance of 10 parsecs the Sun would be a magnitude 4.83 star. The list below may not include all the stars, only those that are recorded on this site. Called Sirius B, it forms a binary system with Sirius A, the brightest-appearing star in the sky. . What star has the surface temperature of approximatly 9000 k and luminosity 1 to 20. You can do it. [13] It was originally composed of two bright bluish stars. At just 8.7 light years away, Sirius is the seventh closest star to Earth. A good 100mm (4-inch) scope or larger should split it in the upcoming years. Except the brightness difference between Rigel A and B is much less than the difference between Sirius A and B, which makes Rigel a much easier double to split. The numbers given for Luminosity,Radius, and Mass are in comparison to the Sun. If the value is positive, it is north of the celestial equator. Oops! [13] The closest large neighbouring star to Sirius is Procyon, 1.61 parsecs (5.24ly) away. It is around 25 times brighter than our Sun and has a mass 2.02 times that of the Sun. I", "Mass-luminosity relation of intermediate-mass stars", "Gaia Data Release 3. higher than expected level of infrared radiation, "Contributions to the Nearby Stars (NStars) Project: Spectroscopy of stars earlier than M0 within 40parsecs: The Northern Sample. Its hard to catch the perfect seeing required, so persistence is important. If you have cleaned the mirror in the last few months, then feel free to ignore this part. There are many techniques and tools for collimation. Astronomers express the brightness of stars in terms of stellar . Sirius itself has a mass two times that of the Sun and a diameter of 1.5 million miles (2.4 million kilometers). But if the forecast is bad, theres probably no point in trying. These stars have absolute visual magnitudes of 4.4 and 5.7, respectively. The Declination (Latitude) is how far north or south the object is compared to the celestial equator and is expressed in degrees. Sirius B is about as massive as the sun, but very small, about the same volume as the Earth. We use the symbol L Sun to denote the Sun's luminosity; hence, that of Sirius can be written as 25 L Sun. These observing conditions are more easily met in the Southern Hemisphere, owing to the southerly declination of Sirius. In case you're wondering, Sirius B is not located within the Solar System, and there is only one star in the Solar System, the Sun. The other two are the Hyades and the Pleiades, and each of these clusters consists of hundreds of stars. There is no relationship between colour and size. "[45] Astronomers adopted a value of 0.25arcsecond for much of the 19thcentury. Capella A Mass: 2.7 x Sun Capella B Mass: 2.5 x Sun. The star cannot be seen by the naked eye, you need a telescope to see it. Dont confuse it with a diffraction artifact from the primary. It has a mass of 2.063 0.023 M which is two times that of the Sun and a diameter of 1.5 million miles8.611 light years from earth. It is a little more than two times the size of the Sun, which makes Sirius the brightest star in the night sky because of its proximity to our system. Sirius B is often lost in Sirius As tremendous glare, so you have to take special measures to make B visible. The temperature of each spectral class is then further subdivided from hot to cool by the simple addition of a number, where 0 is the hottest and 9 the coolest. kennedy461734 kennedy461734 12/08/2020 Biology High School answered What is Sirius B's luminosity compared to the sun 1 See answer Advertisement Luminosity is the intrinsic or actual amount of light given off by an object. We have step-by-step solutions for your textbooks written by Bartleby experts! Density = 1.015E-8 The temperature of the Sun is approximately 5800 K and the temperature of the star Sirius A, the larger star of the Sirius binary, is approximately 10,000 K. The luminosity of Sirius A is about 23 times that of the Sun. The Romans knew these days as dies caniculares, and the star Sirius was called Canicula, "little dog". It is important that the star is not too low in the sky, as seeing (turbulence) becomes much worse close to the horizon, and seeing is absolutely crucial for this observation. The 1st of March, the best time is 8 p.m. Come April 1st, Sirius already begins to descend after sunset, so the best observational season is coming to an end. [39][40] Compared to the modern value of 5.5km/s, this was an overestimate and had the wrong sign; the minus sign () means that it is approaching the Sun. The location of the Sirius B in the night sky is determined by the right ascension (R.A.) and declination (Dec.). Use your sense of touch to detect when you hit a dust mote lodged on the surface and avoid dragging it across. [13] This is overlaid by an envelope of lighter elements, with the materials segregated by mass because of the high surface gravity. Point the scope at Sirius, turn off tracking (if your scope has it), and let the star drift across the field. Procyon is almost seven times brighter than our sun, having 6.93 solar luminosities. By the time he died, he had calculated that one star orbited the other star in 50 years. Based on the location of Canis Major, Sirius B can be located in the southern hemisphere of the celestial sky. Sirius B, however, is an entirely different body. Keep looking at the primary star and be mindful of the surrounding area trailing the star as it drifts across the field. [25], Sirius appears bright because of its intrinsic luminosity and its proximity to the Solar System. [98] The outer atmosphere of SiriusB is now almost pure hydrogenthe element with the lowest massand no other elements are seen in its spectrum. Forget what youve heard on forums or from word-of-mouth about magnification limits; just plug in a strong eyepiece. Luminosity: 0.056 . If you cant see Rigel B, either seeing is so bad or your scope is so out of whack that theres no point to even try to see Sirius B. All agree, however, that they learned about the star from Griaule. {\displaystyle \textstyle \ \left[{\frac {{\ce {Fe}}}{{\ce {H}}}}\right]=0.5\ ,} Sirius, popularly known as "the Dog Star", is a V magnitude -1.46 star located in the constellation of Canis Major. [148], Composer Karlheinz Stockhausen, who wrote a piece called Sirius, is claimed to have said on several occasions that he came from a planet in the Sirius system. The luminosity of Sirius A can be found in The Brightest Twenty Stars, and is given as about 23 times that of the Sun. Something went wrong while submitting the form. The temperature was found to be even higher than that of the Sun; Seeing (or air turbulence) blurs the image whenever youre attempting a high-resolution observation from Earth. There are closer stars to Earth, but they are Main Sequence Stars such as Rigil Kentaurus, our nearest Sun-like star. The distance between the two varies between 8.2 and 31.5astronomical units as they orbit every 50years. It is not part of the Canis Major constellation outline but is within the borders of the constellation. Because of the concept of the yazatas, powers which are "worthy of worship", Tishtrya is a divinity of rain and fertility and an antagonist of apaosha, the demon of drought. Collimation is crucial for any high-resolution observation. To deliver peak performance, a telescope must be at thermal equilibrium with the environment. to Sirius has such a low total luminosity is that it's tiny - even smaller than the Earth. [6] When compared to the Sun, the proportion of iron in the atmosphere of SiriusA relative to hydrogen is given by At the closest approach, it is an observational challenge to distinguish the white dwarf from its more luminous companion, requiring a telescope with at least 300mm (12in) aperture and excellent seeing conditions. [139][140], Sirius features on the coat of arms of Macquarie University, and is the name of its alumnae journal. It was discovered during a statistical analysis of Gaia data. T = 5778 K. From there is it sent via the Sun to the god of Earth (Sanat Kumara), and finally through the seven Masters of the Seven Rays to the human race.[131]. That very bright white star not too high in the sky is Sirius. H Universe Guide Asteroid Asteroid Facts Popular Asteroids Apollo Chiron Eros Groom Hygiea Icarus Ida Iris Juno Pallas Vesta Comets A Reexamination of the Membership, Activity, and Age of the Ursa Major Group", "Bulletin of the IAU Working Group on Star Names", "Sirius midnight culmination New Years Eve", "About Macquarie University Naming of the University", "Lockheed Sirius "Tingmissartoq", Charles A. Lindbergh", "Sirius Satellite Radio, Inc. Company Profile, Information, Business Description, History, Background Information on Sirius Satellite Radio, Inc", NASA Astronomy Picture of the Day: Sirius B in x-ray (6 October 2000), Celestial objects within 510 light-years, https://en.wikipedia.org/w/index.php?title=Sirius&oldid=1142479743, Astronomical objects known since antiquity, Stars named from the Ancient Greek language, Short description is different from Wikidata, Articles containing Ancient Greek (to 1453)-language text, Articles containing Ancient Egyptian-language text, Creative Commons Attribution-ShareAlike License 3.0, This page was last edited on 2 March 2023, at 16:47. The Sun is our nearest star, which keeps us warm and gives us light as we complete one orbit in 365.24 days. A white dwarf forms after a star has evolved from the main sequence and then passed through a red giant stage. According to Marcel Griaule, they knew about the fifty-year orbital period of Sirius and its companion prior to western astronomers. It was once a member of an open cluster, but has since become gravitationally unbound from the cluster. If an exoplanet has been spotted or confirmed, it will probably be recorded in the Exoplanet EU database. Temperature is given using the Kelvin scale, where 273.15 K = 0 C and 373.15 K = 100 C. 106 m Compared to the radius of the Sun at 6.960 x 108 m, Sirius A is twice as large Sirius B is a hundred times smaller! Sirius A Luminosity Luminosity is the amount of energy a star pumps out relative to the amount that our star, the Sun, gives out. 1026 4" 5.67 ! The companion B star has an apparent visual magnitude of 1.3. Blog-Footer, Month Selector Blog-Footer, Month Selector . If your telescope is an open reflector (such as a Dobsonian), dust accumulating on the primary mirror will increase light scattering. [120][121][122][123], In Chinese astronomy Sirius is known as the star of the "celestial wolf" (Chinese and Japanese: Chinese romanization: Tinlng; Japanese romanization: Tenr;[124] Korean and romanization: /Tsnrang) in the Mansion of Jng (). = Sirius B's effective temperature is 25,000 Kelvin which is hotter than our own Sun's effective temperature, which is 5,777 Kelvin. Comparison of Sirius A and the Sun, to scale and relative surface brightness. Example: Sun: b = 1370 watts / meter 2. d = 1 AU = 1.5 x 10 11 meters (150 billion meters) L = 4 pi d 2 b = 3.9 x 10 26 watts (390 trillion trillion watts)