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79-469: 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 somewhere between 55,000 and 196,000 times that of the Sun . Its Bayer designation is α Cygni , which is Latinised to Alpha Cygni , abbreviated to Alpha Cyg or α Cyg . At a distance of 802 parsecs , it is the farthest star from Earth with

158-598: A B-V color index of −0.06. It contrasts strongly with reddish Betelgeuse. Culminating every year at midnight on 12 December, and at 9:00   pm on 24 January, Rigel is visible on winter evenings in the Northern Hemisphere and on summer evenings in the Southern Hemisphere . In the Southern Hemisphere, Rigel is the first bright star of Orion visible as the constellation rises. Correspondingly, it

237-408: A P Cygni profile after a star that shows this feature strongly in its spectrum. It is associated with mass loss where there is simultaneously emission from a dense wind close to the star and absorption from circumstellar material expanding away from the star. The unusual Hα line profile is observed to vary unpredictably. It is a normal absorption line around a third of the time. About a quarter of

316-401: A margin of error of about 9%. Rigel B, usually considered to be physically associated with Rigel and at the same distance, has a Gaia Data Release 3 parallax of 3.2352 ± 0.0553 mas , suggesting a distance around 1,000 light-years (310 parsecs). However, the measurements for this object may be unreliable. Indirect distance estimation methods have also been employed. For example, Rigel

395-446: A parallax using measurements from the astrometric satellite Hipparcos gave an uncertain result of 1.01 ± 0.57 mas that was consistent with this distance. However, the 2007 re-analysis gives a much larger parallax whose distance is barely half the current accepted value. This would result in a distance of 437 ± 61 pc , or 1424 ± 199 ly . The controversy over whether the direct Hipparcos measurements can be ignored in favour of

474-412: A binary system, and in 1878, he resolved it into two components. This visual companion is designated as component C (Rigel C), with a measured separation from component B that varies from less than 0.1″ to around 0.3″ . In 2009, speckle interferometry showed the two almost identical components separated by 0.124″ , with visual magnitudes of 7.5 and 7.6, respectively. Their estimated orbital period

553-449: A challenging target for telescope apertures smaller than 15 cm (6 in). At Rigel's estimated distance, Rigel B's projected separation from Rigel A is over 2,200   astronomical units (AU). Since its discovery, there has been no sign of orbital motion, although both stars share a similar common proper motion . The pair would have an estimated orbital period of 24,000   years. Gaia Data Release 2   (DR2) contains

632-591: A cutlass by the maiden Bįhi (Sirius). The Lacandon people of southern Mexico knew it as tunsel ("little woodpecker"). Rigel was known as Yerrerdet-kurrk to the Wotjobaluk koori of southeastern Australia, and held to be the mother-in-law of Totyerguil ( Altair ). The distance between them signified the taboo preventing a man from approaching his mother-in-law. The indigenous Boorong people of northwestern Victoria named Rigel as Collowgullouric Warepil . The Wardaman people of northern Australia know Rigel as

711-686: A daughter of Rehua ( Antares ), the chief of all-stars. Its heliacal rising presages the appearance of Matariki (the Pleiades ) in the dawn sky, marking the Māori New Year in late May or early June. The Moriori people of the Chatham Islands , as well as some Maori groups in New Zealand, mark the start of their New Year with Rigel rather than the Pleiades. Puaka is a southern name variant used in

790-567: A diameter about 200 times that of the Sun ; if placed at the center of the Solar System , Deneb would extend to the orbit of the Earth . It is one of the largest white 'A' spectral type stars known . Deneb is a bluish-white star of spectral type A2Ia, classifying it as a blue supergiant star with a surface temperature of 8,500 kelvin . Since 1943, its spectrum has served as one of the stable references by which other stars are classified. Its mass

869-494: A diameter of 25 million miles, or approximately 28.9  R ☉ , smaller than its neighbor Aldebaran . Due to their closeness to each other and ambiguity of the spectrum, little is known about the intrinsic properties of the members of the Rigel BC triple system. All three stars seem to be near equally hot B-type main-sequence stars that are three to four times as massive as the Sun. Stellar evolution models suggest

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948-515: A few hours to several days, but again no clear period. Rigel's color index varies slightly, but this is not significantly correlated with its brightness variations. From analysis of Hipparcos satellite photometry, Rigel is identified as belonging to the Alpha Cygni class of variable stars, defined as "non-radially pulsating supergiants of the Bep–AepIa spectral types". In those spectral types,

1027-536: A fifth component of the Rigel system. William Herschel discovered Rigel to be a visual double star on 1 October 1781, cataloguing it as star 33 in the "second class of double stars" in his Catalogue of Double Stars, usually abbreviated to H   II   33, or as H   2   33 in the Washington Double Star Catalogue. Friedrich Georg Wilhelm von Struve first measured the relative position of

1106-400: A luminosity of 55,000  L ☉ . Deneb is the most luminous first magnitude star, that is, stars with a brighter apparent magnitude than 1.5. Deneb is also the most distant of the 30 brightest stars by a factor of almost 2. Based on its temperature and luminosity, and also on direct measurements of its tiny angular diameter (a mere 0.002 seconds of arc), Deneb appears to have

1185-476: A magnitude higher than 2.50. α Cygni (Latinised to Alpha Cygni ) is the star's designation given by Johann Bayer in 1603. The traditional name Deneb is derived from the Arabic word for "tail", from the phrase ذنب الدجاجة Dhanab al-Dajājah , or "tail of the hen". The IAU Working Group on Star Names has recognised the name Deneb for this star, and it is entered in their Catalog of Star Names. Denebadigege

1264-782: A mass of 24 ± 8   M ☉ . Although Rigel is often considered the most luminous star within 1,000 light-years of the Sun, its energy output is poorly known. Using the Hipparcos distance of 860 light-years (264 parsecs), the estimated relative luminosity for Rigel is about 120,000 times that of the Sun ( L ☉ ), but another recently published distance of 1,170 ± 130 light-years (360 ± 40 parsecs) suggests an even higher luminosity of 219,000  L ☉ . Other calculations based on theoretical stellar evolutionary models of Rigel's atmosphere give luminosities anywhere between 83,000  L ☉ and 363,000  L ☉ , while summing

1343-499: A neutron star. The earliest known recording of the name Rigel is in the Alfonsine tables of 1521. It is derived from the Arabic name Rijl Jauzah al Yusrā , "the left leg (foot) of Jauzah" (i.e. rijl meaning "leg, foot"), which can be traced to the 10th century. "Jauzah" was a proper name for Orion; an alternative Arabic name was رجل الجبار rijl al-jabbār , "the foot of

1422-457: A period of about 22 days. The radial velocity has since been measured to vary by about 10  km/s around a mean of 21.5 km/s . In 1933, the Hα line in Rigel's spectrum was seen to be unusually weak and shifted 0.1  nm towards shorter wavelengths, while there was a narrow emission spike about 1.5 nm to the long wavelength side of the main absorption line. This is now known as

1501-472: A period of about 850 days, where the spectral lines from the star suggest cyclical radial velocity changes. Later investigations have found no evidence supporting the existence of a companion. Names similar to Deneb have been given to at least seven different stars, most notably Deneb Kaitos , the brightest star in the constellation of Cetus ; Deneb Algedi , the brightest star in Capricornus ; and Denebola ,

1580-509: A possible period of 2.075 days. Rigel was observed with the Canadian MOST satellite for nearly 28 days in 2009. Milli-magnitude variations were observed, and gradual changes in flux suggest the presence of long-period pulsation modes. From observations of the variable Hα spectral line, Rigel's mass-loss rate due to stellar wind is estimated be (1.5 ± 0.4) × 10 solar masses per year ( M ☉ /yr)—about ten million times more than

1659-508: A rapidly rotating star during its main sequence phase. Deneb is the prototype of the Alpha Cygni (α Cygni) variable stars , whose small irregular amplitudes and rapid pulsations can cause its magnitude to vary anywhere between 1.21 and 1.29. Its variable velocity discovered by Lee in 1910, but it was not formally placed as a unique class of variable stars until the 1985 4th edition of the General Catalogue of Variable Stars. The cause of

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1738-540: A somewhat unreliable parallax for Rigel B, placing it at about 1,100 light-years (340 parsecs), further away than the Hipparcos distance for Rigel, but similar to the Taurus-Orion R1 association. There is no parallax for Rigel in Gaia DR2. The Gaia DR2 proper motions for Rigel B and the Hipparcos proper motions for Rigel are both small, although not quite the same. In 1871, Sherburne Wesley Burnham suspected Rigel B to be

1817-406: A star of 24 ± 3  M ☉ seven to nine million years ago. Rigel's distance from the Sun is somewhat uncertain, different estimates being obtained by different methods. Old estimates placed it 166 parsecs (or 541 light years) away from the Sun. The 2007 Hipparcos new reduction of Rigel's parallax is 3.78 ± 0.34  mas , giving a distance of 863 light-years (265 parsecs) with

1896-445: 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. Rigel varies slightly in brightness, its apparent magnitude ranging from 0.05 to 0.18. It is classified as an Alpha Cygni variable due to the amplitude and periodicity of its brightness variation, as well as its spectral type. Its intrinsic variability

1975-423: A supergiant. Stars in the mass range of Deneb eventually expand to become the most luminous red supergiants , and within a few million years their cores will collapse producing a supernova explosion. It is now known that red supergiants up to a certain mass explode as the commonly seen type II-P supernovae , but more massive ones lose their outer layers to become hotter again. Depending on their initial masses and

2054-687: A typical member. Due to the Earth's axial precession , Deneb will be an approximate pole star (7° off of the north celestial pole) at around 9800 AD . The north pole of Mars points to the midpoint of the line connecting Deneb and the star Alderamin . Deneb's adopted distance from the Earth is around 802 parsecs (2,620 ly). This is based on the distance to the Cygnus OB7 association. Another distance estimate using its bolometric magnitude implied by its effective temperature and surface gravity gives 762 parsecs (2,490 ly). The original derivation of

2133-441: A wide range of indirect stellar models and interstellar distance scales is similar to the better known situation with the Pleiades . Deneb's absolute magnitude is estimated as −8.4, placing it among the visually brightest stars known, with an estimated luminosity of nearly 200,000  L ☉ . This is towards the upper end of values published over the past few decades. By the distance from Hipparcos parallax, Deneb has

2212-433: Is Arided / ˈ ær ɪ d ɛ d / , from the Arabic ar-ridf 'the one sitting behind the rider' (or just 'the follower'), perhaps referring to the other major stars of Cygnus, which were called al-fawāris 'the riders'. The 19th brightest star in the night sky, Deneb culminates each year on October 23 at 6 PM and September 7 at 9 PM, corresponding to summer evenings in the northern hemisphere . It never dips below

2291-633: Is 天津四 ( Tiān Jīn sì , English: the Fourth Star of the Celestial Ford ). In the Chinese love story of Qi Xi , Deneb marks the magpie bridge across the Milky Way , which allows the separated lovers Niu Lang ( Altair ) and Zhi Nü ( Vega ) to be reunited on one special night of the year in late summer. In other versions of the story, Deneb is a fairy who acts as chaperone when the lovers meet. USS Arided

2370-416: Is 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

2449-602: Is 63   years. Burnham listed the Rigel multiple system as β   555 in his double star catalog or BU   555 in modern use. Component B is a double-lined spectroscopic binary system, which shows two sets of spectral lines combined within its single stellar spectrum . Periodic changes observed in relative positions of these lines indicate an orbital period of 9.86   days. The two spectroscopic components Rigel Ba and Rigel Bb cannot be resolved in optical telescopes but are known to both be hot stars of spectral type around B9. This spectroscopic binary, together with

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2528-426: Is a runaway star with a complex history and might have originally formed in the main body of the association. Hierarchical scheme for Rigel's components The star system of which Rigel is a part has at least four components. Rigel (sometimes called Rigel A to distinguish from the other components) has a visual companion , which is likely a close triple-star system. A fainter star at a wider separation might be

2607-417: Is a defining point of the classification sequence for supergiants. The overall spectrum is typical for a late B class star, with strong absorption lines of the hydrogen Balmer series as well as neutral helium lines and some of heavier elements such as oxygen, calcium, and magnesium. The luminosity class for B8 stars is estimated from the strength and narrowness of the hydrogen spectral lines, and Rigel

2686-633: Is almost always brighter than α Orionis ( Betelgeuse ). Astronomer J.B. Kaler speculated that Bayer assigned letters during a rare period when variable star Betelgeuse temporarily outshone Rigel, resulting in Betelgeuse being designated "alpha" and Rigel designated "beta". However, closer examination of Bayer's method shows that he did not strictly order the stars by brightness, but instead grouped them first by magnitude, then by declination . Rigel and Betelgeuse were both classed as first magnitude , and in Orion

2765-479: Is also the first star of Orion to set in most of the Northern Hemisphere. The star is a vertex of the " Winter Hexagon ", an asterism that includes Aldebaran , Capella , Pollux , Procyon , and Sirius . Rigel is a prominent equatorial navigation star , being easily located and readily visible in all the world's oceans (the exception is the area north of the 82nd parallel north ). Rigel's spectral type

2844-549: Is an outlying member of the Orion OB1 association , which is located at a distance of up to 1,600 light-years (500 parsecs) from Earth. It is a member of the loosely defined Taurus-Orion R1 Association , somewhat closer at 1,200 light-years (360 parsecs). Rigel is thought to be considerably closer than most of the members of Orion OB1 and the Orion Nebula . Betelgeuse and Saiph lie at a similar distance to Rigel, although Betelgeuse

2923-464: Is assigned to the bright supergiant class Ia. Variations in the spectrum have resulted in the assignment of different classes to Rigel, such as B8 Ia, B8 Iab, and B8 Iae. As early as 1888, the heliocentric radial velocity of Rigel, as estimated from the Doppler shifts of its spectral lines, was seen to vary. This was confirmed and interpreted at the time as being due to a spectroscopic companion with

3002-446: Is believed to be in a region of nebulosity , its radiation illuminating several nearby clouds. Most notable of these is the 5°-long IC 2118 (Witch Head Nebula), located at an angular separation of 2.5° from the star, or a projected distance of 39 light-years (12 parsecs) away. From measures of other nebula-embedded stars, IC   2118's distance is estimated to be 949 ± 7 light-years (291 ± 2 parsecs). Rigel

3081-405: Is caused by stellar pulsations similar to those of Deneb . Further observations of radial velocity variations indicate that it simultaneously oscillates in at least 19 non-radial modes with periods ranging from about 1.2 to 74 days. Estimation of many physical characteristics of blue supergiant stars, including Rigel, is challenging due to their rarity and uncertainty about how far they are from

3160-413: Is caused by pulsations in its unstable atmosphere. Rigel is generally the seventh-brightest star in the night sky and the brightest star in Orion, though it is occasionally outshone by Betelgeuse , which varies over a larger range. A triple-star system is separated from Rigel by an angle of 9.5  arc seconds . It has an apparent magnitude of 6.7, making it 1/400th as bright as Rigel. Two stars in

3239-423: Is estimated at 19 M ☉ . Stellar winds causes matter to be lost at an average rate of 8±3 × 10  M ☉ per year, 100,000 times the Sun's rate of mass loss or equivalent to about one Earth mass per 500 years. Deneb spent much of its early life as an O-type main-sequence star of about 23  M ☉ , but it has now exhausted the hydrogen in its core and expanded to become

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3318-522: Is likely to be fusing helium in its core. Due to strong convection of helium produced in the core while Rigel was on the main sequence and in the hydrogen-burning shell since it became a supergiant, the fraction of helium at the surface has increased from 26.6% when the star formed to 32% now. The surface abundances of carbon, nitrogen, and oxygen seen in the spectrum are compatible with a post-red supergiant star only if its internal convection zones are modeled using non-homogeneous chemical conditions known as

3397-502: Is listed in the General Catalogue of Variable Stars , but since its familiar Bayer designation is used instead of creating a separate variable star designation . Rigel is an intrinsic variable star with an apparent magnitude ranging from 0.05 to 0.18. It is typically the seventh-brightest star in the celestial sphere , excluding the Sun, although occasionally fainter than Betelgeuse. Rigel appears slightly blue-white and has

3476-410: Is the approximate shape of a right triangle , with Deneb located at one of the acute angles. The spectrum of Alpha Cygni has been observed by astronomers since at least 1888, and by 1910 the variable radial velocity had become apparent. This led to the early suggestion by E. B. Frost that this is a binary star system. In 1935, the work of G. F. Paddock and others had established that this star

3555-399: 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 860 light-years (260  pc ) from the Sun. A star of spectral type B8Ia, Rigel is 120,000 times as luminous as the Sun, and

3634-467: The Ledoux Criteria . Rigel is expected to eventually end its stellar life as a type II supernova . It is one of the closest known potential supernova progenitors to Earth, and would be expected to have a maximum apparent magnitude of around −11 (about the same brightness as a quarter Moon or around 300 times brighter than Venus ever gets). The supernova would leave behind either a black hole or

3713-553: The spectral energy distribution from historical photometry with the Hipparcos distance suggests a luminosity as low as 61,515 ± 11,486  L ☉ . A 2018 study using the Navy Precision Optical Interferometer measured the angular diameter as 2.526 mas . After correcting for limb darkening , the angular diameter is found to be 2.606 ± 0.009 mas , yielding a radius of 74.1 +6.1 −7.3   R ☉ . An older measurement of

3792-445: The 'e' indicates that it displays emission lines in its spectrum, while the 'p' means it has an unspecified spectral peculiarity. Alpha Cygni type variables are generally considered to be irregular or have quasi-periods . Rigel was added to the General Catalogue of Variable Stars in the 74th name-list of variable stars on the basis of the Hipparcos photometry, which showed variations with a photographic amplitude of 0.039 magnitudes and

3871-461: The IAU describes such names as "useful nicknames" that are "unofficial". In modern comprehensive catalogs, the whole multiple star system is known as WDS 05145-0812 or CCDM 05145–0812. The designation of Rigel as β Orionis ( Latinized to beta Orionis ) was made by Johann Bayer in 1603. The "beta" designation is usually given to the second-brightest star in each constellation, but Rigel

3950-477: The Red Kangaroo Leader Unumburrgu and chief conductor of ceremonies in a songline when Orion is high in the sky. Eridanus , the river, marks a line of stars in the sky leading to it, and the other stars of Orion are his ceremonial tools and entourage. Betelgeuse is Ya-jungin "Owl Eyes Flicking", watching the ceremonies. The Māori people of New Zealand named Rigel as Puanga , said to be

4029-605: The South Island. In Japan, the Minamoto or Genji clan chose Rigel and its white color as its symbol, calling the star Genji-boshi ( 源氏星 ), while the Taira or Heike clan adopted Betelgeuse and its red color. The two powerful families fought the Genpei War ; the stars were seen as facing off against each other and kept apart only by the three stars of Orion's Belt . The MS Rigel

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4108-401: The Sun. As such, their characteristics are mainly estimated from theoretical stellar evolution models . Its effective temperature can be estimated from the spectral type and color to be around 12,100  K . A mass of 21 ± 3  M ☉ at an age of 8 ± 1   million years has been estimated by comparing evolutionary tracks, while atmospheric modeling from the spectrum gives

4187-436: The angular diameter gives 2.75 ± 0.01 mas , equivalent to a radius of 78.9  R ☉ at 264 pc . These radii are calculated assuming the Hipparcos distance of 264 pc ; adopting a distance of 360 pc leads to a significantly larger size. Older distance estimates were mostly far lower than modern estimates, leading to lower radius estimates; a 1922 estimate by John Stanley Plaskett gave Rigel

4266-436: The close visual component Rigel C, is likely a physical triple-star system, although Rigel C cannot be detected in the spectrum, which is inconsistent with its observed brightness. In 1878, Burnham found another possibly associated star of approximately 13th magnitude. He listed it as component D of β   555, although it is unclear whether it is physically related or a coincidental alignment. Its 2017 separation from Rigel

4345-401: The companion in 1822, cataloguing the visual pair as Σ 668. The secondary star is often referred to as Rigel B or β Orionis B. The angular separation of Rigel B from Rigel A is 9.5 arc seconds to its south along position angle 204°. Although not particularly faint at visual magnitude 6.7, the overall difference in brightness from Rigel A (about 6.6 magnitudes or 440 times fainter) makes it

4424-541: The constellation representing the mythological Greek huntsman Orion , Rigel is his knee or (as its name suggests) foot; with the nearby star Beta Eridani marking Orion's footstool. Rigel is presumably the star known as " Aurvandil 's toe" in Norse mythology . In the Caribbean, Rigel represented the severed leg of the folkloric figure Trois Rois , himself represented by the three stars of Orion's Belt. The leg had been severed with

4503-406: The first time are most likely fusing hydrogen in a shell around a helium core that has not yet grown hot enough to start fusion to carbon and oxygen . Convection has begun dredging up fusion products but these do not reach the surface. Post-red supergiant stars are expected to show those fusion products at the surface due to stronger convection during the red supergiant phase and due to loss of

4582-460: The great one", from which stems the rarely used variant names Algebar or Elgebar . The Alphonsine tables saw its name split into "Rigel" and "Algebar", with the note, et dicitur Algebar. Nominatur etiam Rigel. Alternate spellings from the 17th century include Regel by Italian astronomer Giovanni Battista Riccioli , Riglon by German astronomer Wilhelm Schickard , and Rigel Algeuze or Algibbar by English scholar Edmund Chilmead . With

4661-453: The horizon at or above 45° north latitude, just grazing the northern horizon at its lowest point at such locations as Minneapolis , Montréal and Turin . In the southern hemisphere , Deneb is not visible south of 45° parallel south , so it just barely rises above the horizon in South Africa , southern Australia , and northern New Zealand during the southern winter. Deneb is located at

4740-707: The inner pair every 63 years. A much fainter star, separated from Rigel and the others by nearly an arc minute , may be part of the same star system. In 2016, the International Astronomical Union (IAU) included the name "Rigel" in the IAU Catalog of Star Names. According to the IAU, this proper name applies only to the primary component A of the Rigel system. The system is listed variously in historical astronomical catalogs as H II 33, Σ 668, β 555, or ADS 3823. For simplicity, Rigel's companions are referred to as Rigel B, C, and D;

4819-488: The mass-loss rate from the Sun . More detailed optical and K   band infrared spectroscopic observations, together with VLTI interferometry, were taken from 2006 to 2010. Analysis of the Hα and Hγ line profiles, and measurement of the regions producing the lines, show that Rigel's stellar wind varies greatly in structure and strength. Loop and arm structures were also detected within

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4898-465: The obscuring outer layers of the star. Deneb is thought to be increasing its temperature after a period as a red supergiant, although current models do not exactly reproduce the surface elements showing in its spectrum. On the contrary, it is possible that Deneb has just left the main sequence and is evolving to a red supergiant phase, which is in agreement with estimates of its current mass, while its spectral composition can be explained by Deneb having been

4977-423: The pulsations of Alpha Cygni variable stars are not fully understood, but their irregular nature seems to be due to beating of multiple pulsation periods. Analysis of radial velocities determined 16 different harmonic pulsation modes with periods ranging between 6.9 and 100.8 days. A longer period of about 800 days probably also exists. Deneb has been reported as a possible single line spectroscopic binary with

5056-415: The pulsations of Rigel are powered by nuclear reactions in a hydrogen-burning shell that is at least partially non-convective. These pulsations are stronger and more numerous in stars that have evolved through a red supergiant phase and then increased in temperature to again become a blue supergiant. This is due to the decreased mass and increased levels of fusion products at the surface of the star. Rigel

5135-654: The quantity and velocity of material being expelled from the star. Occasional very high-velocity outflows have been inferred, and, more rarely, infalling material. The overall picture is one of large looping structures arising from the photosphere and driven by magnetic fields. Rigel has been known to vary in brightness since at least 1930. The small amplitude of Rigel's brightness variation requires photoelectric or CCD photometry to be reliably detected. This brightness variation has no obvious period. Observations over 18 nights in 1984 showed variations at red, blue, and yellow wavelengths of up to 0.13 magnitudes on timescales of

5214-454: The rate of mass loss, they may explode as yellow hypergiants or luminous blue variables , or they may become Wolf-Rayet stars before exploding in a type Ib or Ic supernova . Identifying whether Deneb is currently evolving towards a red supergiant or is currently evolving bluewards again would place valuable constraints on the classes of stars that explode as red supergiants and those that explode as hotter stars. Stars evolving red-wards for

5293-510: The second brightest star in Leo . All these stars are referring to the tail of the animals that their respective constellations represent. In Chinese, 天津 ( Tiān Jīn ), meaning Celestial Ford , refers to an asterism consisting of Deneb, Gamma Cygni , Delta Cygni , 30 Cygni , Nu Cygni , Tau Cygni , Upsilon Cygni , Zeta Cygni and Epsilon Cygni . Consequently, the Chinese name for Deneb itself

5372-586: The stars of each class appear to have been ordered north to south. Rigel has many other stellar designations taken from various catalogs, including the Flamsteed 19 Orionis (19 Ori), the Bright Star Catalogue entry HR 1713, and the Henry Draper Catalogue number HD 34085. These designations frequently appear in the scientific literature, but rarely in popular writing. Rigel

5451-408: The system can be seen by large telescopes, and the brighter of the two is a spectroscopic binary . These three stars are all blue-white main-sequence stars , each three to four times as massive as the Sun. Rigel and the triple system orbit a common center of gravity with a period estimated to be 24,000 years. The inner stars of the triple system orbit each other every 10 days, and the outer star orbits

5530-432: The time, it is a double-peaked line, that is, an absorption line with an emission core or an emission line with an absorption core. About a quarter of the time it has a P Cygni profile; most of the rest of the time, the line has an inverse P Cygni profile, where the emission component is on the short wavelength side of the line. Rarely, there is a pure emission Hα line. The line profile changes are interpreted as variations in

5609-612: The tip of the Northern Cross asterism made up of the brightest stars in Cygnus, the others being Albireo (Beta Cygni), Gamma Cygni , Delta Cygni , and Epsilon Cygni . It also lies at one vertex of the prominent and widely spaced asterism called the Summer Triangle , shared with the first- magnitude stars Vega in the constellation Lyra and Altair in Aquila . This outline of stars

5688-469: The wind. Calculations of mass loss from the Hγ line give (9.4 ± 0.9) × 10   M ☉ /yr in 2006-7 and (7.6 ± 1.1) × 10   M ☉ /yr in 2009–10. Calculations using the Hα line give lower results, around 1.5 × 10   M ☉ /yr . The terminal wind velocity is 300 km/s . It is estimated that Rigel has lost about three solar masses ( M ☉ ) since beginning life as

5767-405: Was 44.5 ″ , almost due north at a position angle of 1°. Gaia DR2 finds it to be a 12th magnitude sunlike star at approximately the same distance as Rigel. Likely a K-type main-sequence star , this star would have an orbital period of around 250,000 years, if it is part of the Rigel system. A spectroscopic companion to Rigel was reported on the basis of radial velocity variations, and its orbit

5846-486: Was variable in luminosity with a dominant period of 11.7 days and possibly with other, lower amplitude periods. By 1954, closer examination of the star's calcium H and K lines showed a stationary core, which indicated the variable velocity was instead being caused by motion of the star's atmosphere . This variation ranged from +6 to −9 km/s around the star's mean radial velocity. Other, similar supergiants were found to have variable velocities, with this star being

5925-454: Was a United States Navy Crater -class cargo ship named after the star. SS Deneb was an Italian merchant vessel that bore this name from 1951 until she was scrapped in 1966. Rigel Rigel is a blue supergiant star in the constellation of Orion . It has the Bayer designation β Orionis , which is Latinized to Beta Orionis and abbreviated Beta Ori or β Ori . Rigel

6004-556: Was even calculated, but subsequent work suggests the star does not exist and that observed pulsations are intrinsic to Rigel itself. Rigel is a blue supergiant that has exhausted the hydrogen fuel in its core, expanded and cooled as it moved away from the main sequence across the upper part of the Hertzsprung–Russell diagram . When it was on the main sequence, its effective temperature would have been around 30,000  K . Rigel's complex variability at visual wavelengths

6083-732: Was originally a Norwegian ship, built in Copenhagen in 1924. It was requisitioned by the Germans during World War II and sunk in 1944 while being used to transport prisoners of war. Two US Navy ships have borne the name USS Rigel . The SSM-N-6 Rigel was a cruise missile program for the US Navy that was cancelled in 1953 before reaching deployment. The Rigel Skerries are a chain of small islands in Antarctica , renamed after originally being called Utskjera. They were given their current name as Rigel

6162-470: Was used as an astrofix . Mount Rigel , elevation 1,910 m (6,270 ft), is also in Antarctica. Stellar atmosphere The stellar atmosphere is the outer region of the volume of a star , lying above the stellar core , radiation zone and convection zone . The stellar atmosphere is divided into several regions of distinct character: During a total solar eclipse , the photosphere of

6241-600: Was used in the Alfonsine Tables , other variants include Deneb Adige , Denebedigege and Arided . This latter name was derived from Al Ridhādh , a name for the constellation. Johann Bayer called it Arrioph , derived from Aridf and Al Ridf , 'the hindmost' or Gallina . German poet and author Philippus Caesius termed it Os rosae , or Rosemund in German, or Uropygium – the parson's nose. The names Arided and Aridif have fallen out of use. An older traditional name

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