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86-398: The Planetarium's 23-meter dome can seat four hundred spectators viewing projections of the sky from both analogue and digital planetarium projectors . It hosts regular public shows on astronomical topics as well as a variety of other events. In 2011 it hosted the fifth International Olympiad on Astronomy and Astrophysics . The Planetarium's sister astronomical observatory is equipped with

172-519: A star projector , is a device used to project images of celestial objects onto the dome in a planetarium . Modern planetarium projectors were first designed and built by the Carl Zeiss Jena company in Germany between 1923 and 1925, and have since grown more complex. Smaller projectors include a set of fixed stars, Sun, Moon, and planets, and various nebulae . Larger machines also include comets and

258-489: A "typical" planetarium projector of the 1960s was the Universal Projection Planetarium type 23/6, made by VEB Carl Zeiss Jena in what was then East Germany . This model of Zeiss projector was a 13-foot (4.0 m)-long dumbbell-shaped object, with 29-inch (740 mm)-diameter spheres attached at each end representing the night sky for the northern and southern hemispheres. Connecting the two spheres

344-504: A 300-mm diameter refracting telescope (the largest refractor in use in Poland) and a number of smaller instruments. On cloudless days, visitors can view live images of the Sun and, after dusk, a range of celestial objects at a magnification of up to 750 times. The observatory conducts research on comets and minor planets . The Planetarium has an astronomical library of some 10,000 volumes and, in

430-416: A B–V color index of 1.85 – a figure which points to its pronounced "redness". The photosphere has an extended atmosphere , which displays strong lines of emission rather than absorption , a phenomenon that occurs when a star is surrounded by a thick gaseous envelope (rather than ionized). This extended gaseous atmosphere has been observed moving toward and away from Betelgeuse, depending on fluctuations in

516-493: A blue tinge. An image of the Milky Way was created by using drum-type projectors that were studded with unfocused pinprick-sized holes based on photographic images of our galaxy. Specific projectors could imitate the light changes of such variable stars as Algol or Omicron Ceti , and other projectors could produce images of the constellations, of specific historical comets , compass points and other astronomical phenomena. When

602-436: A diameter of 0.047″ , although the stellar disk was likely 17% larger due to the limb darkening , resulting in an estimate for its angular diameter of about 0.055". Since then, other studies have produced angular diameters that range from 0.042 to 0.069″ . Combining these data with historical distance estimates of 180 to 815 ly yields a projected radius of the stellar disk of anywhere from 1.2 to 8.9 AU . Using

688-520: A diameter of 3.84 × 10  km ( 2.58  AU ) based on the parallax value of 0.018 ″ . But limb darkening and measurement errors resulted in uncertainty about the accuracy of these measurements. The 1950s and 1960s saw two developments that affected stellar convection theory in red supergiants: the Stratoscope projects and the 1958 publication of Structure and Evolution of the Stars , principally

774-543: A distance of roughly 131 pc or 427 ly , and had a smaller reported error than previous measurements. However, later evaluation of the Hipparcos parallax measurements for variable stars like Betelgeuse found that the uncertainty of these measurements had been underestimated. In 2007, an improved figure of 6.55 ± 0.83 was calculated, hence a much tighter error factor yielding a distance of roughly 152 ± 20 pc or 500 ± 65 ly . In 2008, measurements using

860-537: A dust cloud that blocked the starlight coming from about a quarter of Betelgeuse's surface. Hubble captured signs of dense, heated material moving through the star's atmosphere in September, October and November before several telescopes observed the more marked dimming in December and the first few months of 2020. By January 2020, Betelgeuse had dimmed by a factor of approximately 2.5 from magnitude 0.5 to 1.5 and

946-662: A far greater selection of stars. Additional projectors can be added to show twilight around the outside of the screen (complete with city or country scenes) as well as the Milky Way . Still others add coordinate lines and constellations , photographic slides, laser displays, and other images. The OMNIMAX movie system (now known as IMAX Dome) was originally designed to operate on planetarium screens. Companies that make (or have made) planetarium projectors include Carl Zeiss Jena (Germany), Spitz (US), Goto and Minolta (Japan), Evans & Sutherland (US), Emerald planetariums (Israel) and Ohira Tech (Japan). A good example of

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1032-519: A few hundred days are typically due to fundamental and first overtone pulsation. Lines in the spectrum of Betelgeuse show doppler shifts indicating radial velocity changes corresponding, very roughly, to the brightness changes. This demonstrates the nature of the pulsations in size, although corresponding temperature and spectral variations are not clearly seen. Variations in the diameter of Betelgeuse have also been measured directly. First overtone pulsations of 185 days have been observed, and

1118-582: A fully digital projection system, in which a single projector with a fish eye lens, or a system of digital video or laser video projectors around the edge of the dome, are used to create any scene provided to it from a computer. This gives the operator tremendous flexibility in showing not only the modern night sky as visible from Earth , but any other image they wish (including the sky as visible from points far distant in space and time). While many projection systems maintain their large single or multiple projectors, other systems cater to portable planetariums, like

1204-480: A little over twenty times that of the Sun . For various reasons , its distance has been quite difficult to measure; current best estimates are of the order of 400–600  light-years from the Sun ;– a comparatively wide uncertainty for a relatively nearby star. Its absolute magnitude is about −6. With an age of less than 10 million years, Betelgeuse has evolved rapidly because of its large mass, and

1290-548: A more normal brightness range, reaching a peak of 0.0 visual and 0.1 V-band magnitude in April 2023. Infrared observations found no significant change in luminosity over the last 50 years, suggesting that the dimming was due to a change in extinction around the star rather than a more fundamental change. A study using the Hubble Space Telescope suggests that occluding dust was created by a surface mass ejection; this material

1376-487: A particular star or planet dipped below the artificial horizon , a gravity-based mercury -filled shutter would be activated, blocking out the light. Since the release of the Evans & Sutherland Digistar in 1983, a single projector with a fish eye lens was able for the first time to show stars from points of view other than Earth's surface, travel through the stars, and accurately show celestial bodies from different times in

1462-540: A portrait of high resolution. It was this methodology that identified the hotspots on Betelgeuse in the 1990s. Other technological breakthroughs include adaptive optics , space observatories like Hipparcos, Hubble and Spitzer , and the Astronomical Multi-BEam Recombiner (AMBER) , which combines the beams of three telescopes simultaneously, allowing researchers to achieve milliarcsecond spatial resolution . Observations in different regions of

1548-502: A resolution superior to that obtained by ground-based interferometers—the first conventional-telescope image (or "direct-image" in NASA terminology) of the disk of another star. Because ultraviolet light is absorbed by the Earth's atmosphere , observations at these wavelengths are best performed by space telescopes . This image, like earlier pictures, contained a bright patch indicating a region in

1634-568: A table of the first two batches of names approved by the WGSN, which included Betelgeuse for this star. It is now so entered in the IAU Catalog of Star Names . Betelgeuse and its red coloration have been noted since antiquity ; the classical astronomer Ptolemy described its color as ὑπόκιρρος ( hypókirrhos = more or less orange-tawny), a term later described by a translator of Ulugh Beg 's Zij-i Sultani as rubedo , Latin for "ruddiness". In

1720-468: A third estimate in the near-infrared corroborating the 2009 numbers, this time showing a limb-darkened disk diameter of 42.49 ± 0.06 mas . The near-infrared photospheric diameter of 43.33 mas at the Hipparcos distance of 152 ± 20 pc equates to about 3.4 AU or 730  R ☉ . A 2014 paper derives an angular diameter of 42.28 mas (equivalent to a 41.01 mas uniform disc) using H and K band observations made with

1806-402: A trigonometric parallax of 5 ± 4 mas , a distance of 200 pc or 650 ly . Given this uncertainty, researchers were adopting a wide range of distance estimates, leading to significant variances in the calculation of the star's attributes. The results from the Hipparcos mission were released in 1997. The measured parallax of Betelgeuse was 7.63 ± 1.64 mas , which equated to

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1892-450: Is α Orionis , Latinised to Alpha Orionis and abbreviated Alpha Ori or α Ori . With a radius between 640 and 764 times that of the Sun, if it were at the center of our Solar System , its surface would lie beyond the asteroid belt and it would engulf the orbits of Mercury , Venus , Earth , and Mars . Calculations of Betelgeuse's mass range from slightly under ten to

1978-493: Is also surrounded by a complex, asymmetric envelope , roughly 250 times the size of the star, caused by mass loss from the star itself. The Earth-observed angular diameter of Betelgeuse is exceeded only by those of R Doradus and the Sun. Starting in October 2019, Betelgeuse began to dim noticeably, and by mid-February 2020 its brightness had dropped by a factor of approximately 3, from magnitude 0.5 to 1.7. It then returned to

2064-482: Is clear that the Hipparcos data still contain systematic errors of unknown origin." Although the radio data also have systematic errors, the Harper solution combines the datasets in the hope of mitigating such errors. An updated result from further observations with ALMA and e-Merlin gives a parallax of 4.51 ± 0.8 mas and a distance of 222 +34 −48 pc or 724 +111 −156 ly. In 2020, new observational data from

2150-657: Is easy to find with the naked eye. It is one of three stars that make up the Winter Triangle asterism , and it marks the center of the Winter Hexagon . It can be seen rising in the east at the beginning of January of each year, just after sunset. Between mid-September and mid-March (best in mid-December), it is visible to virtually every inhabited region of the globe, except in Antarctica at latitudes south of 82°. In May (moderate northern latitudes) or June (southern latitudes),

2236-535: Is expected to end its evolution with a supernova explosion, most likely within 100,000 years. When Betelgeuse explodes, it will shine as bright as the half-Moon for more than three months; life on Earth will be unharmed. Having been ejected from its birthplace in the Orion OB1 association  – which includes the stars in Orion's Belt  – this runaway star has been observed to be moving through

2322-411: Is generally considered to be a single isolated star and a runaway star , not currently associated with any cluster or star-forming region, although its birthplace is unclear. Two spectroscopic companions to Betelgeuse have been proposed. Analysis of polarization data from 1968 through 1983 indicated a close companion with a periodic orbit of about 2.1 years, and by using speckle interferometry ,

2408-517: Is listed in the General Catalogue of Variable Stars with a possible period of 2,335 days. More detailed analyses have shown a main period near 400 days, a short period of 185 days, and a longer secondary period around 2,100 days. The lowest reliably-recorded V-band magnitude of +1.614 was reported in February 2020. Radial pulsations of red supergiants are well-modelled and show that periods of

2494-534: Is negligible, so the classical photosphere can be directly seen; in the mid-infrared the scattering increases once more, causing the thermal emission of the warm atmosphere to increase the apparent diameter. Studies with the IOTA and VLTI published in 2009 brought strong support to the idea of dust shells and a molecular shell (MOLsphere) around Betelgeuse, and yielded diameters ranging from 42.57 to 44.28 mas with comparatively insignificant margins of error. In 2011,

2580-728: Is no data on Betelgeuse in Gaia Data Release 2 , which was released in 2018. Betelgeuse is classified as a semiregular variable star , indicating that some periodicity is noticeable in the brightness changes, but amplitudes may vary, cycles may have different lengths, and there may be standstills or periods of irregularity. It is placed in subgroup SRc; these are pulsating red supergiants with amplitudes around one magnitude and periods from tens to hundreds of days. Betelgeuse typically shows only small brightness changes near to magnitude +0.5, although at its extremes it can become as bright as magnitude 0.0 or as faint as magnitude +1.6. Betelgeuse

2666-463: Is proposed that this is due to granulation , similar to the same effect on the sun but on a much larger scale. On 13 December 1920, Betelgeuse became the first star outside the Solar System to have the angular size of its photosphere measured. Although interferometry was still in its infancy, the experiment proved a success. The researchers, using a uniform disk model, determined that Betelgeuse had

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2752-401: Is subject to multiple cycles of increasing and decreasing brightness due to changes in its size and temperature. The astronomers who first noted the dimming of Betelgeuse, Villanova University astronomers Richard Wasatonic and Edward Guinan , and amateur Thomas Calderwood, theorize that a coincidence of a normal 5.9 year light-cycle minimum and a deeper-than-normal 425 day period are

2838-403: Is usually the tenth-brightest star in the night sky and, after Rigel , the second-brightest in its constellation. It is a distinctly reddish, semiregular variable star whose apparent magnitude , varying between +0.0 and +1.6, has the widest range displayed by any first-magnitude star . Betelgeuse is the brightest star in the night sky at near-infrared wavelengths. Its Bayer designation

2924-503: The American Association of Variable Star Observers (AAVSO) show a maximum brightness of 0.2 in 1933 and 1942, and a minimum of 1.2, observed in 1927 and 1941. This variability in brightness may explain why Johann Bayer , with the publication of his Uranometria in 1603, designated the star alpha , as it probably rivaled the usually brighter Rigel ( beta ). From Arctic latitudes, Betelgeuse's red colour and higher location in

3010-475: The Cavendish Astrophysics Group , the new technique employed a small mask with several holes in the telescope pupil plane, converting the aperture into an ad hoc interferometric array. The technique contributed some of the most accurate measurements of Betelgeuse while revealing bright spots on the star's photosphere. These were the first optical and infrared images of a stellar disk other than

3096-553: The Emerald planetariums LITE series, at 42lbs to 62lbs, and the Digitalis Education Solutions, Inc Digitarium Iota and Delta 3, at 20.6 and 33.5 lbs, respectively. Many planetariums use several, more conventional video projectors with special lenses, software and video servers instead of special planetarium projectors. Betelgeuse Betelgeuse is a red supergiant star in the constellation of Orion . It

3182-548: The European Space Agency 's current Gaia mission was not expected to produce good results for stars brighter than the approximately V=6 saturation limit of the mission's instruments, actual operation has shown good performance on objects to about magnitude +3. Forced observations of brighter stars mean that final results should be available for all bright stars and a parallax for Betelgeuse will be published an order of magnitude more accurate than currently available. There

3268-483: The Sun , taken first from ground-based interferometers and later from higher-resolution observations of the COAST telescope . The "bright patches" or "hotspots" observed with these instruments appeared to corroborate a theory put forth by Schwarzschild decades earlier of massive convection cells dominating the stellar surface. In 1995, the Hubble Space Telescope 's Faint Object Camera captured an ultraviolet image with

3354-461: The Very Large Array (VLA) produced a radio solution of 5.07 ± 1.10 mas , equaling a distance of 197 ± 45 pc or 643 ± 146 ly . As the researcher, Harper, points out: "The revised Hipparcos parallax leads to a larger distance ( 152 ± 20 pc ) than the original; however, the astrometric solution still requires a significant cosmic noise of 2.4 mas. Given these results it

3440-477: The interstellar medium at a speed of 30 km/s , creating a bow shock over four light-years wide. Betelgeuse became the first extrasolar star whose photosphere 's angular size was measured in 1920, and subsequent studies have reported an angular diameter (i.e., apparent size) ranging from 0.042 to 0.056 arcseconds ; that range of determinations is ascribed to non-sphericity, limb darkening , pulsations and varying appearance at different wavelengths . It

3526-612: The 19th century, before modern systems of stellar classification , Angelo Secchi included Betelgeuse as one of the prototypes for his Class III (orange to red) stars. Three centuries before Ptolemy, in contrast, Chinese astronomers observed Betelgeuse as yellow ; Such an observation, if accurate, could suggest the star was in a yellow supergiant phase around this time, a credible possibility, given current research into these stars' complex circumstellar environment. Aboriginal groups in South Australia have shared oral tales of

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3612-560: The Earth orbits the Sun, every star is seen to shift by a fraction of an arc second, which measure, combined with the baseline provided by the Earth's orbit gives the distance to that star. Since the first successful parallax measurement by Friedrich Bessel in 1838, astronomers have been puzzled by Betelgeuse's apparent distance. Knowledge of the star's distance improves the accuracy of other stellar parameters, such as luminosity that, when combined with an angular diameter, can be used to calculate

3698-529: The European name. In English, there are four common pronunciations of this name, depending on whether the first e is pronounced short or long and whether the s is pronounced /s/ or /z/ : In 2016, the International Astronomical Union organized a Working Group on Star Names (WGSN) to catalog and standardize proper names for stars. The WGSN's first bulletin, issued July 2016, included

3784-504: The Solar System for comparison, the orbit of Mars is about 1.5 AU , Ceres in the asteroid belt 2.7 AU , Jupiter 5.5 AU —so, assuming Betelgeuse occupying the place of the Sun, its photosphere might extend beyond the Jovian orbit, not quite reaching Saturn at 9.5 AU . The precise diameter has been hard to define for several reasons: The generally reported radii of large cool stars are Rosseland radii , defined as

3870-431: The Sun is below the horizon). Betelgeuse is a variable star whose visual magnitude ranges between 0.0 and +1.6 . There are periods during which it surpasses Rigel to become the sixth brightest star, and occasionally it will become even brighter than Capella . At its faintest, Betelgeuse can fall behind Deneb and Beta Crucis , themselves both slightly variable, to be the twentieth-brightest star. Betelgeuse has

3956-629: The VLTI AMBER instrument. In 2009 it was announced that the radius of Betelgeuse had shrunk from 1993 to 2009 by 15%, with the 2008 angular measurement equal to 47.0 mas . Unlike most earlier papers, this study used measurements at one specific wavelength over 15 years. The diminution in Betelgeuse's apparent size equates to a range of values between 56.0 ± 0.1 mas seen in 1993 to 47.0 ± 0.1 mas seen in 2008—a contraction of almost 0.9 AU in 15 years . The observed contraction

4042-405: The complex circumstellar shells surrounding the supergiant, causing them to suspect the presence of huge gas bubbles resulting from convection. However, it was not until the late 1980s and early 1990s, when Betelgeuse became a regular target for aperture masking interferometry , that breakthroughs occurred in visible-light and infrared imaging . Pioneered by J.E. Baldwin and colleagues of

4128-516: The courtyard, a large sundial . The corridors host astronomy-related exhibits. The Planetarium's meteorological and seismological stations conduct regular observations and host educational classes. 50°17′25.69″N 18°59′29.29″E  /  50.2904694°N 18.9914694°E  / 50.2904694; 18.9914694 This article about a Polish building or structure is a stub . You can help Misplaced Pages by expanding it . Planetarium projector A planetarium projector , also known as

4214-475: The dimming could have come from a short-term minimum coinciding with a long-term minimum producing a grand minimum, a 416-day cycle and 2010 day cycle respectively, a mechanism first suggested by astronomer L. Goldberg . In April 2023, astronomers reported the star reached a peak of 0.0 visual and 0.1 V-band magnitude. As a result of its distinctive orange-red color and position within Orion, Betelgeuse

4300-553: The distance of Betelgeuse, with proposed distances as high as 400 pc or about 1,300 ly . Before the publication of the Hipparcos Catalogue (1997), there were two slightly conflicting parallax measurements for Betelgeuse. The first, in 1991, gave a parallax of 9.8 ± 4.7  mas , yielding a distance of roughly 102 pc or 330 ly . The second was the Hipparcos Input Catalogue (1993) with

4386-453: The driving factors. Other possible causes hypothesized by late 2019 were an eruption of gas or dust or fluctuations in the star's surface brightness. By August 2020, long-term and extensive studies of Betelgeuse, primarily using ultraviolet observations by the Hubble Space Telescope , had suggested that the unexpected dimming was probably caused by an immense amount of superhot material ejected into space. The material cooled and formed

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4472-419: The electromagnetic spectrum—the visible, near-infrared ( NIR ), mid-infrared (MIR), or radio—produce very different angular measurements. In 1996, Betelgeuse was shown to have a uniform disk of 56.6 ± 1.0 mas . In 2000, a Space Sciences Laboratory team measured a diameter of 54.7 ± 0.3 mas , ignoring any possible contribution from hotspots, which are less noticeable in the mid-infrared. Also included

4558-451: The existence of surrounding dust and gas shells would give a diameter of 41.9 mas . To overcome these challenges, researchers have employed various solutions. Astronomical interferometry, first conceived by Hippolyte Fizeau in 1868, was the seminal concept that has enabled major improvements in modern telescopy and led to the creation of the Michelson interferometer in the 1880s, and

4644-490: The first successful measurement of Betelgeuse. Just as human depth perception increases when two eyes instead of one perceive an object, Fizeau proposed the observation of stars through two apertures instead of one to obtain interferences that would furnish information on the star's spatial intensity distribution. The science evolved quickly and multiple-aperture interferometers are now used to capture speckled images , which are synthesized using Fourier analysis to produce

4730-522: The ground between May and August because it is too close to the Sun. Before entering its 2020 conjunction with the Sun, Betelgeuse had reached a brightness of +0.4 . Observations with the STEREO-A spacecraft made in June and July 2020 showed that the star had dimmed by 0.5 since the last ground-based observation in April. This is surprising, because a maximum was expected for August/September 2020, and

4816-479: The most likely explanation for the dimming of the star. A study that uses observations at submillimetre wavelengths rules out significant contributions from dust absorption. Instead, large starspots appear to be the cause for the dimming. Followup studies, reported on 31 March 2020 in The Astronomer's Telegram , found a rapid rise in the brightness of Betelgeuse. Betelgeuse is almost unobservable from

4902-401: The most likely solution for Betelgeuse's 2170-day secondary periodicity, fluctuating radial velocity, moderate radius and low variation in effective temperature. The candidate companion would have a semi-major axis of 8.60 ± 0.33 AU . Parallax is the apparent change of the position of an object, measured in seconds of arc, caused by the change of position of the observer of that object. As

4988-449: The next minimum should occur around April 2021. However Betelgeuse's brightness is known to vary irregularly, making predictions difficult. The fading could indicate that another dimming event might occur much earlier than expected. On 30 August 2020, astronomers reported the detection of a second dust cloud emitted from Betelgeuse, and associated with recent substantial dimming (a secondary minimum on 3 August) in luminosity of

5074-410: The past and future. In more recent years, planetaria — or dome theaters — have broadened their offerings to include wide-screen or "wraparound" films, fulldome video , and laser shows that combine music with laser-drawn patterns. The newest generation of planetariums such as Evans & Sutherland 's Digistar 7 , Global Immersion 's Fidelity or Sky-Skan 's DigitalSky Dark Matter , offer

5160-506: The photosphere. Betelgeuse is the brightest near-infrared source in the sky with a J band magnitude of −2.99; only about 13% of the star's radiant energy is emitted as visible light. If human eyes were sensitive to radiation at all wavelengths, Betelgeuse would appear as the brightest star in the night sky. Catalogues list up to nine faint visual companions to Betelgeuse. They are at distances of about one to four arc-minutes and all are fainter than 10th magnitude. Betelgeuse

5246-488: The physical radius and effective temperature ; luminosity and isotopic abundances can also be used to estimate the stellar age and mass . When the first interferometric studies were performed on the star's diameter in 1920, the assumed parallax was 0.0180 ″ . This equated to a distance of 56  pc or roughly 180  ly , producing not only an inaccurate radius for the star but every other stellar characteristic. Since then, there has been ongoing work to measure

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5332-401: The possibility of a close companion contributing to the overall flux has never been fully ruled out. High-resolution interferometry of Betelgeuse and its vicinity, far beyond the technology of the 1980s and 1990s, has not detected any companions. A more recent study found that a not yet directly-observed, dust-modulating stellar-mass companion of 1.17 ± 0.7   M ☉ would be

5418-531: The process by which mass is lost remains a mystery. With advances in interferometric methodologies, astronomers may be close to resolving this conundrum. Images released by the European Southern Observatory in July 2009, taken by the ground-based Very Large Telescope Interferometer (VLTI), showed a vast plume of gas extending 30 AU from the star into the surrounding atmosphere. This mass ejection

5504-444: The radius of the photosphere at a specific optical depth of two-thirds. This corresponds to the radius calculated from the effective temperature and bolometric luminosity. The Rosseland radius differs from directly measured radii, with corrections for limb darkening and the observation wavelength. For example, a measured angular diameter of 55.6 mas would correspond to a Rosseland mean diameter of 56.2 mas, while further corrections for

5590-404: The ratio of the fundamental to overtone periods gives valuable information about the internal structure of the star and its age. The source of the long secondary periods is unknown, but they cannot be explained by radial pulsations . Interferometric observations of Betelgeuse have shown hotspots that are thought to be created by massive convection cells, a significant fraction of the diameter of

5676-488: The red supergiant can be seen briefly on the western horizon after sunset, reappearing again a few months later on the eastern horizon before sunrise. In the intermediate period (June–July, centered around mid June), it is invisible to the naked eye (visible only with a telescope in daylight), except around midday low in the north in Antarctic regions between 70° and 80° south latitude (during midday twilight in polar night , when

5762-453: The sky than Rigel meant the Inuit regarded it as brighter, and one local name was Ulluriajjuaq ("large star"). In 1920, Albert A. Michelson and Francis G. Pease mounted a six-meter interferometer on the front of the 2.5-meter telescope at Mount Wilson Observatory , helped by John August Anderson . The trio measured the angular diameter of Betelgeuse at 0.047 ″ , a figure that resulted in

5848-601: The solar atmosphere. Astronomers saw some major advances in astronomical imaging technology in the 1970s, beginning with Antoine Labeyrie 's invention of speckle interferometry , a process that significantly reduced the blurring effect caused by astronomical seeing . It increased the optical resolution of ground-based telescopes , allowing for more precise measurements of Betelgeuse's photosphere. With improvements in infrared telescopy atop Mount Wilson , Mount Locke , and Mauna Kea in Hawaii, astrophysicists began peering into

5934-503: The southwestern quadrant 2,000  K hotter than the stellar surface. Subsequent ultraviolet spectra taken with the Goddard High Resolution Spectrograph suggested that the hot spot was one of Betelgeuse's poles of rotation. This would give the rotational axis an inclination of about 20° to the direction of Earth, and a position angle from celestial North of about 55°. In a study published in December 2000,

6020-470: The space-based Solar Mass Ejection Imager aboard the Coriolis satellite and three different modeling techniques produced a refined parallax of 5.95 +0.58 −0.85 mas, a radius of 764 +116 −62 R ☉ , and a distance of 168.1 +27.5 −14.4 pc or 548 +90 −49 ly, which, if accurate, would mean Betelgeuse is nearly 25% smaller and 25% closer to Earth than previously thought. Although

6106-460: The star and each emitting 5–10% of the total light of the star. One theory to explain long secondary periods is that they are caused by the evolution of such cells combined with the rotation of the star. Other theories include close binary interactions, chromospheric magnetic activity influencing mass loss, or non-radial pulsations such as g-modes . In addition to the discrete dominant periods, small-amplitude stochastic variations are seen. It

6192-488: The star had shrunk by 15% since 1993 at an increasing rate without a significant diminution in magnitude. Subsequent observations suggest that the apparent contraction may be due to shell activity in the star's extended atmosphere. In addition to the star's diameter, questions have arisen about the complex dynamics of Betelgeuse's extended atmosphere. The mass that makes up galaxies is recycled as stars are formed and destroyed , and red supergiants are major contributors, yet

6278-480: The star showed signs of rebrightening. On 22 February 2020, Betelgeuse may have stopped dimming altogether, all but ending the dimming episode. On 24 February 2020, no significant change in the infrared over the last 50 years was detected; this seemed unrelated to the recent visual fading and suggested that an impending core collapse may be unlikely. Also on 24 February 2020, further studies suggested that occluding "large-grain circumstellar dust " may be

6364-626: The star's diameter was measured with the Infrared Spatial Interferometer (ISI) at mid-infrared wavelengths producing a limb-darkened estimate of 55.2 ± 0.5  mas – a figure entirely consistent with Michelson's findings eighty years earlier. At the time of its publication, the estimated parallax from the Hipparcos mission was 7.63 ± 1.64 mas , yielding an estimated radius for Betelgeuse of 3.6 AU . However, an infrared interferometric study published in 2009 announced that

6450-498: The star. In June 2021, the dust was explained as possibly caused by a cool patch on its photosphere and in August a second independent group confirmed these results. The dust is thought to have resulted from the cooling of gas ejected from the star. An August 2022 study using the Hubble Space Telescope confirmed previous research and suggested the dust could have been created by a surface mass ejection. It conjectured as well that

6536-429: The team concluded that the closer of the two companions was located at 0.06″ ± 0.01″ (≈9 AU) from the main star with a position angle of 273°, an orbit that would potentially place it within the star's chromosphere . The more distant companion was at 0.51″ ± 0.01″ (≈77 AU) with a position angle of 278°. Further studies have found no evidence for these companions or have actively refuted their existence, but

6622-483: The top 10 brightest stars in the sky to outside the top 20, noticeably dimmer than its near neighbor Aldebaran . Mainstream media reports discussed speculation that Betelgeuse might be about to explode as a supernova, but astronomers note that the supernova is expected to occur within approximately the next 100,000 years and is thus unlikely to be imminent. By 17 February 2020, Betelgeuse's brightness had remained constant for about 10 days, and

6708-683: The variable brightness of Betelgeuse for at least 1,000 years. The variation in Betelgeuse's brightness was described in 1836 by Sir John Herschel in Outlines of Astronomy . From 1836 to 1840, he noticed significant changes in magnitude when Betelgeuse outshone Rigel in October 1837 and again in November 1839. A 10-year quiescent period followed; then in 1849, Herschel noted another short cycle of variability, which peaked in 1852. Later observers recorded unusually high maxima with an interval of years, but only small variations from 1957 to 1967. The records of

6794-525: The work of Martin Schwarzschild and his colleague at Princeton University , Richard Härm. This book disseminated ideas on how to apply computer technologies to create stellar models, while the Stratoscope projects, by taking balloon-borne telescopes above the Earth's turbulence , produced some of the finest images of solar granules and sunspots ever seen, thus confirming the existence of convection in

6880-406: Was 43.33 ± 0.04 mas . The study also put forth an explanation as to why varying wavelengths from the visible to mid-infrared produce different diameters: the star is seen through a thick, warm extended atmosphere. At short wavelengths (the visible spectrum) the atmosphere scatters light, thus slightly increasing the star's diameter. At near-infrared wavelengths ( K and L bands ), the scattering

6966-473: Was a framework that held nearly 150 individual projectors, including those dedicated to the planets, the Sun, and specific stars. Each globe held representations of almost 4,500 stars per hemisphere. The "stars" were created by tiny holes that were punched into copper foil, ranging from 0.023 to 0.452 mm in size, the larger holes letting more light get through and thereby creating brighter star images. Two glass plates held this foil between them to create what

7052-438: Was a theoretical allowance for limb darkening, yielding a diameter of 55.2 ± 0.5 mas . The earlier estimate equates to a radius of roughly 5.6 AU or 1,200  R ☉ , assuming the 2008 Harper distance of 197.0 ± 45 pc , a figure roughly the size of the Jovian orbit of 5.5 AU . In 2004, a team of astronomers working in the near-infrared announced that the more accurate photospheric measurement

7138-459: Was called a "star field plate". Each globe was illuminated using a 1,500-watt lamp that was located in its center. A number of aspherical condenser lenses were placed within each globe to focus the light onto the plates. Twenty-three of the most prominent stars had their own projectors, designed to project a small disk instead of pinpoint of light, and were also colored: Betelgeuse and Antares would appear reddish, Rigel and Spica would each have

7224-580: Was cast millions of miles from the star, and then cooled to form the dust that caused the dimming. The star's designation is α Orionis (Latinised to Alpha Orionis ), given by Johann Bayer in 1603. The traditional name Betelgeuse was derived from the Arabic يد الجوزاء Yad al-Jawzā’ "the hand of al-Jawzā’ [i.e. Orion]". An error in the 13th-century reading of the Arabic initial yā’ ( يـ ) as bā’ ( بـ —a difference in i‘jām ) led to

7310-424: Was equal to the distance between the Sun and Neptune and is one of multiple events occurring in Betelgeuse's surrounding atmosphere. Astronomers have identified at least six shells surrounding Betelgeuse. Solving the mystery of mass loss in the late stages of a star's evolution may reveal those factors that precipitate the explosive deaths of these stellar giants. A pulsating semiregular variable star , Betelgeuse

7396-488: Was reported still fainter in February in The Astronomer's Telegram at a record minimum of +1.614, noting that the star is currently the "least luminous and coolest" in the 25 years of their studies and also calculating a decrease in radius. Astronomy magazine described it as a "bizarre dimming", and popular speculation inferred that this might indicate an imminent supernova . This dropped Betelgeuse from one of

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