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Beta Ceti (β Ceti, abbreviated Beta Cet, β Cet), officially named Diphda Template:IPAc-en,<ref name=IAUnaming/> is the brightest star in the constellation of Cetus. Although designated 'beta', it is actually brighter than the 'alpha' star in the constellation, Menkar, by half a magnitude. This orange giant is easy to identify due to its location in an otherwise dark section of the celestial sphere. Based on parallax measurements, it lies at an estimated distance of Template:Convert from the Sun.<ref name=aaa474_2_653/>

PropertiesEdit

File:Bceti xray.jpg
Image of orange giant Beta Ceti from NASA's Chandra X-ray Observatory.
File:BetaCetLightCurve.png
An extreme ultraviolet light curve for Beta Ceti, adapted from Ayres et al. (2001)<ref name=apj562_1_L83/>


Diphda has an apparent visual magnitude of 2.02,<ref name=clpl4_99/> making it the brightest star in Cetus. It has a stellar classification of K0 III,<ref name=mnras328_1_45/> although some sources list a classification of G9.5 III<ref name=sagesser_jordan2005/> indicating that it lies along the dividing line separating G-type from K-type stars. The luminosity class 'III' means that it is a giant, a star that has consumed the hydrogen at its core and evolved away from the main sequence. With a mass of 3.5 solar masses, Beta Ceti was a B-type star when it formed on the main sequence.<ref name=Tsvetkova/> After passing through the red giant stage, it underwent a helium flash event and is now a red clump star generating energy through the thermonuclear fusion of helium at its core.<ref name=apj562_1_L83/> Beta Ceti will remain in this mode for over 100 million years.<ref name=chandra/>

The effective temperature of the star's outer envelope is about Template:Val,<ref name=aj135_1_209/> giving it the characteristic orange hue of a K-type star.<ref name=csiro/> In spite of its cooler temperature, Diphda is much more luminous than the Sun with a luminosity of about 150 times that of the Sun, while its photosphere has swollen to around 18<ref name=reffert/> times the size of the Sun, in contrast with the initial radius of Template:Solar radius when still in the main sequence.<ref name=Tsvetkova/>

This star displays flaring activity that results in random outbursts that increase the luminosity of the star over intervals lasting several days. This is a much longer duration than for comparable solar flare activity on the Sun, which typically last for periods measured in hours.<ref name=apj562_1_L83/> In 2005, a relatively high rate of X-ray emission was detected with the XMM-Newton space observatory.<ref name=sagesser_jordan2005/> It is emitting about 2,000 times the X-ray luminosity of the Sun, allowing the star to be imaged with the Chandra X-ray Observatory.<ref name=chandra/>

NomenclatureEdit

β Ceti (Latinised to Beta Ceti) is the star's Bayer designation.

It bore the traditional names Diphda and Deneb Kaitos Template:IPAc-en.<ref name="Kunitzsch"/> Diphda is Arabic for 'frog', from the phrase ضفدع الثاني aḍ-ḍifdaʿ aṯ-ṯānī 'the second frog' (the 'first frog' is Fomalhaut). Deneb Kaitos is from الذنب القيتوس الجنوب Al Dhanab al Ḳaiṭos al Janūbīyy 'southern tail of Cetus'.<ref name=allen1963/>

In 2016, the International Astronomical Union organized a Working Group on Star Names (WGSN)<ref name="WGSN"/> to catalogue and standardize proper names for stars. The WGSN approved the name Diphda for this star on 21 August 2016 and it is now so entered in the IAU Catalog of Star Names.<ref name="IAU-CSN"/>

In Chinese astronomy, Deneb Kaitos is called 土司空, Pinyin: Tǔsīkōng, meaning Master of Constructions, because this star is marking itself and stands alone in the Master of Constructions asterism, Legs mansion (see : Chinese constellation).<ref name=zh/> 土司空 (Tǔsīkōng), westernized into Too Sze Kung by R.H. Allen and the meaning is "Superintendent of Earthworks."<ref name=TSK/>

NamesakeEdit

USS Diphda (AKA-59) was a U.S. Navy ship.

See alsoEdit

ReferencesEdit

Template:Reflist

External linksEdit

Template:Stars of Cetus