About Diphda
Description
Diphda (also known as Deneb Kaitos) is the brightest star in Cetus at magnitude 2.04. It is an orange giant of spectral type K0III, located about 96 light-years from Earth. With a luminosity roughly 145 times that of the Sun and a surface temperature of about 4,800 K, it is a star that has left the main sequence and expanded considerably. Diphda is also a known X-ray source.
Observing Tips
Diphda sits low in the southern sky for northern observers, well below the Great Square of Pegasus. Its warm orange hue is subtle to the naked eye but becomes more apparent in binoculars. It is the anchor star for the otherwise faint constellation Cetus and can be found by drawing a line from Alpha Peg (Markab) through Beta Peg (Scheat) and extending it southward. Best observed from October through January.
History
The name Diphda comes from the Arabic 'al-difda al-thani,' meaning 'the second frog' (the first frog being Fomalhaut). The alternate name Deneb Kaitos means 'tail of the whale' in Arabic, referring to its position in the constellation figure. In Chinese astronomy, it was part of the 'Circular Granary' asterism.
Fun Facts
Diphda is the brightest star in Cetus, yet it carries the Bayer designation Beta — Alpha Ceti (Menkar) is actually fainter. This is one of several cases where Bayer's original magnitude estimates were inaccurate. Diphda is one of the brightest giant stars detected as an X-ray source, likely due to magnetic activity in its outer atmosphere.
Observe
1Physical Properties
2Position & Identifiers
3How easy to spot?
| Equipment | Bortle 3 | Bortle 4 | Bortle 5 |
|---|---|---|---|
| Naked eye Naked eye | Easy | Easy | Easy |
| 50 mm finder 50mm finder | Easy | Easy | Easy |
| 150 mm telescope 150mm scope | Easy | Easy | Easy |
Bortle 3 = rural · 4 = outer suburbs · 5 = suburbs
4Visibility
Set a location in User Settings to see visibility data.
5Survey Image
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Explore
7
Size Comparison
8
Compare Stars
9
Spectral Classification
10
Hertzsprung-Russell Diagram
11
Stellar Lifecycle
12
Blackbody Spectrum
13
Stellar Absorption Spectrum
Simulated absorption spectrum based on spectral type. Hover over lines to identify elements.
14
Stellar Fusion
Discover
15Stellar Notes
16
Light Travel Time Machine
17
Relativistic Travel
Nearby in the Sky
Other targets within a few degrees — pan your scope a little and keep exploring.
Visibility scores assume a 150 mm Newton at Bortle 4.
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