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DD Hydrae

DD Hydrae Facts

DD Hydrae's Alternative Names

HIP40186 is the reference name for the star in the Hipparcos Star Catalogue.

DD Hydrae has alternative name(s) :- DD Hya, DD Hya.

More details on objects' alternative names can be found at Star Names .

Location of DD Hydrae

The location of the variable star in the night sky is determined by the Right Ascension (R.A.) and Declination (Dec.), these are equivalent to the Longitude and Latitude on the Earth. The Right Ascension is how far expressed in time (hh:mm:ss) the star is along the celestial equator. If the R.A. is positive then its eastwards. The Declination is how far north or south the object is compared to the celestial equator and is expressed in degrees. For DD Hydrae, the location is 08h 12m 31.81 and +02° 50` 05.1 .

Physical Properties (Colour) of DD Hydrae

DD Hydrae Colour and Temperature

DD Hydrae has a spectral type of A-F. This means the star is a blue variable star. The star's Iron Abundance is -0.97 with an error value of 9.99 Fe/H with the Sun has a value of 1 to put it into context.

DD Hydrae Apparent and Absolute Magnitudes

DD Hydrae has an apparent magnitude of 12.37 which is how bright we see the star from Earth. Apparent Magnitude is also known as Visual Magnitude. Using the supplied Parallax value, you would get an absolute magnitude of Magnitude, whether it be apparent/visual or absolute magnitude is measured by a number, the smaller the number, the brighter the Star is. Our own Sun is the brightest star and therefore has the lowest of all magnitudes, -26.74. A faint star will have a high number.

Distance to DD Hydrae

Using the original Hipparcos data that was released in 1997, the parallax to the star was given as -1.50 which gave the calculated distance to DD Hydrae as -2174.42 light years away from Earth or -666.67 parsecs. It would take a spaceship travelling at the speed of light, -2174.42 years to get there. We don't have the technology or spaceship that can carry people over that distance yet.

Variable Type of DD Hydrae

The star is a pulsating RR Lyrae type with a variable type which means that its size changes over time. The Variable Type is usually named after the first star of that type to be spotted. DD Hydrae brightness ranges from a magnitude of 12.952 to a magnitude of 11.491 over its variable period. The smaller the magnitude, the brighter the star. Its variable/pulsating period lasts for 0.5 days (variability).

Source of Information

The source of the information if it has a Hip I.D. is from Simbad, the Hipparcos data library based at the University at Strasbourg, France. Hipparcos was a E.S.A. satellite operation launched in 1989 for four years. The items in red are values that I've calculated so they could well be wrong. Information regarding Metallicity and/or Mass is from the E.U. Exoplanets. The information was obtained as of 12th Feb 2017.

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Additional DD Hydrae Facts and Figures

Visual Facts


Primary / Proper / Traditional NameDD Hydrae
Alternative NamesDD Hya, HIP 40186, DD Hya
Spectral TypeA-F
Constellation's Main StarNo
Multiple Star SystemNo / Unknown
Star TypeVariable Star
ColourBlue
GalaxyMilky Way
ConstellationHydra
Visual / Apparent Magnitude12.37
Naked Eye VisibleRequires a 4.5 - 6 Inch Telescope - Magnitudes
Right Ascension (R.A.)08h 12m 31.81
Declination (Dec.)+02° 50` 05.1
Galactic Latitude19.30 degrees
Galactic Longitude219.86 degrees
Distance from Earth-1.50 Parallax (milliarcseconds)
 -2174.42 Light Years
 -666.67 Parsecs
 -137,509,600.20 Astronomical Units
B-V Index-99.00
Radial Velocity156.00 ± 3.00 km/s
Iron Abundance-0.97 ± 9.99 Fe/H

Companions (Multi-Star and Exoplanets) Facts


Exoplanet CountNone/Unaware

Variable Star Details


Variable Star ClassPulsating
Variable Star TypeRR Lyrae type with a
Mean Variability Period in Days0.502
Variable Magnitude Range (Brighter - Dimmer)11.491 - 12.952

Sources and Links


SIMBAD SourceLink

Related Stars


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