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 .
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 .
Based on the star's spectral type of A-F , DD Hydrae's colour and type is blue - white variable star. Based on the star's spectral, the stars temperature is between 7,500.00 and 10,000.00 degrees kelvin.
DD Hydrae 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. The value comes from the Hipparcos Extended Catalog.
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.
Using the original Hipparcos data that was released in 1997, the parallax to the star was given as -1.50000 which gave the calculated distance to DD Hydrae as -2174.42 light years away from Earth or -666.67 parsecs. If you want that in miles, it is about -12,782,600,583,957,905.26, based on 1 Ly = 5,878,625,373,183.61 miles.
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).
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.
|Primary / Proper / Traditional Name||DD Hydrae|
|Alternative Names||DD Hya, HIP 40186, DD Hya|
|Constellation's Main Star||No|
|Multiple Star System||No / Unknown|
|Star Type||Variable Star|
|Visual / Apparent Magnitude||12.37|
|Naked Eye Visible||Requires a 4.5 - 6 Inch Telescope - Magnitudes|
|Right Ascension (R.A.)||08h 12m 31.81|
|Declination (Dec.)||+02° 50` 05.1|
|Galactic Latitude||19.30214724 degrees|
|Galactic Longitude||219.85663753 degrees|
|Distance from Earth||-1.50000 Parallax (milliarcseconds)|
|-2174.42 Light Years|
|-137,509,600.20 Astronomical Units|
|Radial Velocity||156.00000 ± 3.00 km/s|
|Iron Abundance||-0.9700 ± 9.99 Fe/H|
|Variable Star Class||Pulsating|
|Variable Star Type||RR Lyrae type with a|
|Mean Variability Period in Days||0.502|
|Variable Magnitude Range (Brighter - Dimmer)||11.491 - 12.952|
|Calculated Temperature Range||7,500.00 - 10,000.00|
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