GreenBank Observatory HIP 117779
Channel: Astro Ninja
Date: 2019-06-25

According to https://www.universeguide.com/star/17779/hip17779
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The location of the 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 HIP 17779, the location is 03h 48m 22.34 and +08° 34` 49.5 .

HIP 17779 is a Star type star. HIP 17779 is a G5 star based on the spectral type that was recorded in the Hipparcos star catalogue.
HIP 17779 is not part of the Taurus constellation outline but is within the borders of the constellation.
Based on the spectral type (G5) of the star, the star's colour is yellow .
The star can not be seen by the naked eye, you need a telescope to see it.
Using the most recent figures given by the 2007 Hipparcos data, the star is 404.17 light years away from Earth.


Radial Velocity and Proper Motion


Proper Motion
All stars like planets orbit round a central spot, in the case of planets, its the central star such as the Sun. In the case of a star, its the galactic centre. The constellations that we see today will be different than they were 50,000 years ago or 50,000 years from now. Proper Motion details the movements of these stars and are measured in milliarcseconds. The star is moving -17.74 ± 0.35 milliarcseconds/year towards the north and 92.34 ± 0.72 milliarcseconds/year east if we saw them in the horizon.

Radial Velocity
The Radial Velocity, that is the speed at which the star is moving away/towards the Sun is -1.80000 km/s with an error of about 0.60 km/s . When the value is negative then the star and the Sun are getting closer to one another, likewise, a positive number means that two stars are moving away. Its nothing to fear as the stars are so far apart, they won't collide in our life-time, if ever.

Physical Properties
Colour and Temperature
Based on the star's spectral type of G5 , HIP 17779's colour and type is yellow star. Based on the spectral type, we can deduce that the surface temperature of the star is in the order of between 5,000 and 6,000K based on the notes from Harvard University. To put this in context, the temperature of our Sun is about 5,778 Kelvin as said by Google.

Luminosity
Luminosity is the amount of energy that a star pumps out and its relative to the amount that our star, the Sun gives out. The figure of 22.26 that I have given is based on the value in the Simbad Hipparcos Extended Catalogue at the University of Strasbourg from 2012.

Radius
HIP 17779 estimated radius has been calculated as being 5.93 times bigger than the Sun. The Sun's radius is 695,800km, therefore the star's radius is an estimated 4,128,489.46.km. If you need the diameter of the star, you just need to multiple the radius by 2. However with the 2007 release of updated Hipparcos files, the radius is now calculated at being round 5.64. The figure is derived at by using the formula from SDSS rather than peer reviewed papers. It has been known to produce widely incorrect figures.

Apparent (Brightness) and Absolute Magnitudes
HIP 17779 has an apparent magnitude of 7.40, this is a measure of the brightness of the star as seen from Earth. Apparent Magnitude is also known as Visual Magnitude. If you used the 1997 Parallax value, you would get an absolute magnitude of 1.82 If you used the 2007 Parallax value, you would get an absolute magnitude of 1.93.

Distance: 

Using the 2007 distance, the star is roughly 25,560,156.68 Astronomical Units from the Earth/Sun give or take a few. An Astronomical Unit is the distance between Earth and the Sun. The number of A.U. is the number of times that the star is from the Earth compared to the Sun. The star's Galacto-Centric Distance is 7,502.00 Parsecs or 24,468.77 Light Years. The Galacto-Centric Distance is the distance from the star to the Centre of the Galaxy which is Sagittarius A*.

Alternative Names and Meanings

HIP17779 is the reference name for the star in the Hipparcos Star Catalogue.
The Id of the star in the Henry Draper catalogue is HD23805. The catalogue was started by the American doctor and has been expanded on over the years.
The star is catalogued in the Tycho-2 star catalogue as TYC-658-1098-1. The catalogue lists 2 millions stars and its homepage is E.S.A.
BD number is the number that the star was filed under in the Durchmusterung or Bonner Durchmusterung, a star catalogue that was put together by the Bonn Observatory between 1859 to 1903. The star's BD Number is BD+08 571.
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