Universe Guide


HD 137388, HIP76351

HD 137388 is a orange to red main sequence dwarf star that can be located in the constellation of Apus. HD 137388 is the brightest star in Apus based on the Hipparcos 2007 apparent magnitude. The star can not be seen by the naked eye, you need a telescope to see it. It is calculated at being 6.450 Billion Years old. This information comes from ExoPlanet.

HIP76351 is the reference name for the star in the Hipparcos Star Catalogue. The Id of the star in the Henry Draper catalogue is HD137388. HD 137388 has at least 1 Extrasolar Planets believed to be in orbit around the star.

Location of HD 137388

The location of the star in the galaxy 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 star is compared to the celestial equator and is expressed in degrees. For HD 137388, the location is 15h 35m 40.09 and -80d12`16.9 .

Proper Motion of HD 137388

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 43.31 ± 0.87 miliarcseconds/year towards the north and -46.72 ± 1.04 miliarcseconds/year east if we saw them in the horizon.

Physical Properties (Colour, Temperature, Metallicity, Age, Mass, Radius) of HD 137388

HD 137388 has a spectral type of K0/K1V. This means the star is a orange to red main sequence dwarf star. The star is 7376.00000000 Parsecs from the Galactic Centre or terms of Light Years is 24057.8082534400000000s. The star has a B-V Colour Index of 0.89 which means the star's temperature has been calculated using information from Morgans @ Uni.edu at being 5,074 Kelvin.

HD 137388 Radius has been calculated as being 0.84 times bigger than the Sun.The Sun's radius is 695,800km, therefore the star's radius is an estimated 584,292.16.km. However with the 2007 release of updated Hipparcos files, the radius is now calculated at being round 0.86. The figure is derived at by using the formula from SDSS and has been known to produce widely incorrect figures. The star's solar mass is 0.86 times that of the Sun's. The Sun's Mass is 1,989,100,000,000,000,000,000 billion kg. which to calculate using this website is too large. To give idea of size, the Sun is 99.86% the mass of the solar system.

The star's metallicity is 0.180000, this value is the fractional amount of the star that is not Hydrogen (X) or Helium (Y). An older star would have a high metallicity whereas a new star would have a lower one.

The star is believed to be about 6.45 Billion years old. To put in context, the Sun is believed to be about five billion years old and the Universe is about 13.8 billion years old.

HD 137388 Apparent and Absolute Magnitudes

HD 137388 has an apparent magnitude of 8.71 which is how bright we see the star from Earth. Apparent Magnitude is also known as Visual Magnitude. If you used the 1997 Parallax value, you would get an absolute magnitude of 5.79 If you used the 2007 Parallax value, you would get an absolute magnitude of 5.74. 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 HD 137388

Using the original Hipparcos data that was released in 1997, the parallax to the star was given as 26.01 which gave the calculated distance to HD 137388 as 125.40 light years away from Earth or 38.45 parsecs. It would take a spaceship travelling at the speed of light, 125.40 years to get there. We don't have the technology or spaceship that can carry people over that distance yet.

In 2007, Hipparcos data was revised with a new parallax of 25.49 which put HD 137388 at a distance of 127.96 light years or 39.23 parsecs. It should not be taken as though the star is moving closer or further away from us. It is purely that the distance was recalculated.

The star's Galacto-Centric Distance is 7,376.00 Parsecs or 24,057.81 Light Years. The Galacto-Centric Distance is the distance from the star to the Centre of the Galaxy which is Sagittarius A*.

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.

HD 137388 Facts

Alternative Names

Traditional/Proper NameHD 137388
Hipparcos Library I.D.76351
Henry Draper Designation137388

Visual Facts

Star Typemain sequence dwarf star
Age6.45 Billion Years Old
Absolute Magnitude5.79 / 5.74
Visual / Apparent Magnitude8.71
Naked Eye VisibleRequires a 7x50 Binoculars - Magnitudes
Right Ascension (R.A.)15h 35m 40.09
Declination (Dec.)-80d12`16.9
Galactic Latitude-19.58 degrees
Galactic Longitude309.74 degrees
1997 Distance from Earth26.01 Parallax (milliarcseconds)
 125.40 Light Years
 38.45 Parsecs
2007 Revised Distance from Earth25.49 Parallax (milliarcseconds)
 127.96 Light Years
 39.23 Parsecs
Galacto-Centric Distance24,057.81 Light Years / 7,376.00 Parsecs
Proper Motion Dec.43.31 ± 0.87 milliarcseconds/year
Proper Motion RA.-46.72 ± 1.04 milliarcseconds/year
B-V Index0.89
Radial Velocity26.20 ± 0.30 km/s
Iron Abundance0.16 ± 0.03 Fe/H
Spectral TypeK0/K1V
Colour(K) Orange to Red

Companions (Multi-Star and Exoplanets) Facts

Exoplanet Count1

Estimated Facts

Calculated Effective Temperature5,074 Kelvin
Mass Compared to the Sun0.86

Sources and Links

SIMBAD SourceLink

Related Stars

List of Extrasolar Planets orbiting HD 137388

NameStatusMass (Jupiters)Orbital Period (Days)EccentricityDiscoveredSemi-Major AxisPeriastron
Hd 137388 BConfirmed0.223330.0000.3620110.8986.000

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