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Zosma (Delta Leonis, 68 Leonis) Star Facts

Zosma Facts

  • Zosma is a main sequence star that can be located in the constellation of Leo. The description is based on the spectral class.
  • Zosma is a main star of the constellation outline.
  • Based on the spectral type (A4V) of the star, the star's colour is blue - white .
  • The star can be seen with the naked eye, that is, you don't need a telescope/binoculars to see it.
  • Zosma has a radius that is 2.14 times bigger than the Suns. Radius
  • Using the most recent figures given by the 2007 Hipparcos data, the star is 58.43 light years away from us. Distance

Information on Zosma

Zosma is one of the brightest stars in the constellation of Leo. It is about 2.2x, or read it another way, twice as big as the Sun. Its name is Arabic for Girdle from where it gets its name from, i.e. its location in the constellation. It is one of the brightest in the night sky compared to the other stars but is not the brightest in Leo, that honour goes to Regulus. As it is travelling through the galaxy at a speed of 26.6km/s relative to the Sun, it will come close to the Sun in about 518,000 years when it will brighten in the night sky but not any where near as the Sun or Moon. 1

Although Zosma is fourth brightest evident by the fact it is Delta, the fourth letter of the Greek constellation, it is brighter than the third star, Algieba which is a double star. Zosma is brighter than both stars but it falls in the pecking order because the sum of the brightness of the two Algieba stars is brighter than Zosma. It is a dying star and is over half way through its dying process.2

Zosma's Alternative Names

Delta Leonis (Del Leo) is the Bayer Classification for the star. The Bayer Classification was created by Johann Bayer in 1603. The brightest star in the constellation is normally given the Alpha designation, there are exceptions such as Pollux which is Beta Geminorum.

The Id of the star in the Yale Bright Star Catalogue is HR4357. HIP54872 is the reference name for the star in the Hipparcos Star Catalogue. The Id of the star in the Henry Draper catalogue is HD97603. The Gliese ID of the star is GL 419. The star was part of the original catalogue devised by German Astronomer Wilheim Gliese of stars located within 20 parsecs of Earth. Star Names

Zosma has alternative name(s) :- Duhr.

Flamsteed designations are named after the creator, Sir John Flamsteed. Sir John named the stars in the constellation with a number and its latin name, this star's Flamsteed designation is 68 Leonis. The Flamsteed name can be shortened to 68 Leo.

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+21 2298.

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

Location of Zosma

The location of the main sequence 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 Zosma, the location is 11h 14m 06.41 and +20° 31` 26.5 .

Radial Velocity and Proper Motion of Zosma

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 -129.88 ± 0.15 milliarcseconds/year towards the north and 143.42 ± 0.25 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 -20.90000 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 of Zosma

Zosma Colour and Temperature

Based on the star's spectral type of A4V , Zosma's colour and type is blue - white main sequence star. The star's effective temperature is 8,296 Kelvin which is hotter than our own Sun's effective Temperature which is 5,777 Kelvin.

Zosma 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 25.61 that I have given is based on the value in the Simbad Hipparcos Extended Catalogue at the University of Strasbourg from 2012.

Zosma Radius

Zosma Radius has been calculated as being 2.14 times bigger than the Sun. The Sun's radius is 695,800km, therefore the star's radius is an estimated 1,489,012.00.km. If you need the diameter of the star, you just need to multiple the radius by 2.

Zosma Mass

The Zosma's solar mass is 2.20 times that of our star, the Sun. 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.

Zosma Iron Abundance

Zosma Iron Abundance is -0.18 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.

Zosma Apparent and Absolute Magnitudes

Zosma has an apparent magnitude of 2.56 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 1.32 If you used the 2007 Parallax value, you would get an absolute magnitude of 1.29. 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 Zosma

Using the original Hipparcos data that was released in 1997, the parallax to the star was given as 56.52000 which gave the calculated distance to Zosma as 57.71 light years away from Earth or 17.69 parsecs. If you want that in miles, it is about 339,255,470,286,426.13, based on 1 Ly = 5,878,625,373,183.61 miles.

In 2007, Hipparcos data was revised with a new parallax of 55.82000 which put Zosma at a distance of 58.43 light years or 17.91 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.

Using the 2007 distance, the star is roughly 3,694,176.94 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 7,405.00 Parsecs or 24,152.40 Light Years. The Galacto-Centric Distance is the distance from the star to the Centre of the Galaxy which is Sagittarius A*.

Travel Time to Zosma

The time it will take to travel to this star is dependent on how fast you are going. U.G. has done some calculations as to how long it will take going at differing speeds. A note about the calculations, when I'm talking about years, I'm talking non-leap years only (365 days).

The New Horizons space probe is the fastest probe that we've sent into space at the time of writing. Its primary mission was to visit Pluto which at the time of launch (2006), Pluto was still a planet.

DescriptionSpeed (m.p.h.)Time (years)
Walking49,796,032,408.12
Car120326,534,413.60
Airbus A38073653,239,306.57
Speed of Sound (Mach 1)767.26951,069,611.35
Concorde (Mach 2)1,534.5425,534,772.40
New Horizons Probe33,0001,187,397.87
Speed of Light670,616,629.0058.43

Meteor Showers Radiating from near Zosma

The Daytime delta Leonids Meteor Shower radiants from a point near this star. The speed of a meteor in the shower is 31 Km/s.

The December delta Leonids Meteor Shower radiants from a point near this star. The speed of a meteor in the shower is 63 Km/s.

The delta Leonid Complex Meteor Shower radiants from a point near this star. The speed of a meteor in the shower is 20 Km/s.

The Delta Leonids Meteor Shower radiants from a point near this star. The meteor shower runs typically between Feb 15 - Mar 10 with a peak date of Feb 25. The speed of a meteor in the shower is 23 Km/s. The amount of meteors predicted to be seen per hour (Zenith Hourly Rate) is 23.

The May Delta Leonids Meteor Shower radiants from a point near this star. The meteor shower runs typically between with a peak date of 15th May. The speed of a meteor in the shower is 7 Km/s.

The Northern delta Leonids Meteor Shower radiants from a point near this star. The meteor shower runs typically between with a peak date of 27th February. The speed of a meteor in the shower is 20 Km/s.

The Southern delta Leonids Meteor Shower radiants from a point near this star. The meteor shower runs typically between with a peak date of 23rd February. The speed of a meteor in the shower is 17 Km/s.

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 Zosma Facts and Figures

Visual Facts


Primary / Proper / Traditional NameZosma
Alternative NamesDelta Leonis, Del Leo, Duhr, HD 97603, HIP 54872, HR 4357, 68 Leonis, 68 Leo, BD+21 2298, Gliese 419
Spectral TypeA4V
Constellation's Main StarYes
Multiple Star SystemYes
Star Type Main Sequence Dwarf Star
ColourBlue
GalaxyMilky Way
ConstellationLeo
Absolute Magnitude 1.32 / 1.29
Visual / Apparent Magnitude2.56
Naked Eye VisibleYes - Magnitudes
Right Ascension (R.A.)11h 14m 06.41
Declination (Dec.)+20° 31` 26.5
Galactic Latitude66.82731038 degrees
Galactic Longitude224.22743328 degrees
1997 Distance from Earth56.52000 Parallax (milliarcseconds)
 57.71 Light Years
 17.69 Parsecs
2007 Distance from Earth55.82000 Parallax (milliarcseconds)
 58.43 Light Years
 17.91 Parsecs
 3,694,176.94 Astronomical Units
Galacto-Centric Distance24,152.40 Light Years / 7,405.00 Parsecs
Proper Motion Dec.-129.88000 ± 0.15000 milliarcseconds/year
Proper Motion RA.143.42000 ± 0.25000 milliarcseconds/year
B-V Index0.12
Radial Velocity-20.90000 ± 0.60 km/s
Iron Abundance-0.1800 ± 9.99 Fe/H
Eccentricity0.23020
Semi-Major Axis8718.0000000
Stellar Luminosity (Lsun)25.6100000

Companions (Multi-Star and Exoplanets) Facts


Exoplanet CountNone/Unaware

Estimated Calculated Facts


Radius (x the Sun)2.14
Effective Temperature8,298 Kelvin
Mass Compared to the Sun2.20

Sources and Links


SIMBAD SourceLink

Multi-Star System

The star has been identified as being a multi-star system, one in which there is at least one star in close orbit to another star or two or more stars orbiting a central point. The stars may be of equal mass, unequal mass where one star is stronger than the other or be in groups orbiting a central point which doesn't necessarily have to be a star. More information can be found on my dedicated multiple star systems page. The source of the info is Simbad. The file is dated 2000 so any differences between this and any other source will be down to the actual source from where the information came from.


Proper Motion mas/yr
H.D. IdB.D. IdStar CodeMagnitudeR.A.Dec.SpectrumColourYear
97603+21 2298.0A2.60000142.00000-135.00000A3White
B8.600001924
P12.100001879

Location of Zosma in Leo


Zosma Location in Leo

The map was generated using Night Vision, an awesome free application by Brian Simpson.

Leo Main Stars


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