Universe Guide

Eta Serpentis (58 Serpentis) Star Facts

Eta Serpentis Facts

Eta Serpentis's Alternative Names

Eta Serpentis (Eta Ser) 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 HR6869. HIP89962 is the reference name for the star in the Hipparcos Star Catalogue. The Id of the star in the Henry Draper catalogue is HD168723. The Gliese ID of the star is GL 711. The star was part of the original catalogue devised by German Astronomer Wilheim Gliese of stars located within 20 parsecs of Earth. Star Names

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 58 Serpentis. The Flamsteed name can be shortened to 58 Ser.

The Gould star designation is one that was designed by American astronomer, Benjamin Apthorp Gould. Gould stars are predominantly in the Southern and Equatorial constellations but do appear in northern constellations such as Bootes and Orion. The star has the designation 34 Cau G. Serpentis. There are no stars with a Gould designation in Ursa Major for example.

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-02 4599.

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

Location of Eta Serpentis

The location of the subgiant 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 Eta Serpentis, the location is 18h 21m 18.92 and -02° 53` 49.6 .

Radial Velocity and Proper Motion of Eta Serpentis

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 -701.42 ± 0.12 milliarcseconds/year towards the north and -547.75 ± 0.18 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 9.83 km/s with an error of about 0.09 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.

Eta Serpentis 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 20.19 that I have given is based on the value in the Simbad Hipparcos Extended Catalogue at the University of Strasbourg from 2012.

Physical Properties (Colour, Temperature) of Eta Serpentis

Eta Serpentis Colour and Temperature

Eta Serpentis has a spectral type of K0III-IV. This means the star is a orange to red subgiant star.

The star's effective temperature is 4,975 Kelvin which is cooler than our own Sun's effective Temperature which is 5,777 Kelvin

Eta Serpentis Radius

Radius has been calculated as being 5.40 times bigger than the Sun. The Sun's radius is 695,800km, therefore the star's radius is an estimated 3,758,431.09.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 5.28. The figure is derived at by using the formula from SDSS and has been known to produce widely incorrect figures. The star's 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.

Eta Serpentis Apparent and Absolute Magnitudes

Eta Serpentis has an apparent magnitude of 3.23 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 1.84 If you used the 2007 Parallax value, you would get an absolute magnitude of 1.89. 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 Eta Serpentis

Using the original Hipparcos data that was released in 1997, the parallax to the star was given as 52.81 which gave the calculated distance to Eta Serpentis as 61.76 light years away from Earth or 18.94 parsecs. If you want that in miles, it is 41,417,283,007.

In 2007, Hipparcos data was revised with a new parallax of 53.93 which put Eta Serpentis at a distance of 60.48 light years or 18.54 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 3,824,122.86 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 7,384.00 Parsecs or 24,083.90 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 Eta Serpentis

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)
Airbus A38073655,107,192.56
Speed of Sound (Mach 1)767.26952,861,374.20
Concorde (Mach 2)1,534.5426,430,652.65
New Horizons Probe33,0001,229,057.39
Speed of Light670,616,629.0060.48

Meteor Showers Radiating from near Eta Serpentis

The eta Serpentids Meteor Shower radiants from a point near this star. The meteor shower runs typically between with a peak date of 24th August. The speed of a meteor in the shower is 9 Km/s.

The June Scutids (Eta Serpentids) Meteor Shower radiants from a point near this star. The meteor shower runs typically between 2 Jun- 29 Jul with a peak date of 27-Jun. The amount of meteors predicted to be seen per hour (Zenith Hourly Rate) is .

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 Eta Serpentis Facts and Figures

Visual Facts

Primary / Proper / Traditional NameEta Serpentis
Alternative NamesEta Ser, HD 168723, HIP 89962, HR 6869, 34 Cau G. Serpentis, 58 Serpentis, 58 Ser, BD-02 4599, Gliese 711
Spectral TypeK0III-IV
Constellation's Main StarYes
Multiple Star SystemYes
Star TypeSubgiant Star
ColourOrange to Red
GalaxyMilky Way
Absolute Magnitude 1.84 / 1.89
Visual / Apparent Magnitude3.23
Naked Eye VisibleYes - Magnitudes
Right Ascension (R.A.)18h 21m 18.92
Declination (Dec.)-02° 53` 49.6
Galactic Latitude5.36 degrees
Galactic Longitude26.90 degrees
1997 Distance from Earth52.81 Parallax (milliarcseconds)
 61.76 Light Years
 18.94 Parsecs
2007 Distance from Earth53.93 Parallax (milliarcseconds)
 60.48 Light Years
 18.54 Parsecs
 3,824,122.86 Astronomical Units
Galacto-Centric Distance24,083.90 Light Years / 7,384.00 Parsecs
Proper Motion Dec.-701.42 ± 0.12 milliarcseconds/year
Proper Motion RA.-547.75 ± 0.18 milliarcseconds/year
B-V Index0.94
Radial Velocity9.83 ± 0.09 km/s
Iron Abundance-0.18 ± 9.99 Fe/H
Semi-Major Axis4904.00
Stellar Luminosity (Lsun)20.19

Companions (Multi-Star and Exoplanets) Facts

Exoplanet CountNone/Unaware

Estimated Calculated Facts

Radius (x the Sun)5.28
Effective Temperature4,968 Kelvin

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
168723-02 4599.0A3.40000-554.00000-697.00000K0Orange

Serpens Main Stars

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