Epsilon Crucis

Epsilon Crucis, Latinised from ε Crucis (abbreviated Epsilon Cru, ε Cru) and also known as Ginan /ˈɡiːnən/,^[9] is a single,^[10] orange-hued star in the southern constellation of Crux. Measurements made by the Gaia spacecraft showed an annual parallax shift of 14.2 mas,^[1] which provides a distance estimate of about 230 light-years. The star can be seen with the naked eye, having an apparent visual magnitude of 3.58.^[2] It is moving closer to the Sun with a radial velocity of −4.60 km/s.^[6]

ε Crucis

Location of ε Crucis (circled)
Observation data Epoch J2000.0      Equinox J2000.0
Constellation	Crux
Right ascension	12h 21m 21.608s[1]
Declination	−60° 24′ 04.13″[1]
Apparent magnitude (V)	3.58[2]
Characteristics
Spectral type	K3 III[3]
Apparent magnitude (B)	4.98±0.01[4]
Apparent magnitude (G)	3.1[4]
Apparent magnitude (J)	1.226±0.274[4]
U−B color index	+1.63[2]
B−V color index	+1.42[2]
Variable type	suspected[5]
Astrometry
Radial velocity (Rv)	−4.60[6] km/s
Proper motion (μ)	RA: −171.223 mas/yr[1] Dec.: 91.795 mas/yr[1]
Parallax (π)	14.2±0.1 mas[1]
Distance	230 ± 2 ly (70.4 ± 0.5 pc)[1]
Absolute magnitude (MV)	−0.63±0.09[7]
Details
Mass	(1.4 – 1.5)±0.2[8] M☉
Radius	31±2[8] R☉
Luminosity	282[8] L☉
Surface gravity (log g)	1.91[6] cgs
Temperature	4,210±125[8] K
Metallicity [Fe/H]	−0.03[8] dex
Rotational velocity (v sin i)	3.14[6] km/s
Age	2.17[6] Gyr
Other designations
Ginan, ε Cru, NSV 5568, CD−59°4221, FK5 2989, HD 107446, HIP 60260, HR 4700, SAO 251862[4]
Database references
SIMBAD	data

This is a giant star of type K with a stellar classification of K3III,^[3] indicating that it has exhausted the hydrogen at its core and evolved away from the main sequence. It is about two billion years old^[6] with 1.4–1.5 times the mass of the Sun and has expanded to 31 times the Sun's radius. The star is shining with around 282 times the Sun's luminosity from its enlarged photosphere at an effective temperature of 4,210 K.^[8]

Nomenclature

ε Crucis (Latinised to Epsilon Crucis) is the star's Bayer designation.

The star bore the traditional name Ginan in the culture of the Wardaman people of the Northern Territory of Australia,^[11] which refers to a dilly bag - the "Bag of Songs."^[12] In 2016, the IAU organized a Working Group on Star Names (WGSN)^[13] to catalog and standardize proper names for stars. The WGSN approved the name Ginan for Epsilon Crucis on 19 November 2017 and it is now so included in the List of IAU-approved Star Names.^[9] According to the WGSN's 2023 annual report, this naming was in error: Ginan is actually the Wardaman name for Alpha Crucis; the name for Epsilon Crucis is Wuja, "fire". Since the name Ginan was already approved, it will not be changed.^[14] The current IAU Catalog of Star Names (as of April 2025^[update]) does not mention this error.^[15]

It is also sometimes called Intrometida (intrusive) in Portuguese.^[16]

In culture

Ginan is represented on the national flags of Australia, Papua New Guinea and Samoa. It is also featured in the flag of Brazil, along with 26 other stars, each of which represents a state. It represents the State of Espírito Santo.^[17]

Left: The bright blue star on the right centre of this image is Epsilon Crucis. The colours used in this image represent specific wavelengths of infrared light. Blue represents light emitted at 3.4 and 4.6 micrometres. Right: Crux (Southern Cross) from Hobart, Tasmania.