Chi Serpentis
A magnetic, chemically peculiar variable star in Serpens.
Chi Serpentis is a solitary star located in the Serpens Caput part of the equatorial constellation Serpens. It lies roughly 222 light-years from the Sun, based on a parallax of 14.84 milliarcseconds, and is just visible to the naked eye at an apparent magnitude of +5.30.
Though listed as a suspected spectroscopic binary in 1966, the star is now thought to be single. It is a chemically peculiar Ap star, with a spectrum showing abnormal amounts of manganese and europium. Chi Serpentis has about 2.11 times the Sun’s mass and 2.25 times its radius, and it shines with 26 times the Sun’s luminosity from a photosphere heated to 9,557 K. At an age of 212 million years, it rotates once every 1.6 days.
Classified as an Alpha2 Canum Venaticorum type variable star, its brightness varies by 0.03 magnitudes with a period of 1.5948 days. Spectral variations indicate patches of enhanced strontium, chromium, iron, titanium, and magnesium on its surface. The star also possesses a surface magnetic field, with an averaged quadratic field strength noted in the data.
- Apparent visual magnitude
- +5.30
- Distance from earth
- 222 light years
- Stellar classification
- Ap star (chemically peculiar, manganese and europium excess)
- Mass
- 2.11 solar masses
- Radius
- 2.25 solar radii
- Luminosity
- 26 solar luminosities
- Effective temperature
- 9,557 K
- Rotation period
- 1.6 days
- Variable star type
- Alpha2 Canum Venaticorum
- Magnitude variation
- 0.03
Lore & Background
Chi Serpentis was listed in 1966 as a suspected spectroscopic binary, but it is now believed to be single. It is classified as an Ap star, with a spectrum showing abnormal excesses of manganese and europium. The star's surface magnetic field has an averaged quadratic field strength, and the pattern of variation in its spectrum suggests regions of enhanced strontium, chromium, iron, titanium, and magnesium on its surface. Its brightness varies by 0.03 magnitudes with a period of 1.5948 days, consistent with its classification as an Alpha2 Canum Venaticorum variable. The star is spinning with a rotation period of 1.6 days, and at an age of 212 million years, it radiates 26 times the solar luminosity from a photosphere at 9,557 K.
Reader's Guide
Chi Serpentis is significant as a chemically peculiar Ap star that exhibits the characteristic variability of an Alpha2 Canum Venaticorum type. Its small magnitude variation of 0.03 over a period of 1.5948 days is tied to the star's rotation and the presence of a structured surface magnetic field. The spectrum reveals patches of enhanced strontium, chromium, iron, titanium, and magnesium, which are typical of such magnetic chemically peculiar stars. The star's classification as a suspected spectroscopic binary was later resolved in favor of a single star. Its brightness at magnitude +5.30 makes it faintly visible to the naked eye, and its distance of about 222 light years places it within the local stellar neighborhood. The star's legacy lies in its role as an example of how magnetic fields and chemical inhomogeneities can produce periodic photometric and spectroscopic variations, contributing to the understanding of stellar magnetism and diffusion processes in intermediate-mass stars.
Did You Know?
- Chi Serpentis varies in brightness by only 0.03 magnitudes.
- Its spectrum shows abnormal excesses of manganese and europium.
- The star has a rotation period of 1.6 days.
- It was once suspected to be a spectroscopic binary but is now believed to be single.
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