25 Sextantis

Lore & Background

The star was first discovered to be variable in 1980 by French astronomers P. Renson and J. Manfroid, who observed a 4.37-day period and a fluctuation of 0.03 magnitudes in optical light. The following year, it was confirmed as variable and given the designation SS Sextantis. J. Manfroid and G. Mathys later refined the period to 4.39 days, though with larger uncertainty. In 1993, D. A. Bohlender and colleagues measured the star's magnetic field, finding it varied between 650 and 1,200 gauss, though with some uncertainty; subsequent observations provided a much wider range between 1 and -1,000 gauss. 25 Sextantis has a stellar classification of B9pSi(CrSr), indicating it is a Bp star with enhanced silicon, chromium, and strontium in its spectrum. It has 2.48 times the mass of the Sun and 2.22 times the radius of the Sun, radiating 45.7 times the solar luminosity at an effective temperature that gives it a bluish-white hue. It is metal deficient, with an iron abundance 64.6% of the Sun's, and is estimated to be 309 million years old, having completed 56% of its main sequence lifetime. Like many chemically peculiar stars, it spins modestly.

Reader's Guide

25 Sextantis holds significance as a chemically peculiar Bp star whose variability and magnetic field have been studied over several decades. Its discovery as a variable in 1980 by Renson and Manfroid, followed by confirmation and designation as SS Sextantis, established it as a target for stellar astrophysics. The refinement of its rotation period from 4.37 to 4.39 days, albeit with increased uncertainty, illustrates the iterative nature of period determination. The measurement of its magnetic field, initially reported to vary between 650 and 1,200 gauss with some uncertainty, and later found to span a much wider range from 1 to -1,000 gauss, highlights the complexity of magnetic activity in such stars. As a B9pSi(CrSr) star, it contributes to the understanding of chemical peculiarity and slow rotation in intermediate-mass stars. Its estimated age of 309 million years and completion of 56% of its main sequence lifetime provide context for its evolutionary stage. The star's legacy lies in its role as a well-characterized example of a magnetic, chemically peculiar variable, offering insights into stellar magnetism, rotation, and atmospheric abundance anomalies.

Did You Know?

• Its rotation period was initially measured at 4.37 days, later refined to 4.39 days with larger uncertainty.
• The star's magnetic field varies between 650 and 1,200 gauss, though subsequent observations show a wider range of 1 to -1,000 gauss.
• It has a spectral type of B9pSi(CrSr), indicating enhanced silicon, chromium, and strontium.