A star in the constellation Serpens may be a close match for our own Sun. HD 143436 (also known as HIP 78399, from its listing in the Hipparcos survey) is an 8th magnitude star that’s 140 light years from Earth and visible with binoculars. According to a recent article on the star by astronomer Ken Croswell, both its spectral type and its absolute magnitude are closely similar to Sol, and the star appears to be equally hot, with a temperature of 5768 Kelvin vs. the Sun’s 5777 K. In terms of mass, HD 143436 is the Sun’s twin.
Finds like this are intriguing because they raise the possibility that similar stars have similar solar systems, within which may lurk a terrestrial world. No one knows whether this star has a planet like Earth around it — or any planets at all, for that matter — but we do know that the close stellar match calls for further work. Exactly how old HD 143436 is remains conjectural, with an uncertainty either way of 2.9 billion years. The star may be as old as the Sun, or considerably younger, with potential ramifications on the development of intelligent life on any planets around it.
The work on HD 143436 is by Jeremy King and Simon Schuler, both of Clemson University, and Ann Boesgaard at the University of Hawaii; their paper “Keck/HIRES Spectroscopy of Four Candidate Solar Twins,” which will be published in The Astronomical Journal in November, can be found online at the arXiv site. King and colleagues studied four solar twin candidates, two that turned out to be older and metal-poor compared to the Sun, one which is significantly older, and HD 143436 itself, which they say “…may be equivalent to the ‘closest ever solar twin.'”
The astronomers’ work points out that solar analogs like this one give us the ability to learn more about the evolution of planets. From the paper:
“…it has been suggested that solar-type stars may be subject to highly energetic superflare outbursts, perhaps induced by orbiting planets, that would have dramatic effects on atmospheres surrounding and lifeforms inhabiting orbiting planets. It also seems clear that the nominal non-stochastic gradual evolution of solar-type chromospheres has important implications for a diversity of planetary physics (in our own solar system and others): the structure and chemistry of planetary atmospheres, the water budget on Mars, and even the evolution of planetary surfaces; such issues are critical ones to understand in the development and evolution of life.”
Centauri Dreams‘ note: Serpens is actually a divided constellation, consisting of Serpens Caput (the Head of the Serpent, and the segment in which HD 143436 is found) and Serpens Cauda (the Tail of the Serpent). The two parts are divided by the constellation Ophiuchus (the Serpent Holder).
