To date, no solar twin with an exact match to that of the Sun has been found. However, there are some stars that come very close to being identical, and thus considered solar twins by the astronomical community. An exact solar twin would be a G2V star with a 5,778K temperature, be 4.6 billion years old, with solar metallicity, and a 0.1% solar luminosity variation.[5] Stars with an age of 4.6 billion years, such as the Sun, are at the most stable state. Proper metallicity and size are also very important to low luminosity variation.[6][7][8]
^Gray, R. O.; Corbally, C. J.; Garrison, R. F.; McFadden, M. T.; Bubar, E. J.; McGahee, C. E.; O'Donoghue, A. A.; Knox, E. R. (2006). "Contributions to the Nearby Stars (NStars) Project: Spectroscopy of Stars Earlier than M0 within 40 pc-The Southern Sample". The Astronomical Journal. 132 (1): 161–170. arXiv:astro-ph/0603770. Bibcode:2006AJ....132..161G. doi:10.1086/504637. S2CID119476992.
^Porto de Mello, G. F.; da Silva, R.; da Silva, L. & de Nader, R. V. (March 2014). "A photometric and spectroscopic survey of solar twin stars within 50 parsecs of the Sun; I. Atmospheric parameters and color similarity to the Sun". Astronomy and Astrophysics. 563: A52. arXiv:1312.7571. Bibcode:2014A&A...563A..52P. doi:10.1051/0004-6361/201322277. S2CID119111150.