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Kepler Confirms 100+ New Exoplanets (phys.org)
schwit1 writes: Astronomers have confirmed another 100 of Kepler's more than 3,000 candidate exoplanets. Phys.org reports: "One of the most interesting set of planets discovered in this study is a system of four potentially rocky planets, between 20 and 50 percent larger than Earth, orbiting a star less than half the size and with less light output than the Sun. Their orbital periods range from five-and-a-half to 24 days, and two of them may experience radiation levels from their star comparable to those on Earth. Despite their tight orbits -- closer than Mercury's orbit around the sun -- the possibility that life could arise on a planet around such a star cannot be ruled out, according to Crossfield." Because the host star as well as many of these other confirmed exoplanets are red dwarf stars, the possibility of life is reduced because the star and its system is likely to have a less rich mix of elements compared to our yellow G-type Sun. In May, Kepler added a record 1,284 confirmed planets, nine of which orbit in their sun's habitable zone.
Planets, within the habitable zone, for red dwarfs would likely be tidally locked, as the distance then is actually a function of the color (as a proxy for temperature) and size of the star.
Earth is far enough away to never be tidal locked.
Earth has a tidal locking timescale of ~30 billion years, although a resonance is an alternative outcome. That is too long for the given age of the universe, but considering that scales roughly like the sixth power of distance, you don't have to move much closer to shorten the timescale. Move a lot closer, and you make resonances, like Mercury, much harder too.