We report the discovery and validation of four extrasolar planets hosted by the nearby , bright , Sun-like ( G3V ) star HD 108236 using data from the Transiting Exoplanet Survey Satellite ( TESS ) .
We present transit photometry , reconnaissance and precise Doppler spectroscopy as well as high-resolution imaging , to validate the planetary nature of the objects transiting HD 108236 , also known as the TESS Object of Interest ( TOI ) 1233 .
The innermost planet is a possibly-rocky super-Earth with a period of 3.79523 _ { -0.00044 } ^ { +0.00047 } days and has a radius of 1.586 \pm 0.098 R _ { \oplus } .
The outer planets are sub-Neptunes , with potential gaseous envelopes , having radii of 2.068 _ { -0.091 } ^ { +0.10 } R _ { \oplus } , 2.72 \pm 0.11 R _ { \oplus } , and 3.12 _ { -0.12 } ^ { +0.13 } R _ { \oplus } and periods of 6.20370 _ { -0.00052 } ^ { +0.00064 } days , 14.17555 _ { -0.0011 } ^ { +0.00099 } days , and 19.5917 _ { -0.0020 } ^ { +0.0022 } days , respectively .
With V and K _ { s } magnitudes of 9.2 and 7.6 , respectively , the bright host star makes the transiting planets favorable targets for mass measurements and , potentially , for atmospheric characterization via transmission spectroscopy .
HD 108236 is the brightest Sun-like star in the visual ( V ) band known to host four or more transiting exoplanets .
The discovered planets span a broad range of planetary radii and equilibrium temperatures , and share a common history of insolation from a Sun-like star ( R _ { \star } = 0.888 \pm 0.017 R _ { \odot } , T _ { eff } = 5730 \pm 50 K ) , making HD 108236 an exciting , opportune cosmic laboratory for testing models of planet formation and evolution .