The proximity of the world to its host star and the smaller size of the M-dwarf compared to a Sun-like star made it possible to discover KOI-4777.01, one of the tiniest ultra-short period worlds found.” Ultra-short period planets– planets with orbital periods less than one day– are very unusual,” stated Caleb Cañas, a graduate student in astronomy and astrophysics at Penn State and lead author of the paper. How long the dip in brightness lasts is a sign of the separation in between the prospect world and the host star, and indicator of if the world might be habitable. “Given how close this planet is to its host star, it is unlikely to be habitable, but we understood from the start that we would be able to discover about much more than just habitable worlds with the HPF.” With the accuracy of the HPF spectrograph we are able to verify that KOI-4777.01 is certainly a world by eliminating other possible sources of the signal, such as nearby stars or extra worlds,” stated Cañas.
NASAs Kepler objective discovered the around 10-hour transit of a Mars-sized exoplanet orbiting the M-dwarf star KOI-4777. The distance of the world to its host star and the smaller size of the M-dwarf compared to a Sun-like star made it possible to find KOI-4777.01, among the tiniest ultra-short duration worlds found. Researchers utilized the Penn State Habitable-zone Planet Finder, a high-precision huge spectrograph, to confirm the planetary nature of KOI-4777.01. The leading row shows an artists representation comparing the KOI-4777 system, with its M-dwarf host star and ultra-short duration Mars-sized world, to the Sun-Earth system on the exact same scale. The bottom row represents the actual range in between the Earth and Sun– around 160 times further away. Credit: Dani Zemba, Penn State
The planetary nature of a Mars-sized object orbiting extremely closely to an M-dwarf star has been verified utilizing the Penn State Habitable-zone Planet Finder (HPF). The planet, which was initially classified as an incorrect positive in an automated search of information collected by the Kepler space telescope, has to do with half the size of Earth and is so near to its host star that it orbits in less than 10 hours. If it were orbiting a star the size of our sun it would be skimming the stars corona– the aura of exceptionally hot plasma that extends out beyond the stars surface area! It is the tiniest planet with an ultra-short duration orbit known and might help astronomers understand how these uncommon planets form.
A paper explaining the discovery, by a group of researchers led by Penn State scientists, appears online and has been accepted for publication in The Astronomical Journal.
” Ultra-short duration worlds– worlds with orbital periods less than one day– are incredibly uncommon,” said Caleb Cañas, a graduate student in astronomy and astrophysics at Penn State and lead author of the paper. “Only a handful have been detected orbiting M-dwarf stars, which are small, cool stars a portion of the size and brightness of our sun. We dont yet understand precisely how these worlds form, so discoveries like these are essential for assisting us to constrain potential development scenarios.”
The Kepler space telescope searched for exoplanets– worlds beyond those in our planetary system– by observing stars in a big region of the Milky Way galaxy. It searched for small dips in the brightness of stars that could suggest that a portion of the stars light was being obstructed by a prospect world passing in front of the star throughout its orbit. The length of time the dip in brightness lasts is an indication of the separation between the prospect planet and the host star, and indication of if the world may be habitable. These dips in brightness, called transits, would then be vetted by an automatic system to determine prospective incorrect positives.
Kepler observed such a dip in the brightness of the M-dwarf star KOI-4777, but the dip was so quick that the automatic vetting originally suggested it to be an incorrect positive. A new statistical analysis method established by Eric Feigelson, Distinguished Senior Scholar and Professor of Astronomy and Astrophysics and of Statistics at Penn State, and his team of astrostatisticians, separately detected this planet at its correct duration in the Kepler dataset. Later on, a manual check of potential false positives in the Kepler data identified that the dip in brightness of KOI-4777 did in reality represent a possible planetary system with an orbital period of 0.412 days, or about 9.9 hours.
” We utilized the Habitable-zone Planet Finder, a high-precision astronomical spectrograph installed on the Hobby-Eberly Telescope at the McDonald Observatory in Texas to observe this system,” said Suvrath Mahadevan, teacher of astronomy and astrophysics at Penn State and an author of the paper. “Given how close this world is to its host star, it is unlikely to be habitable, but we understood from the start that we would have the ability to find out about much more than simply habitable worlds with the HPF. The precision of the HPF allowed us to statistically confirm the world, referred to as KOI-4777.01, and start to define its homes.”
Worlds orbiting stars exert a small gravitational pull that causes the star to wobble. This wobble outcomes in small shifts in the wavelength of light released by a star as a result of the Doppler result, similar to how the pitch of the siren on an ambulance changes as it speeds by you. HPF is developed to identify these slight shifts in wavelength in near-infrared light released by M-dwarf stars.
” With the precision of the HPF spectrograph we are able to verify that KOI-4777.01 is undoubtedly a planet by removing other possible sources of the signal, such as close-by stars or additional planets,” stated Cañas. Discovering additional such worlds will be essential for understanding how these rare planets form.”
In addition to Cañas, Feigelson, and Mahadevan, the research group includes William D. Cochran, Chad F. Bender, C. E. Harman, Ravi Kumar Kopparapu, Gabriel A. Caceres, Scott A. Diddams, Michael Endl, Eric B. Ford, Samuel Halverson, Fred Hearty, Sinclaire Jones, Shubham Kanodia, Andrea S.J. Lin, Andrew J. Metcalf, Andrew Monson, Joe P. Ninan, Lawrence W. Ramsey, Paul Robertson, Arpita Roy, Christian Schwab, and Guðmundur Stefánsson. This work was supported by NASA Headquarters under the NASA Earth and Space Science Fellowship Program and by the Alfred P. Sloan Foundations Minority Ph.D.
Program.
