XO-5b

Lore & Background

XO-5b was the fifth hot Jupiter transiting planet discovered by the XO Project. It was identified as a possible candidate from two seasons of observations: November 2003 to March 2004 and November 2004 to March 2005. Follow-up photometry was provided by a collaboration of professional and amateur astronomers, producing better-quality light curves to guide photometric and spectroscopic follow-up. To confirm its planetary nature, radial velocity observations of XO-5 were made with the high-resolution spectrograph on the 11-meter Hobby–Eberly Telescope at McDonald Observatory. Commencing on December 7, 2007, a total of ten radial velocity measurements confirmed XO-5b's status as a planet. The planet orbits very close to its G-type parent star, typical for transiting planets, taking only 4.188 days to complete an orbit at a distance of 0.0488 AU.

Reader's Guide

XO-5b's significance lies in its role as the fifth hot Jupiter discovered by the XO Project, demonstrating the effectiveness of the transit method for finding close-in giant planets. Its independent discovery by the HATNet Project underscores the collaborative nature of exoplanet detection and the reliability of transit surveys. The planet's mass and radius, slightly larger than Jupiter, place it in the typical hot Jupiter category, contributing to the statistical understanding of such planets. The naming of XO-5b as Makropulos, selected by the Czech Republic during the NameExoWorlds campaign on the 100th anniversary of the IAU, links the exoplanet to Karel Čapek's play Věc Makropulos (The Makropulos Affair), adding cultural resonance. The follow-up observations involving amateur astronomers highlight the growing role of citizen science in exoplanet research. The radial velocity measurements from the Hobby–Eberly Telescope provided the mass confirmation necessary to distinguish the object from other astrophysical phenomena, cementing its legacy as a well-characterized transiting planet.

Did You Know?

• XO-5b is also known as Makropulos, a name from Karel Čapek's play Věc Makropulos.
• It was independently discovered by the XO Telescope and the HATNet Project.
• The planet orbits its star every 4.188 days at a distance of 0.0488 AU.
• Radial velocity confirmation used the Hobby–Eberly Telescope at McDonald Observatory.