OGLE-TR-111b
A hot Jupiter missing link between transiting planet types.
OGLE-TR-111b is a planet located about 5,000 light-years away in the constellation Carina. It is the only confirmed planet circling the star OGLE-TR-111, although there may be a second planet. The planet was first spotted in 2002 by the Optical Gravitational Lensing Experiment (OGLE), which noticed the star's light dimming slightly every four days—a sign that something was passing in front of it. However, without a mass measurement, astronomers couldn't tell if it was a true planet, a low-mass red dwarf, or something else. Radial velocity measurements in 2004 confirmed it is a planet. OGLE-TR-111b is likely much like other hot Jupiters. It has about half the mass of Jupiter and orbits its star at less than one-twentieth the distance from Earth to the Sun. Its mass and orbital distance are similar to those of HD 209458 b (Osiris), the first transiting planet discovered. But unlike Osiris, OGLE-TR-111b has a radius about the same as Jupiter's, which is typical of other transiting planets found by OGLE. Those other OGLE planets tend to be more massive and orbit even closer than typical hot Jupiters, making this planet an important "missing link" between different types of transiting planets.
Quick Facts
- Discoverer
- Udalski et al.
- Discovery Site
- Poland
- Discovered
- 2002
- Discovery Method
- Transit and Doppler
- Apsis
- astron
- Semimajor
- 0.047 ±
- Eccentricity
- 0
- Period
- 4.01610 d
- Inclination
- 88.1
- Time Periastron
- 2,452,330.44867
- Star
- OGLE-TR-111
- Density
- 700 kg/m3
Facts from the source article.
Lore & Background
In 2002, the Optical Gravitational Lensing Experiment (OGLE) survey detected that the light from the star OGLE-TR-111 periodically dimmed very slightly every 4 days, indicating a planet-sized body transiting the star. However, since the mass of the object had not been measured, it was not clear that it was a true planet, a low-mass red dwarf, or something else. In 2004, radial velocity measurements showed unambiguously that the transiting body is indeed a planet.
The planet is probably very similar to other hot Jupiters orbiting nearby stars. OGLE-TR-111b has similar mass and orbital distance as the first transiting planet, HD 209458 b (Osiris). Unlike that planet, however, OGLE-TR-111b has a radius comparable to Jupiter, which is typical of other transiting planets detected by OGLE. Those other OGLE-detected planets tend to be more massive and orbit even closer than typical hot Jupiters, making OGLE-TR-111b an important 'missing link' between the different types of transiting planets.
Reader's Guide
OGLE-TR-111b holds significance as a transitional object in the study of transiting exoplanets. Its mass, about half that of Jupiter, and its orbital distance, less than 1/20th of an astronomical unit, place it in a category similar to the first known transiting planet, HD 209458 b. However, its radius, comparable to Jupiter, aligns it with the typical OGLE-detected transiting planets, which are generally more massive and orbit even closer than standard hot Jupiters. This combination of characteristics makes OGLE-TR-111b a 'missing link' that bridges the properties of early transiting discoveries and the bulk of OGLE's planetary finds. The planet's confirmation in 2004 via radial velocity measurements resolved earlier ambiguity about its nature, establishing it as a true planet rather than a low-mass red dwarf or other stellar object. Its existence helps refine models of planetary formation and migration, particularly for hot Jupiters in short-period orbits. As the only confirmed planet around OGLE-TR-111, with a possible second planet still plausible, it remains a key object for understanding the diversity of transiting exoplanets and the OGLE survey's contributions to the field.
Did You Know?
- OGLE-TR-111b is approximately 5,000 light-years away in the constellation Carina.
- Its mass is about half that of Jupiter, and its radius is comparable to Jupiter.
- The planet orbits its star every 4 days at a distance less than 1/20th that of Earth from the Sun.
- It was confirmed as a planet in 2004 via radial velocity measurements, after initial detection by the OGLE survey in 2002.
Frequently Asked Questions
What is OGLE-TR-111b?
OGLE-TR-111b is a gas giant orbiting the star OGLE-TR-111 roughly 5,000 light-years away in the constellation Carina. It is the only confirmed world around that star, although a second companion has been hinted at.
How was OGLE-TR-111b discovered?
The Optical Gravitational Lensing Experiment first flagged the system in 2002 when it noticed the host star dimming slightly on a four-day cycle, indicating something was transiting in front of it. Radial velocity follow-up in 2004 then pinned down a planetary mass, ruling out a low-mass red dwarf.
What are OGLE-TR-111b's key physical stats?
The planet has a radius close to Jupiter's but only about half Jupiter's mass, making it a puffy, low-density world. It races around its star in just four days at a distance less than one-twentieth of Earth's orbital radius.
Why do astronomers call OGLE-TR-111b a 'missing link'?
Its combination of a Jupiter-like size with only half the mass places it in a transitional zone between the denser, smaller transiting planets and the more inflated hot Jupiters. That makes it a useful reference point for understanding how transiting planet populations connect to one another.
Is OGLE-TR-111b a hot Jupiter?
Yes—it is classified as a hot Jupiter given its extremely short four-day orbit so close to its host star. What sets it apart is its unusually low density for the category, which is exactly why it fills a gap in the broader transiting-planet family.
More in Transiting Exoplanets, Part 5 1-24
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