Three Massive Planets Orbit Nearby Giant Star HD 33142

by johnsmith

An international team of astronomers, using the radial velocity (RV) method, has discovered a third planet in the planetary system HD 33142.

An artist’s impression of the HD 33142 planetary system, which is located 397 light-years away in the constellation of Lepus. Image credit:

An artist’s impression of the HD 33142 planetary system, which is located 397 light-years away in the constellation of Lepus. Image credit:

“Since the first detection of an exoplanet around a solar-type star in 1995, the number of confirmed exoplanets has increased rapidly to over 5,000,” said Dr. Trifon Trifonov, an astronomer at the Max-Planck-Institut fur Astronomie and Sofia University ‘St Kliment Ohridski,’ and his colleagues.

“The majority of these have been discovered using the transit method, followed by the RV method.”

“The RV technique is the best way to determine the orbital architecture of multi-planet systems, which is important to improve our understanding of planet formation and orbital evolution.”

The newly-discovered planet orbits HD 33142, an early K-giant star located 121.8 parsecs (397 light-years) away in the constellation of Lepus.

Also known as HIP 23844 and BD-14 1051, this star is at least 2.7 billion years old, about 4 times larger and 1.5 times more massive than the Sun.

“HD 33142 is most likely a giant star at the very beginning of the red giant phase, but it could also be at the end of the subgiant branch,” the astronomers said.

The star was already known to host two Jovian-mass planets: HD 33142b with an orbital period of 330 days and HD 33142c with an orbital period of 830 days.

Dr. Trifonov and co-authors found strong evidence for the presence of a Saturn-mass, short-period companion.

Named HD 33142d, the alien world is five times less massive than Jupiter and orbits the parent star once every 90 days.

“We find that HD 33142b, c & d are likely to be engulfed near the tip of the red giant branch phase due to tidal migration,” the researchers said.

HD 33142d was detected in the observational data from the High Resolution Echelle Spectrometer (HIRES) mounted on the KECK 10-m telescope on Mauna Kea, Hawaii, the Fiber-fed Extended Range Optical Spectrograph (FEROS) on the 2.2-m telescope at ESO’s La Silla Observatory and the High Accuracy Radial velocity Planet Searcher (HARPS) on the 3.6-m telescope at the same observatory.

“Our discovery shows that it is worthwhile to revisit already known planetary systems with sparsely sampled radial velocities, as more precise data over longer temporal baselines lead to more discoveries of individual planets as well as to a more complete picture of the planetary system in which they exist,” the authors concluded.

Their paper will be published in the Astronomical Journal.


Trifon Trifonov et al. 2022. A new third planet and the dynamical architecture of the HD 33142 planetary system. AJ, in press; arXiv: 2206.03899

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