Editing Aldebaran (section)

==Planetary system==
In 1993 radial velocity measurements of Aldebaran, [[Arcturus]] and [[Pollux (star)|Pollux]] showed that Aldebaran exhibited a long-period radial velocity oscillation, which could be interpreted as a [[substellar companion]]. The measurements for Aldebaran implied a companion with a minimum mass 11.4 times that of [[Jupiter]] in a 643-day orbit at a separation of {{convert|2.0|AU|Gm|abbr=on}} in a mildly [[Eccentricity (orbit)|eccentric]] orbit. However, all three stars surveyed showed similar oscillations yielding similar companion masses, and the authors concluded that the variation was likely to be intrinsic to the star rather than due to the gravitational effect of a companion.<ref name=Kgiants/>

In 2015 a study led by [[Artie P. Hatzes]] showed stable long-term evidence for both a planetary companion and stellar activity.<ref name=hatzes/> An [[asteroseismic]] analysis of the residuals to the planet fit has determined that Aldebaran&nbsp;b has a minimum mass of {{val|5.8|0.7}} [[Jupiter mass]]es, and that when the star was on the main sequence it would have given this planet Earth-like levels of illumination and therefore, potentially, temperature. This would have placed it and any of its moons in the [[habitable zone]].<ref name="Farr2018" /> However, a follow-up study in 2019 found that additional data weaken the evidence for a planetary companion.<ref name=Reichert2019/> A two-planet solution fits the data better but would be unstable; the more likely explanation is that the radial velocity variations are caused by intrinsic stellar oscillations that mimic a planetary companion, as observed in [[Gamma Draconis]]<ref name=Reichert2019/> and [[42 Draconis]].<ref name="DöllingerHartmann2021"/><ref name="Hatzes2025"/> Based on the 2019 study, some subsequent studies of planet candidates around giant stars consider Aldebaran b doubtful or disproven,<ref name="Spaeth2024"/><ref name="Spaeth2025"/> including a 2025 paper with Hatzes as the lead author.<ref name="Hatzes2025"/>

{{OrbitboxPlanet begin
| table_ref = <ref name=hatzes/>
| period_unit = day
}}
{{OrbitboxPlanet hypothetical
| exoplanet = b
| mass = {{val|5.8|0.7|p=≥}}
| semimajor = {{val|1.46|0.27}}
| period = {{val|628.96|0.9}}
| eccentricity = {{val|0.1|0.05}}
| status = dubious
}}
{{Orbitbox end}}