  This work combines spectroscopic and photometric data of the polluted white
dwarf WD0141-675 which has a now retracted astrometric super-Jupiter candidate
and investigates the most promising ways to confirm Gaia astrometric planetary
candidates and obtain follow-up data. Obtaining precise radial velocity
measurement for white dwarfs is challenging due to their intrinsic faint
magnitudes, lack of spectral absorption lines, and broad spectral features.
However, dedicated radial velocity campaigns are capable of confirming close in
giant exoplanets (a few M$_{\textrm{Jup}}$) around polluted white dwarfs, where
additional metal lines aid radial velocity measurements. Infrared emission from
these giant exoplanets is shown to be detectable with JWST MIRI and will
provide constraints on the formation of the planet. Using the initial Gaia
astrometric solution for WD0141-675 as a case study, if there were a planet
with a 33.65 d period or less with a nearly edge on orbit, 1) ground-based
radial velocity monitoring limits the mass to $<$ 15.4 M$_{\textrm{Jup}}$, and
2) space-based infrared photometry shows a lack of infrared excess and in a
cloud-free planetary cooling scenario, a sub-stellar companion would have to be
$<$ 16 M$_{\textrm{Jup}}$ and be older than 3.7 Gyr. These results demonstrate
how radial velocities and infrared photometry can probe the mass of the objects
producing some of the astrometric signals, and rule out parts of the brown
dwarf and planet mass parameter space. Therefore, combining astrometric data
with spectroscopic and photometric data is crucial to both confirm, and
characterise astrometric planet candidates around white dwarfs.
