Star in the constellation Eridanus
! style="text-align: center; background-color: #FFFFC0;" colspan="2" | Observation dataEpoch J2000      Equinox J2000
! style="text-align:left" | Constellation
! style="text-align:left" | Right ascension
! style="text-align:left" | Declination
! style="text-align:left" | Apparent magnitude (V)
! style="background-color: #FFFFC0; text-align: center;" colspan="2"| Characteristics
! style="text-align:left" | Evolutionary stage
! style="text-align:left" | Spectral type
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WASP-78, is a single F-type main-sequence star about 2350 light-years away. It is likely to be younger than the Sun at 3.4 billion years. WASP-78 is depleted in heavy elements, having a 45% concentration of iron compared to the Sun.
Planetary system.
In 2012 a transiting hot Jupiter planet b was detected on a circular orbit. The planetary equilibrium temperature is 2350±80 K, while the nightside temperature measured in 2019 is 2200±41 K. The dayside planetary temperature measured in 2020 is 2560±130 K.
A survey in 2016 measured a Rossiter-McLaughlin effect and found the planetary orbit is well aligned with the equatorial plane of the star, misalignment equal to −6.4±5.9° The planet cannot have formed in its current orbit and has likely undergone in the past a migration from the initial highly eccentric orbit.
! align=center| Companion
! align=center| Mass
! align=center| Semimajor axis
! align=center| Orbital period
! align=center| Eccentricity
! align=center| Inclination
! align=center| Radius
References.
 ;templatestyles src="Reflist/styles.css" / ;
 ;indicator name="01-sky-coordinates" ; ;templatestyles src="Template:Sky/styles.css" / ;Coordinates: &amp;de=&amp;zoom=&amp;show_grid=1&amp;show_constellation_lines=1&amp;show_constellation_boundaries=1&amp;show_const_names=1&amp;show_galaxies=1&amp;img_source=IMG_all 04h 15m 01.5044s, −22° 06′ 59.1039″ ;/indicator ;