The Jupiter-sized worlds whiz around the stars so fast that their year lasts less than an Earth day.
Astronomers used the Hubble Space Telescope to detect the "ultra-short period" planets (USPPs) by spotting the dip in a star's brightness caused by an object passing in front of it.
The planets were in a faint crowded star field towards the "galactic bulge" at the centre of the Milky Way.
Back up measurements based on the "wobble" a star is given by gravitational interaction with an orbiting planet supported the observations.
The five were among 16 candidates for new planets found by the SWEEP (Sagittarius Window Eclipsing Extrasolar Planet Search) survey.
Each of them orbited smallish stars with a mass roughly 0.88 that of the Sun.
Scientists believe planets so close to heavier, more luminous stars would be boiled away.
The findings were reported in the British weekly science journal Nature.
The astronomers, led by Dr Kailash Sahu, from the Space
Telescope Science Institute in Baltimore, Maryland, US, wrote:
"Five candidates have orbital periods below one day, constituting a new class of ultra-short period planets, which occur only around stars of less than 0.88Msun. This indicates that those orbiting very close to more luminous stars might be evaporatively destroyed, or that Jovian planets around stars of lower mass migrate to smaller radii."
They believe that any planets which orbited at such a close distance to brighter, hotter stars would be destroyed by solar radiation.
Large, Jupiter-sized planets are also being spotted at these remarkably close orbits because the star, being of low mass, exerts a relatively low gravitational pull.
The finding opens up a new area of investigation for space scientists probing extrasolar planets -- planets that orbit stars other than our own.
Astronomers have spotted 202 extrasolar planets since the first was found in October 1995. Most have been found by the "wobble" method of detection.
Looking for planets by spotting evidence of their "transits" across the face of stars is a relatively new technique.