HD 172555

HD 172555

An artist's conception of a body about the size of the Moon slamming into a body the size of Mercury. As the bodies hit each other at speeds exceeding 10 km per second (about 22,400 mph), a huge flash of light is emitted, and their rocky surfaces are vaporized and melted, spraying hot matter everywhere.
Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Pavo
Right ascension 18h 45m 26.9011s
Declination −64° 52′ 16.533″
Apparent magnitude (V) 4.8
Characteristics
Spectral type A5 IV/V,[1] A7V (Hipparcos 2007 Catalogue)
Astrometry
Distance95.34 ± 1.86 ly
(29.23 ± 0.57 pc)
Details
Mass2.0[2] M☉
Luminosity9.5[2] L☉
Temperature8,000[1] K
Rotational velocity (v sin i)175[3] km/s
Age~12,[2] ~20 [4] Myr
Other designations
CPD−64° 3948, FK5 3489, GC 25604, HIP 92024, SAO 254358
Database references
SIMBADdata

HD 172555 is a white-hot Type A7V star located relatively close by, 95 light years from Earth in the direction of the constellation Pavo.[5] Spectrographic evidence indicates a relatively recent collision between two planet-sized bodies that destroyed the smaller of the two, which had been at least the size of the Moon, and severely damaged the larger one, which was at least the size of Mercury. Evidence of the collision was detected by NASA's Spitzer Space Telescope. [6] [2]

  1. ^ a b Cite error: The named reference apj663_1_365 was invoked but never defined (see the help page).
  2. ^ a b c d Cite error: The named reference Lisse2009 was invoked but never defined (see the help page).
  3. ^ Cite error: The named reference apj546_1_352 was invoked but never defined (see the help page).
  4. ^ Cite error: The named reference Mamajek2014 was invoked but never defined (see the help page).
  5. ^ When worlds collide Archived 2009-08-13 at the Wayback Machine Discover magazine, August 10, 2009
  6. ^ Hot Dust Evinces a Violent Planetary Collision Around a Nearby Star[permanent dead link] Physics Today, October 2009