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Ursids

From Wikipedia, the free encyclopedia
Ursids (URS)
Ursa Minor with the radiant of the Ursids marked in red
Parent body8P/Tuttle[1]
Radiant
ConstellationUrsa Minor (near Kochab)
Right ascension14h 36m [2]
Declination+75.3°[2] (Northern Hemisphere)
Properties
Occurs duringDecember 17 – December 26[1]
Date of peakDecember 22[1]
Velocity33[2] km/s
Zenithal hourly rate10[1]
See also: List of meteor showers

The Ursid (URS) meteor activity begins annually around December 17 and runs for over a week, until the 25th or 26th. This meteor shower is named for its radiant point, which is located near the star Beta Ursae Minoris (Kochab) in the constellation Ursa Minor.

History

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The Ursids were probably discovered by William F. Denning, who observed them for several years around the start of the 20th century.[1] While there were sporadic observations after, the first coordinated studies of the shower didn't begin until Dr. A. Bečvář observed an outburst of 169 per hour in 1945.[1] Further observations in the 1970s and ongoing to current have established a relationship with comet 8P/Tuttle.[1] Peter Jenniskens and Esko Lyytinen discovered that outbursts could happen when comet Tuttle was at aphelion because some meteoroids get trapped in the 7/6 orbital resonance with Jupiter.

Technical information

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Earlier observations described an average radiant of RA=217°, DEC=76°,[1] with maximum occurring at a solar longitude of 270.66 deg (about December 22), with the duration being established as December 17–24.

The Ursids have a particularly narrow stream, prompting veteran meteor observer, Norman W. McLeod, III (Florida) to comment that the Ursids "must be a compact stream like the Quadrantids. You have to be within 12 hours of maximum to see much."[1]

References

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  1. ^ a b c d e f g h i Gary W. Kronk. "Observing the Ursids". Meteor Showers Online. Archived from the original on 2013-07-24. Retrieved 2012-11-17.
  2. ^ a b c IMO Meteor Shower Calendar: Ursids (URS)
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