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The Pleiades


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According to the  archaeo-astronomer Guido Cossard, two groups of man-made cup markings carved on a pair of boulders found in the Italian Alps may represent the Pleiades star cluster.
The carvings were found near the Plan des Sorcières -  'The witches' plateau' - at Lillianes, in Val d'Aosta (Italy).
According to Mr Cossard, who made the discovery, the series of cup markings have the same shape as the famous star cluster, and it may represent 'the most ancient star map ever found'.

"Even the archaeo-astronomical orientation of the site is a confirmation, because it's clearly aligned to the rising point of the Pleiades" - Guido Cossard.

The first cup-marked boulder was located by Paolo Chiaberto, a colleague of Mr Cossard, while the second was identified during a survey in the same area. In fact, were Alessandro and Francesco, Cossard's sons, who discovered the second group of markings. On the boulders there is an additional cup mark, and it may represent the 7th Sister of the Pleiades, considered to be missing. Although the Pleiades are popularly termed the Seven Sisters, only six stars are easily visible to the naked eye, and a considerable mythology has grown up to account for the 'missing' Pleiad, since the times of Eratosthenes (276 BCE - 194 BCE). Additional details of the discovery will be presented in Lillianes City Council on January 17th at 9PM.

Source: ANSA

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20:00 UT, 25th December, 2007.

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HD 23514
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Small, rocky planets that could resemble Earth or Mars may be forming around one of the hundreds of stars in the Pleiades cluster, astronomers reported Wednesday.
The star, known as HD 23514, is surrounded by an extraordinary number of hot dust particles that could be the building blocks of planets.

This is the first clear evidence for planet formation in the Pleiades, and the results we are presenting may well be the first observational evidence that terrestrial planets like those in our solar system are quite common - Joseph Rhee of the University of California at Los Angeles, who led the study.


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Rocky terrestrial planets, perhaps like Earth, Mars or Venus, appear to be forming or to have recently formed around a star in the Pleiades ("seven sisters") star cluster, the result of "monster collisions" of planets or planetary embryos.
 Astronomers using the Gemini Observatory in Hawaii and the Spitzer Space Telescope report their findings in an upcoming issue of the Astrophysical Journal, the premier journal in astronomy.
 
"This is the first clear evidence for planet formation in the Pleiades, and the results we are presenting may well be the first observational evidence that terrestrial planets like those in our solar system are quite common" - Joseph Rhee, a UCLA postdoctoral scholar in astronomy and lead author of the research.
 
Although referred to as the "seven sisters," "the cluster actually contains some 1,400 stars" - co-author Inseok Song, a staff scientist at NASA's Spitzer Science Centre at the California Institute of Technology and a former astronomer with the Gemini Observatory.
 
Located about 400 light-years away, the Pleiades is one of the closest star clusters to Earth. One of the cluster's stars, known as HD 23514, which has a mass and luminosity a bit greater than those of the sun, is surrounded by an extraordinary number of hot dust particles.

"hundreds of thousands of times as much dust as around our sun. The dust must be the debris from a monster collision, a cosmic catastrophe" - Benjamin Zuckerman.
 
The astronomers analysed emissions from countless microscopic dust particles and concluded that the most likely explanation is that the particles are debris from the violent collision of planets or planetary embryos.

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The Pleiades

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Mars and the Pleiades

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Time: 2:30 GMT 14th August 2007
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Title: A wide deep infrared look at the Pleiades with UKIDSS: new constraints on the substellar binary fraction and the low mass IMF
Authors: N. Lodieu (1 and 2), P. D. Dobbie (3 and 2), N. R. Deacon (4), S. T. Hodgkin (5), N. C. Hambly (6), R. F. Jameson (2) ((1) IAC, Tenerife, (2) Leicester, UK, (3) AAO, Australia, (4) Radboud University Nijmegen, (5) IoA, Cambridge, UK, (6) SUPA, ROE, Edinburgh, UK)

We present the results of a deep wide-field near-infrared survey of 12 square degrees of the Pleiades conducted as part of the UKIDSS Deep Infrared Sky Survey (UKIDSS) Galactic Cluster Survey (GCS). We have extracted over 340 high probability proper motion members down to 0.03 solar masses using a combination of UKIDSS photometry and proper motion measurements obtained by cross-correlating the GCS with data from the Two Micron All Sky Survey (2MASS), the Isaac Newton (INT) and the Canada-France-Hawai'i (CFHT) telescopes. Additionally, we have unearthed 73 new candidate brown dwarf members on the basis of five band UKIDSS photometry alone. We have identified 23 substellar multiple system candidates out of 63 candidate brown dwarfs from the (Y-K,Y) and (J-K,J) colour-magnitude diagrams, yielding a binary frequency of 28-44% in the 0.075-0.030 Msun mass range. Our estimate is three times larger than the binary fractions reported from high-resolution imaging surveys of field ultracool dwarfs and Pleiades brown dwarfs. However, it is marginally consistent with our earlier ``peculiar'' photometric binary fraction of 50+/-10% presented in Pinfield et al. (2003), in good agreement with the 32-45% binary fraction derived from the recent Monte-Carlo simulations of Maxted & Jeffries (2005) and compatible with the 26+/-10% frequency recently estimated by Basri & Reiners (2006). A tentative estimate of the mass ratios from photometry alone seems to support the hypothesis that binary brown dwarfs tend to reside in near equal-mass ratio systems.

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Title: Proper motion L and T dwarf candidate members of the Pleiades
Authors: S.L.Casewell, P.D. Dobbie, S.T. Hodgkin, E. Moraux, R.F. Jameson, N.C. Hambly, J. Irwin, N Lodieu

We present the results of a deep optical-near-infrared multi-epoch survey covering 2.5 square degrees of the Pleiades open star cluster to search for new very-low-mass brown dwarf members. A significant (~ 5 year) epoch difference exists between the optical (CFH12k I-, Z-band) and near infrared (UKIRT WFCAM J-band) observations. We construct I,I-Z and Z,Z-J colour magnitude diagrams to select candidate cluster members. Proper motions are computed for all candidate members and compared to the background field objects to further refine the sample. We recover all known cluster members within the area of our survey. In addition, we have discovered 9 new candidate brown dwarf cluster members. The 7 faintest candidates have red Z-J colours and show blue near-infrared colours. These are consistent with being L and T-type Pleiads. Theoretical models predict their masses to be around 11 Jupiter masses.

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