0000013883 00000 n They found evidence of a planet orbiting the star with a period of about seven years. The sequence number of Epsilon Eridani in the constellation Eridanus was 10, and it was designated Quae omnes quatuor antecedit, Latin for 'which precedes all four'; the meaning is the same as Ptolemy's description. Norse gods don't live on Mt. The constellation Eridanus was named by Ptolemy (Ancient Greek: Ποταμού, River), and Epsilon Eridani was listed as its thirteenth star. [note 3][49] In 1847, a new edition of Lalande's catalogue was published by Francis Baily, containing the majority of its observations, in which the stars were numbered in order of right ascension. At a distance of 10.5 light-years (3.2 parsecs) from the Sun, it has an apparent magnitude of 3.73. [80] Epsilon Eridani is located in the northern part of the constellation Eridanus, about 3° east of the slightly brighter star Delta Eridani. [76] The system has continued to be among the targets of such proposals, such as Project Icarus in 2011. [70] Despite this lack of success, Epsilon Eridani made its way into science fiction literature and television shows for many years following news of Drake's initial experiment. [6] Measurement of this rotational modulation suggests that its equatorial region rotates with an average period of 11.2 days,[16] which is less than half of the rotation period of the Sun. [49][50] Also in 1801 it was included in the catalogue of Johann Bode, in which about 17,000 stars were grouped into 102 constellations and numbered (Epsilon Eridani got the number 159 in the constellation Eridanus). 0000009606 00000 n [54], Based on observations between 1800 and 1880, Epsilon Eridani was found to have a large proper motion across the celestial sphere, which was estimated at three arcseconds per year (angular velocity). Among the known nearby stars, it was listed with the 14 stars that were thought most likely to have a habitable planet. [46][47][48], In 1801 Epsilon Eridani was included in Histoire Céleste Française, Joseph Jérôme Lefrançois de Lalande's catalogue of about 50,000 stars, based on his observations of 1791–1800, in which observations are arranged in time order. [23][125] The orbital radius where the UV flux matches that on the early Earth lies at just under 0.5 AU. [26][114], In an alternative scenario, the exozodiacal dust may be generated in an outer belt that is orbiting between 55 and 90 AU from Epsilon Eridani and has an assumed mass of 10−3 times the mass of Earth. [94][95] Epsilon Eridani's corona appears larger and hotter than the Sun's, with a temperature of 3.4 × 106 K, measured from observation of the corona's ultraviolet and X-ray emission. 367 0 obj <> endobj designation system for extrasolar planets, Royal Observatory at the Cape of Good Hope, Doppler shift of the star along the line of sight, science fiction literature and television shows, Centre de Données astronomiques de Strasbourg, "The IRSA 2MASS all-sky point source catalog, NASA/IPAC infrared science archive", Monthly Notices of the Royal Astronomical Society, Harvard-Smithsonian Center for Astrophysics, "Bulletin of the IAU Working Group on Star Names, No. )[36], Epsilon Eridani has been known to astronomers since at least the 2nd century AD, when Claudius Ptolemy (a Greek astronomer from Alexandria, Egypt) included it in his catalogue of more than a thousand stars. [68][117], Infrared observation has shown there are no bodies of three or more Jupiter masses in this system, out to at least a distance of 500 AU from the host star. [16], The high levels of chromospheric activity, strong magnetic field, and relatively fast rotation rate of Epsilon Eridani are characteristic of a young star. trailer It has several other catalogue designations. startxref It gives a brief definition of each concept and its relationships. [53] In 1918 Epsilon Eridani appeared in the Henry Draper Catalogue with the designation HD 22049 and a preliminary spectral classification of K0. This process involves recording the position of Epsilon Eridani as Earth moves around the Sun, which allows a star's distance to be estimated. �����t�(�N05֚����*�9�o��X�����W���N������1_�Q�R��NۮP��(>�z��� ��9"��S ��E��q�կ���`��EO�jϠm�G+�J�R�t�6�t����K$6����=���d��V�y��.�y� �^13��cˁ��WRzξ�� �~�O����3�B�?E"�N�,��(��2�����&8ݕ�z�E�贌�e�t:�Ց����뵊�#�ٹ���$>M�,�y����WĜA{� �"C�0̴�7L0Sµ]������n��ҥ��ȼa �b��X�� �[ �I�Kn��u�>>���42�� �J`4d�DB1P,������e��n��g�#@���J� lz��E��U�,�Ã�K��p$�F��~���1��:M� ����]�r`���|,��N�3����������tI/��bO��,�I���m�?�-x5vώ�jrt��Nm��lo����C�c��6�A���"? More languages soon. This dust is then transported inward past the orbit of Epsilon Eridani b. His catalogue assigned letters from the Greek alphabet to groups of stars belonging to the same visual magnitude class in each constellation, beginning with alpha (α) for a star in the brightest class. This stellar wind generates the astrosphere that spans about 8,000 au (0.039 pc) and contains a bow shock that lies 1,600 au (0.0078 pc) from Epsilon Eridani. Their model suggested that the clumping of the dust particles could be explained by the presence of a second planet in an eccentric orbit, which they announced in 2002. JJ�a-ٖl��.�E�I��Oo���X8��=�BX�/�6��x�=������� :�V*�٭3]��py���[� OF���}�C ��&2�k�Ɍ� W�$^:�O���F�����\�h\׸�ǍG^�ē啈륗5�*���ʹ��Y0�Ol��/��UB��}�L>e/~J���-ň��jei��%jm�w��#u��s��k�HCa���tr9��3��Ābu�����(�˺u^�ֽ��0�m��8��"�Q���V�1�lyG�1�������&V4�pV�˝�{���2��Esk5�̫_�,�S��NPw��B�ᮏ����.����t�lL��9�