HD 147513 / HR 6094 AB

Star A was probably first observed and listed as CD-38 10983 during a visual survey of southern stars begun in 1892 at the Astronomical Observatory of Cordoba in Argentina under the direction of its second director John M. Thome (1843-1908). Thome died before the completion of this southern sky atlas in 1914, when 578,802 stars from declination -22° to -90° were published as the Cordoba Durchmusterung ("Survey"). The "CD" is an extension of an older catalogue by Friedrich Wilhelm August Argelander (1799-1875) in 1863 on the position and brightness of 324,198 stars between +90° and -2° declination that were measured over 11 years from Bonn, Germany, made with his assistants Eduard Schönfeld (1828-1891) and Aldalbert Krüger (1832-1896), which became famous as the Bonner Durchmusterung ("Bonn Survey") abbreviated as BD. The BD and CD were greatly expanded and extended into the modern age of photographic surveys with the subsequent creation of the Cape Photographic Durchmusterung from South Africa. (More discussion on star names and catalogue numbers is available from Alan MacRobert at Sky and Telescope and from Professor James B. Kaler's Star Names.)

HD 147513 A

HD 147513 A is a yellow-range dwarf star of spectral and luminosity type G3-5 V. It has about 92 percent of Sol's mass (press release), 105 percent of its diameter (Johnson and Wright, 1983, page 685), and about 96 percent of its luminosity. The star is only around 300 million years old and about 93 percent as enriched as Sol with iron.

HD 147513 A is a so-called young "Barium dwarf" (s-process element rich but comparatively carbon deficient) star that was probably enriched by an asymptotic branch giant (AGB) star (see Gacrux) but is now a very dim, white dwarf companion, which has an observed separation of around 4,400 AUs -- 5.7' at a HIPPARCOS distance estimate of 42.0 ly (Porto de Mello and da Silva, 1997; and Poveda et al, 1993, pp. 74-75). There is another Barium-dwarf candidate star, Chi1 Orionis or HR 2047 (G0 V), in the same Ursa Major stellar moving group, which suggests that all three stars may have formed a multiple system until their orbital stability was disrupted when the once, brighter and bigger AGB star shed most of an estimated original mass of 2.6 Solar to reveal its white dwarf core about 30 million years ago (Porto de Mello and da Silva, 1997). HD 147513 A is a New Suspected Variable star designated NSV 7680. Useful catalogue numbers and designations for this star include: HR 6094*, Gl 620.1, Hip 80337, HD 147513, CD-38 10983, CP(D)-38 6407, SAO 207622, FK5 3295, and Wo 9559.

Planet "b" (or "A1")

NASA

Cassini-Huygens Mission
to Saturn and Titan


Larger image.


Planet b or A1 is probably a gas giant
with a minimum mass around that
of Jupiter (shown here with Europa).

On June 18, 2002, a team of astronomers (including Dominique Naef, Francisco Pepe, Michel Mayor, Nuno C. Santos, Didier Queloz, and Stephane Udry) announced the discovery of a giant planet around this Sun-like star (Observatoire de Genève). Radial velocity measurements suggest that HD 147513 has a companion "b" (or "A1") with at least 1.0 times Jupiter's mass. It moves around HD 147513 at an average distance of 1.26 AUs (a semi-major axis just inside the orbital distance of Mars) in a highly eccentric orbit (e=0.52) that takes about 540 days (or 1.48 years) to complete. (See an animation of the planetary and potentially habitable zone orbits of the HD 147513 A system, with a table of basic orbital and physical characteristics.)

The orbit of an Earth-like planet (with liquid water) around HD 147513 A may be centered around 0.98 AUs -- almost the same orbital distance as Earth in the Solar System -- with an orbital period around 370 days (or 1.01 years). However, the orbit of planet b or A1 with an average distance of 1.26 AUs would disrupt the orbital stability of an Earth-type planet in HD 147513 A's water zone. Astronomers are hoping to use NASA's Terrestrial Planet Finder (TPF) and the ESA's Darwin planned groups of observatories to search for a rocky inner planet in the so-called "habitable zone" (HZ) around HD 147513 A. As currently planned, the TPF will include two complementary observatory groups: a visible-light coronagraph to launch around 2014; and a "formation-flying" infrared interferometer to launch before 2020, while Darwin will launch a flotilla of three mid-infrared telescopes and a fourth communications hub beginning in 2015.

H. Bond (STSci), R. Ciardullo (PSU), WFPC2, HST, NASA

HD 147513 B is a young white dwarf (a remnant stellar core which enriched its binary companion, Star A)
with elements heavier than hydrogen when it cast off its outer gas layers) like planetary nebula NGC 2440.

HD 147513 B

Star A is a white dwarf stellar remnant of spectral and luminosity type DA2 /VII. It probably 65 percent of Sol's mass (Gustavo Porto de Mello, 2002; and Porto de Mello and da Silva, 1997), a planet-sized diameter, and less than 0.6 percent of Sol's luminosity. Originally, it may have been a 2.6 Solar-mass star that shed the remainder of its gaseous envelope about 30 million years ago (Porto de Mello and da Silva, 1997; and Holberg et al, 1995). It shares the same common proper motion as Star A and appears to be intermediate in mass and size between Sirius B and 40 Eridani B (Gary Wegner, 1978). Useful catalogue numbers and designations for this star include: Gl620.1 B, Hip 80300, CD-38 10980, CP(D)-38 6406, and EG 274.