en>Circlesareround: /* Metric formulas */ another area formula

2012-11-01T07:34:43Z

Metric formulas: another area formula

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{{Starbox begin
| name = HD 154088
}}
{{Starbox observe
| epoch = J2000.0
| constell = [[Ophiuchus]]
| ra = {{RA|17|04|27.84}} ± 5.62<ref name="van Leeuwen2007"/>
| dec = {{DEC|-28|34|57.64}} ± 3.16<ref name="van Leeuwen2007"/>
| appmag_v = 6.7258 ± 0.005<ref name="van Leeuwen2007"/>
}}
{{Starbox character
| class = K0V
| b-v = 0.814 ± 0.034<ref name="van Leeuwen2007"/>
}}
{{Starbox astrometry
| radial_v = 14.2972 ± 0.0003<ref name="Mayor2011"/>
| prop_mo_ra = 83.76 ± 0.64<ref name="van Leeuwen2007"/>
| prop_mo_dec = -268.69 ± 0.36<ref name="van Leeuwen2007"/>
| parallax = 56.06
| p_error = 0.50
| parallax_footnote = <ref name="van Leeuwen2007"/>
| absmag_v = 4.978 ± 0.018<ref name="AbsMag"/>
}}
{{Starbox detail
| mass = 0.97 ± 0.05<ref name="Fossati2013"/>
| metal_fe = 0.31 ± 0.03<ref name="Fossati2013"/>
| radius = 0.95 ± 0.03<ref name="Takeda2007"/>
| luminosity = 0.68 {{±|0.06|0.05}} (log -0.169 ± 0.033)<ref name="Valenti2005"/>
| temperature = 5423 ± 51<ref name="Fossati2013"/>
| gravity = 4.40 ± 0.11<ref name="Fossati2013"/>
| rotational_velocity = 1.9 ± 0.5<ref name="Valenti2005"/>
| rotation = 42.6 ± 4.4<ref name="Lovis2011"/>
| age_gyr = 3 - 8<ref name="Fossati2013"/>
}}
{{Starbox catalog
| names = HIP 83541, Gliese 652
}}
{{Starbox reference
| Simbad = HD+154088
| EPE = HD+154088
}}
{{Starbox end}}

'''HD 154088''' is a seventh magnitude metal-rich [[K-type main sequence star]] that lies approximately 58 [[light-year]]s away in the constellation of [[Ophiuchus]]. The star is orbited by a hot [[Super-Earth]].

==Properties==
<div style="position: relative">[[File:HRDiagram.png|thumb|left|The position of HD 154088 on the [[Hertzsprung-Russell diagram]].]]
<div style="position: absolute; left: 96px; top: 127px">[[File:Chess tile xg.svg|20px]]</div>
</div>
HD 154088 is a modestly bright star that lies at the bottom of Ophiuchus, near to the border with Scorpius and near to the plane of the Milky Way. The star was recognised as a high proper motion star during the last century, and early Earth-based parallax measurements such as that of the [[Gliese Catalogue of Nearby Stars]] indicated a distance of about 50 light-years.

The star has a spectral type of K0V, indicating that it is a main sequence star that is about 350 degrees cooler than the Sun. On the [[Hertzsprung-Russell diagram]] (left), the star lies slightly above the main sequence. This is because the star is very [[metallicity|metal-rich]]; with an Fe/H of 0.3 dex the star has about twice the solar abundance of iron, which makes HD 154088 fall into the somewhat vague group of super metal-rich (SMR) stars. The giant planet occurrence rate of Fe/H = 0.3 stars is on the order of 30%, but HD 154088 is not currently known to host any giant planets.

HD 154088 has a pronounced magnetic field.<ref name="Fossati2013"/> It also has a magnetic cycle similar to the Sun,<ref name="Lovis2011"/> though its length is not well constrained.

==Planetary system==
A planet orbiting HD 154088 discovered with the [[High Accuracy Radial Velocity Planet Searcher|HARPS]] spectrograph was announced in September 2011. With a minimum mass of 6 Earth masses, the companion falls into the regime of Super-Earths.

{{OrbitboxPlanet begin
| table_ref=<ref name=Mayor2011/>
}}
{{OrbitboxPlanet
| exoplanet = b
| mass_earth = ≥6.15 ± 0.86
| period = 18.596 ± 0.021
| semimajor = 0.1316 ± 0.0021
| eccentricity = 0.38 ± 0.15
}}
{{Orbitbox end}}

HD 154088 is also being observed under the [[W. M. Keck Observatory|Keck]] Eta-Earth radial velocity survey.<ref name="Howard2010"/> HD 154088 b is a close match for planet candidate 1 (orbital period = 18.1 days, minimum mass = 6.5 M<sub>⊕</sub>), so they may be the same detection.

==References==
{{reflist|refs

<ref name="van Leeuwen2007">{{cite journal | url=http://www.aanda.org/index.php?option=com_article&access=bibcode&Itemid=129&bibcode=2007A%2526A...474..653VFUL | title=Validation of the new Hipparcos reduction | last1=van Leeuwen | first1=F. | journal=Astronomy and Astrophysics | volume=474 | issue=2 | pages=653–664 | year=2007 | arxiv=0708.1752 | bibcode=2007A&A...474..653V | doi=10.1051/0004-6361:20078357 }}</ref>

<ref name="Mayor2011">{{cite journal | title=The HARPS search for southern extra-solar planets XXXIV. Occurrence, mass distribution and orbital properties of super-Earths and Neptune-mass planets | last1=Mayor | first1=M. | coauthors = ''et al.'' | year=2011 | arxiv=1109.2497 |bibcode = 2011arXiv1109.2497M }}</ref>

<ref name="AbsMag">The relevant calculation for absolute magnitude is <math> M = m - 5 ((\log_{10}{D_L}) - 1)\!\,</math>, where <math>m\!\,</math> is the apparent magnitude and <math>D_L\!\,</math> is the distance in light-years.</ref>

<ref name="Fossati2013">{{cite journal | title=Detection of a magnetic field in three old and inactive solar-like planet-hosting stars | last1=Fossati | first1=L. | coauthors = ''et al.'' | year=2013 | arxiv=1302.0879 | bibcode=2013A&A...551A..85F | doi=10.1051/0004-6361/201220997 }}</ref>

<ref name="Takeda2007">{{cite journal | title=Structure and Evolution of Nearby Stars with Planets. II. Physical Properties of ~1000 Cool Stars from the SPOCS Catalog | last1=Takeda | first1=Genya | coauthors = ''et al.'' | year=2007 | arxiv=astro-ph/0607235 | bibcode=2007ApJS..168..297T | doi=10.1086/509763 }}</ref>

<ref name="Valenti2005">{{cite journal | title=Spectroscopic Properties of Cool Stars (SPOCS). I. 1040 F, G, and K Dwarfs from Keck, Lick, and AAT Planet Search Programs | last1=Valenti | first1=J. A. | last2=Fischer | first2=D. A. | year=2005 | bibcode=2005ApJS..159..141V | doi=10.1086/430500 }}</ref>

<ref name="Lovis2011">{{cite journal | title=The HARPS search for southern extra-solar planets. XXXI. Magnetic activity cycles in solar-type stars: statistics and impact on precise radial velocities | last1=Lovis | first1=C. | coauthors = ''et al.'' | year=2011 | arxiv=1107.5325 |bibcode = 2011arXiv1107.5325L }}</ref>

<ref name="Howard2010">{{cite journal | title=The Occurrence and Mass Distribution of Close-in Super-Earths, Neptunes, and Jupiters | last1=Howard | first1=Andrew A. | coauthors = ''et al.'' | year=2010 | arxiv=1011.0143 | bibcode=2010Sci...330..653H | doi=10.1126/science.1194854 }}</ref>

}}

{{Sky|17|04|27.84|-|28|34|57.64|58}}

{{Nearest star systems|12}}

{{Stars of Ophiuchus}}

[[Category:Ophiuchus (constellation)]]
[[Category:Henry Draper Catalogue objects|154088]]
[[Category:Hipparcos objects|83541]]
[[Category:Gliese and GJ objects|0652]]
[[Category:K-type main-sequence stars]]

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en>Circlesareround: /* Metric formulas */ another area formula