BD+14 4559 b
{{Short description|Gas giant exoplanet in the habitable zone}}
{{Use dmy dates|date=August 2023}}
{{Infobox planet
| name = BD+14 4559b / Pirx
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| image = BD +14 4559 b exoplanet view from it's moon (artist's impression).jpg
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| caption = Artist's impression of the exoplanet BD+14 4599 b. View from the surface of its hypothetical moon.
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| discoverer = Andrzej Niedzielski
| discovery_site = La Silla Observatory
| discovered = June 10, 2009
| discovery_method = radial velocity
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| minorplanet = no
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| apsis = astron
| aphelion = {{convert|1.002|AU|km|abbr=on}}
| perihelion = {{convert|0.552|AU|km|abbr=on}}
| semimajor = {{convert|0.777|AU|km|abbr=on}}
| mean_orbit_radius =
| eccentricity = 0.29 ± 0.03
| period = 268.94 ± 0.99 d
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| long_periastron =
| time_periastron = 53293.71 ± 6.35
| arg_peri = 87.64 ± 7.87
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| mean_radius = ~1.05 {{Jupiter radius|link=y}}
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| single_temperature = {{convert|205|K|C F}}
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BD+14 4559 b, named Pirx, is an exoplanet orbiting the K-type main sequence star BD+14 4559 about 161 light-years (49 parsecs, or nearly {{val|1.5|e=15}} km) from Earth in the constellation Pegasus. It orbits its star within the habitable zone at a distance of 0.777 AU, close to that of Venus, but its star is less energetic, thus its habitable zone is closer to it than Earth. The exoplanet was found by using the radial velocity method, from radial-velocity measurements via observation of Doppler shifts in the spectrum of the planet's parent star.
The planet was named during the NameExoWorlds campaign by Poland. Pilot Pirx is a fictional character from stories by Polish science-fiction writer Stanisław Lem.{{Cite web|url=http://www.nameexoworlds.iau.org/final-results|title=Approved names|website=NameExoworlds|language=en|access-date=2020-01-02}}
Characteristics
=Mass, radius and temperature=
BD+14 4559 b is a gas giant, an exoplanet that has a radius and mass around that of the gas giants Jupiter and Saturn. It has a temperature of {{convert|205|K|C F}}.[http://www.hpcf.upr.edu/~abel/phl/hec_plots/hec_orbit/hec_orbit_BD14_4559_b.png BD14 4559] hpcf.upr.edu It has an estimated mass of around 1.2 {{Jupiter mass}} and a potential radius of around 1.05 {{Jupiter radius}} based on its mass.{{citation needed|date=September 2020}}
=Host star=
{{main|BD+14 4559}}
The planet orbits a (K-type) star named BD+14 4559. The star has a mass of 0.86 {{Solar mass}} and a radius of around 0.95 {{Solar radius}}. It has a surface temperature of 5008 K and is likely about 3 billion years old based on its evolution and mass. In comparison, the Sun is about 4.6 billion years old{{cite web |url=http://www.universetoday.com/18237/how-old-is-the-sun/ |title=How Old is the Sun? |author=Fraser Cain |date=16 September 2008 |website= |publisher=Universe Today |accessdate=19 February 2011}} and has a surface temperature of 5778 K.{{cite web |url=http://www.universetoday.com/18092/temperature-of-the-sun/ |title=Temperature of the Sun |author=Fraser Cain |date=September 15, 2008 |website= |publisher=Universe Today |accessdate=19 February 2011}}
The star's apparent magnitude, or how bright it appears from Earth's perspective, is 9.63. Therefore, BD+14 4559 is too dim to be seen with the naked eye, but can be viewed using good binoculars.{{citation needed|date=September 2020}}
=Orbit=
Discovery
The search for BD+14 4559 b started when its host star was chosen an ideal target for a planet search using the radial velocity method (in which the gravitational pull of a planet on its star is measured by observing the resulting Doppler shift), as stellar activity would not overly mask or mimic Doppler spectroscopy measurements. It was also confirmed that BD+14 4559 is neither a binary star nor a quickly rotating star, common false positives when searching for transiting planets. Analysis of the resulting data found that the radial velocity variations most likely indicated the existence of a planet. The net result was an estimate of a 1.47 {{Jupiter mass}} planetary companion orbiting the star at a distance of 0.77 AU with an eccentricity of 0.29.
Radial velocity measurements of BD+14 4559 were measured at 43 epochs over the period of roughly 1,265 days (around 4 years) using the Hobby–Eberly Telescope. Measurements determined that a signal-to-noise ratio per resolution element was around 150–260 at 594 nm in 10 to 25 minutes of integration. The estimated mean RV uncertainty for the parent star was estimated at 8 m s−1.
The discovery of BD+14 4559 b was reported in the journal The Astrophysical Journal on June 10, 2009.
See also
References
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{{Sky|21|13|35.99|+|14|41|21.8}}
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Category:Exoplanets discovered in 2009
Category:Pegasus (constellation)
Category:Exoplanets detected by radial velocity
Category:Giant planets in the habitable zone