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{{Starbox begin
| name = PSR J1719-1438
}}
{{Starbox image
| image = <!--image location (i.e. "Sunspots.png")-->
| caption = <!--caption (optional)-->
| credit = <!--credit for image if the image's use requires them (optional)-->
}}
{{Starbox observe
| epoch = [[Julian day#Alternatives|MJD]] 55411.0<ref name=bailes/><!--Epoch of observation-->
| equinox = [[J2000]]
| constell = [[Serpens]] 
| pronounce = <!--Pronunciation guide-->
| ra = 17:19:10.0730(1)<ref name=bailes/> <!--Right Ascension-->
| dec = −14:38:00.96(2)<ref name=bailes/> <!--Declination-->
| appmag_v =  <!--Apparent magnitude (Johnson-Cousins V  system)-->
}}
{{Starbox character
| class = [[millisecond pulsar]]<ref name=bailes/> <!--Stellar class-->
| appmag_1_passband = R<!-- Passband for first apparent magnitude (e.g., H, J, K, etc.) -->
| appmag_1 = >25.4<ref name=bailes/><!-- Value of first apparent magnitude  -->
| appmag_2_passband = g<!-- Passband for second apparent magnitude (e.g., H, J, K, etc.) -->
| appmag_2 = >24.1<ref name=bailes/><!-- Value of second apparent magnitude  -->
| appmag_3_passband = I<!-- Passband for third apparent magnitude (e.g., H, J, K, etc.) -->
| appmag_3 = >22.5<ref name=bailes/><!-- Value of third apparent magnitude  -->
| appmag_4_passband = <!-- Passband for fourth apparent magnitude (e.g., H, J, K, etc.) -->
| appmag_4 = <!-- Value of fourth apparent magnitude  -->
| appmag_5_passband = <!-- Passband for fifth apparent magnitude (e.g., H, J, K, etc.) -->
| appmag_5 = <!-- Value of fifth apparent magnitude  -->
| appmag_6_passband = <!-- Passband for sixth apparent magnitude (e.g., H, J, K, etc.) -->
| appmag_6 = <!-- Value of sixth apparent magnitude  -->
| appmag_7_passband = <!-- Passband for seventh apparent magnitude (e.g., H, J, K, etc.) -->
| appmag_7 = <!-- Value of seventh apparent magnitude  -->
| appmag_8_passband = <!-- Passband for eighth apparent magnitude (e.g., H, J, K, etc.) -->
| appmag_8 = <!-- Value of eighth apparent magnitude  -->
| r-i = <!--R-I color-->
| v-r = <!--V-R color-->
| b-v = <!--B-V color-->
| u-b = <!--U-B color-->
| j-h = <!--J-H color-->
| j-k = <!--J-K color-->
| variable = <!--Variability type-->
}}
{{Starbox astrometry
 | radial_v = <!--Radial velocity (in km/sec)-->
 | prop_mo_ra = <!--Proper motion (RA), μ<sub>α</sub> cos δ (in milliarcsec/yr)-->
 | prop_mo_dec = <!--Proper motion (dec), μ<sub>δ</sub> (in milliarcsec/yr)-->
 | parallax =  <!--Parallax (in milliarcsec)-->
 | p_error = <!--Parallax error (in milliarcsec)-->
 | parallax_footnote = <!--Parallax footnote-->
 | dist_ly = <!--Distance (in light years)-->
 | dist_pc = ~1,200<ref name=bailes/><!--Distance (in parsecs)-->
 | absmag_v = <!--Absolute magnitude ([[UBV photometric system|Johnson-Cousins V system]])-->
 }}
{{Starbox orbit
| reference = <ref name=bailes/><!--Reference-->
| primary = PSR J1719-1438<!--Primary name -->
| name = [[PSR J1719-1438b]]<!--Companion name-->
| period = <!--Period (in years)-->
| period_unitless = 0.090706293(2) days<!--Period (no units provided by template)-->
| axis = <!--Semimajor axis (in arcseconds)-->
| axis_unitless = <math>a_P\sin i=</math>0.001819(1) [[light second]]s<!--Semimajor axis (no units provided by template)-->
| eccentricity = <0.06 <!--Eccentricity-->
| inclination = <!--Inclination (in degrees)-->
| node = <!--Longitude of node (in degrees)-->
| periastron = [[Julian day#Alternatives|MJD]] 55411.0<!--Periastron epoch-->
| periarg = <!--Argument of periastron (in degrees), secondary -->
| periarg_primary = <!--Argument of periastron (in degrees), primary -->
| k1 = <!-- Velocity semi-amplitude (SB1, or primary in SB2), in km/s -->
| k2 = <!-- Velocity semi-amplitude (secondary in SB2), in km/s -->
}}
{{Starbox detail
| source              =   <!--[source url]-->
| mass                =   <!--Mass (in solar masses)-->
| radius              =   <!--Radius (in solar radii)-->
| gravity             =   <!--Surface gravity (given as the base 10 logarithm expressed in cgs units)-->
| luminosity          =   <!--Luminosity (in solar luminosities); prefer luminosity_bolometric or luminosity_visual-->
| luminosity_bolometric = <!--Luminosity (in solar luminosities), bolometric-->
| luminosity_visual   =   <!--Luminosity (in solar luminosities), visual (V)-->
| temperature         =   <!--Temperature (in kelvins)-->
| metal               =   <!--Metallicity (no units provided by template)-->
| rotation            =   <!--Rotation (no units provided by template)-->
| rotational_velocity =   <!--Rotational velocity (v sin i, in km/s)-->
| age                 =   <!--Age (in years)-->
| age_gyr             =   <!--Age (in billions of years)-->
}}
{{Starbox catalog
| names = <!--Other catalog designations-->
}}
{{Starbox reference
| Simbad = <!--Search String-->
}}
{{Starbox end}}

'''PSR J1719-1438''' is a [[millisecond pulsar]] with a spin period of 5.8 ms located about 4000 [[light year|ly]] from Earth in the direction of [[Serpens]] Cauda,<ref name=bailes/><ref name=UniverseToday /> one minute from the border with Ophiuchus. Millisecond pulsars are generally thought to begin as normal pulsars and then spin up by accreting matter from a [[Binary star|binary]] companion.

==Diamond planet==
{{main|PSR J1719-1438 b}}
PSR J1719-1438 was discovered in 2011 by the High Time Resolution Survey, a [[radio astronomy]] search for astronomical objects that rapidly vary in radio brightness, such as pulsars.<ref name=bailes/> Timing measurements using the [[Parkes Telescope]] and [[Lovell Telescope]] showed that it has a low-mass companion: [[PSR J1719-1438 b]].<ref name=bailes/> The companion has a mass similar to that of [[Jupiter]], but 40% of the diameter. It orbits the pulsar with a period of 2 hours 10 minutes and 37 seconds, at a distance of around 600,000&nbsp;km (0.89 [[Solar radius|solar radii]]).<ref name=bailes/> The companion is likely the remnant of a star whose outer layers were siphoned off by the more massive pulsar. Calculations show the companion has a minimum density of 23 grams per cubic centimeter and is probably an ultra-low-mass carbon–oxygen [[white dwarf]].<ref name=bailes/>

Because the companion to PSR J1719-1438 is planet-sized, made primarily of carbon (with an unknown amount of oxygen), and very dense, it may be similar to a large diamond. In the science press, the object has been called the [[Carbon planet|"Diamond Planet"]].<ref name=UniverseToday>{{cite web|title=Star Transforms Into A Diamond Planet|url=http://www.universetoday.com/88449/star-transforms-into-a-diamond-planet|work=Universe Today|accessdate=2011-08-26}}</ref><ref name=Space.com>{{cite web|title=Surprise! Alien Planet Made of Diamond Discovered|url=http://www.space.com/12731-diamond-alien-planet-discovered-neutron-star.html|work=Space.com|accessdate=2011-08-25}}</ref><ref name= MaxPlanck>{{cite web|title=A Planet made of Diamond|url=http://www.mpifr-bonn.mpg.de/public/pr/pr-pulsar-august2011-en.html|work=Max Planck Institut for Radio Astronomy|accessdate=2011-08-26}}</ref>

==See also==
* [[EF Eridani]], a star system with a compact star and a degraded planetary-mass former star

==References==
{{reflist|colwidth=25em|refs=

<ref name=bailes>
{{cite journal|doi=10.1126/science.1208890|title=Transformation of a Star into a Planet in a Millisecond Pulsar Binary|year=2011|last1=Bailes|first1=M.|last2=Bates|first2=S. D.|last3=Bhalerao|first3=V.|last4=Bhat|first4=N. D. R.|last5=Burgay|first5=M.|last6=Burke-Spolaor|first6=S.|last7=d'Amico|first7=N.|last8=Johnston|first8=S.|last9=Keith|first9=M. J.|journal=Science|bibcode = 2011Sci...333.1717B|pmid=21868629|volume=333|issue=6050|pages=1717–20|arxiv = 1108.5201 }}
</ref>

}}

{{Stars of Serpens}}

[[Category:Astronomical objects discovered in 2010]]
[[Category:Millisecond pulsars]]
[[Category:Planetary systems]]
[[Category:Serpens (constellation)]]