View source for Astronomy:WD 0145+234

{{Short description|White dwarf in the constellation Aries}}
{{sky|01|47|54.81|+|23|39|43.6|98.08}}
{{Starbox begin
| name = WD 0145+234
}}
{{Starbox observe
| constell = [[Astronomy:Aries (constellation)|Aries]]<ref name="DJM-2008">{{cite web |author=Staff |title=Finding the constellation which contains given sky coordinates |url=http://djm.cc/constellation.html |date=2 August 2008 |work=DJM.cc |access-date=29 August 2019 }}</ref>
| epoch = [[Astronomy:J2000.0|J2000.0]]
| ra = {{RA|01|47|54.81}}<ref name="SIMBAD-2019">{{cite web |author=Staff |title=WD 0145+234 |url=http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=WD+0145%2B234 |date=2019 |work=[[Astronomy:SIMBAD|SIMBAD]] |access-date=17 October 2019 }}</ref><ref name="ARX-20191010" />
| dec = {{DEC|+23|39|43.6}}<ref name="SIMBAD-2019" /><ref name="ARX-20191010" />
| appmag_v = 11.64<ref name="VE-2019">{{cite web |author=Staff |title=WD0145+234 |url=http://www.astronomy.villanova.edu/WDCatalog/WDhtm/WD0145+234.htm |date=2019 |work=Villanova University |access-date=17 October 2019 }}</ref>
}}
{{Starbox character
| class = [[Astronomy:Stellar classification#White dwarf classification|DA]]<ref name="SIMBAD-2019" />
}}
{{Starbox astrometry
| dist_pc = 29.458<ref name="ARX-20191010" />
| dist_ly = 98.08
}}
{{Starbox detail
| mass =
| radius = 
| temperature = 12910<ref name="SIMBAD-2019" />
| metal_fe = 
| age_gyr = 
}}
{{Starbox catalog
| names = WD 0145+234; 2MASS J01475481+2339437; 1SWASP J014754.80+233943.8; Gaia DR2 291057843317534464; CHSS 3403; Mrk 362; WD 0145+23}}
{{Starbox reference
| Simbad = WD+0145%2B234
}}
{{Starbox end}}

'''WD 0145+234''' is a [[Astronomy:White dwarf|white dwarf star]] approximately {{convert|29|pc|ly|abbr=on|order=flip}}<ref name="ARX-20191010" /> from Earth in the constellation of [[Astronomy:Aries (constellation)|Aries]] that has been associated with studies suggesting that a very large [[Astronomy:Exoasteroid|exoasteroid]] near the star was substantially disrupted, resulting in a considerable amount of dust and debris around the star.<ref name="ARX-20191010">{{cite arXiv |author=Wang, Ting-gui |display-authors=et al. |title=An On-going Mid-infrared Outburst in the White Dwarf 0145+234: Catching in Action of Tidal Disruption of an Exoasteroid? |date=10 October 2019 |eprint=1910.04314v1 |class=astro-ph.SR }}</ref><ref name="LS-20191017">{{cite news |last=Letzer |first=Rafi |title=An Asteroid-Smashing Star Ground a Giant Rock to Bits and Covered Itself in the Remains |url=https://www.livescience.com/white-dwarf-asteroid-smasher.html |date=17 October 2019 |work=LiveScience |access-date=17 October 2019 }}</ref> Alternatively, the outburst around WD 0145+234 is explained with ongoing collisions between [[Astronomy:Planetesimal|planetesimals]] inside the dusty debris disk around the white dwarf.<ref name=":0">{{Cite journal |last1=Swan |first1=Andrew |last2=Kenyon |first2=Scott J. |last3=Farihi |first3=Jay |last4=Dennihy |first4=Erik |last5=Gänsicke |first5=Boris T. |last6=Hermes |first6=J. J. |last7=Melis |first7=Carl |last8=von Hippel |first8=Ted |date=2021-09-01 |title=Collisions in a gas-rich white dwarf planetary debris disc |journal=Monthly Notices of the Royal Astronomical Society |volume=506 |issue=1 |pages=432–440 |doi=10.1093/mnras/stab1738 |pmid=34248393 |pmc=8263348 |arxiv=2106.09025 |bibcode=2021MNRAS.506..432S |issn=0035-8711}}</ref>

The outburst around WD 0145+234 appeared in 2018 in data by the [[Astronomy:Wide-field Infrared Survey Explorer|Wide-Field Infrared Survey Explorer]]. Outburst around white dwarfs in the infrared are not unusual. [[Astronomy:Nova|Novae]] and [[Astronomy:Dwarf nova|dwarf novae]] also show outbursts, but they are accompanied by an outburst in the optical and appear around [[Astronomy:Binary star|binaries]]. WD 0145+234 is however a single white dwarf and did not show any brightening in the optical images taken by [[Astronomy:Catalina Real-time Transient Survey|CRTS]] and [[Astronomy:All Sky Automated Survey for SuperNovae|ASASSN]]. This suggested that the outburst was caused by recent replenishing or redistribution of dust.<ref name="ARX-20191010" /> A follow-up study using the [[Astronomy:Spitzer Space Telescope|Spitzer Space Telescope]] found a decrease of the infrared brightness, beginning in late 2019. The decrease is accompanied by small bumps superimposed on the decrease of infrared brightness. The team studying WD 0145+234 with Spitzer concluded that the increase of brightness was not caused by the a tidal disruption of an exoasteroids, but by ongoing collisions in the disk around the white dwarf. A similar decrease in infrared brightness was found around the white dwarf GD 56.<ref name=":0" /> WD 0145+234 is also unusual because not only does it show metal pollution in the form of absorption lines, which are found around 25-50% of white dwarfs, but also emission lines caused by [[Chemistry:Calcium|calcium]] gas, which are less common.<ref>{{Cite journal |last1=Melis |first1=Carl |last2=Klein |first2=Beth |last3=Doyle |first3=Alexandra E. |last4=Weinberger |first4=Alycia |last5=Zuckerman |first5=B. |last6=Dufour |first6=Patrick |date=2020-12-01 |title=Serendipitous Discovery of Nine White Dwarfs with Gaseous Debris Disks |journal=The Astrophysical Journal |volume=905 |issue=1 |pages=56 |doi=10.3847/1538-4357/abbdfa |arxiv=2010.03695 |bibcode=2020ApJ...905...56M |s2cid=222208858 |issn=0004-637X |doi-access=free }}</ref> It is still not clear what causes the metal emission lines around some white dwarfs, but the existence of such lines around WD 0145+234 suggests that metal gas is formed in collisions. There are still some unanswered questions for this hypothesis: Some white dwarfs with metal gas show variable emission lines, while WD 0145+234 does not show any variability in the calcium emission line. It is unclear why some white dwarfs show variable metal emission lines.<ref name=":0" />

Other white dwarfs with planetary pollution also show infrared variability, with the prototype being [[Astronomy:G 29-38|G29-38]], which showed a decrease of infrared flux by about 35% over a period of 300 days.<ref>{{Cite journal |last1=Xu |first1=S. |last2=Jura |first2=M. |date=2014-09-01 |title=The Drop during Less than 300 Days of a Dusty White Dwarf's Infrared Luminosity |url=https://ui.adsabs.harvard.edu/abs/2014ApJ...792L..39X |journal=The Astrophysical Journal |volume=792 |issue=2 |pages=L39 |doi=10.1088/2041-8205/792/2/L39 |arxiv=1408.1618 |bibcode=2014ApJ...792L..39X |s2cid=118342404 |issn=0004-637X}}</ref> White dwarfs with the highest infrared variations show calcium emission lines, just like WD 0145+234.<ref>{{Cite journal |last1=Swan |first1=Andrew |last2=Farihi |first2=Jay |last3=Wilson |first3=Thomas G. |last4=Parsons |first4=Steven G. |date=2020-08-01 |title=The dust never settles: collisional production of gas and dust in evolved planetary systems |url=https://ui.adsabs.harvard.edu/abs/2020MNRAS.496.5233S |journal=Monthly Notices of the Royal Astronomical Society |volume=496 |issue=4 |pages=5233–5242 |doi=10.1093/mnras/staa1688 |arxiv=2006.05999 |bibcode=2020MNRAS.496.5233S |issn=0035-8711}}</ref> WD 0145+234 might be the system with one of the highest activity of this class of objects.<ref name=":0" />

Observations with [[Astronomy:NIRSpec|NIRSpec]] released in a [[Preprint|preprint]] in October 2023 showed that the debris disk is returning to its quiescent state. [[Engineering:Mid-Infrared Instrument|MIRI]] spectroscopy showed emission at 9-12 [[Micrometre|micron]], consistent with [[Chemistry:Silicate mineral|silicate minerals]] and a tentative emission feature around 7 microns was interpreted as [[Chemistry:Carbonate|carbonates]]. The authors noted that emission of silicate minerals begins at 9 microns and therefore resembles more the emission feature of [[Chemistry:Enstatite|enstatite]] than that of [[Chemistry:Forsterite|fosterite]].<ref>{{Cite journal |last1=Swan |first1=Andrew |last2=Farihi |first2=Jay |last3=Su |first3=Kate Y. L. |last4=Desch |first4=Steven J. |date=17 October 2023 |title=The first white dwarf debris disk observed by JWST |url=https://ui.adsabs.harvard.edu/abs/2023arXiv231009355S/abstract |journal=MNRAS Letters |arxiv=2310.09355 |bibcode=2023arXiv231009355S}}</ref>
[[File:JPL-AsteroidDisruptedByStar-ArtistConcept.jpg|thumb|center|300px|<div align="center">Exoasteroid disrupted by star (artist concept)</div>]]

== See also ==
* [[Astronomy:Disrupted planet|Disrupted planet]]
* List of stars that have unusual dimming periods
* [[Astronomy:Tabby's Star|Tabby's Star]]
* [[Astronomy:WD 1145+017|WD 1145+017]]

== References ==
{{reflist}}

{{Stars of Aries}}
{{2019 in space}}
{{DEFAULTSORT:WD 0145+234}}
[[Category:Aries (constellation)]]
[[Category:White dwarfs]]

{{Sourceattribution|WD 0145+234}}