{{Short description|Star in the constellation Centaurus}} {{Starbox begin |name=HD 101584 }} {{Starbox image |image=[[File:HD 101584.jpg|250px]] |caption=HD 101584 seen by [[Atacama Large Millimeter Array|ALMA]]. The blue component moves towards the observer and the red component moves away from the observer. The green component has the same speed as the binary system, seen as a green point source in the middle. |credit=ALMA (ESO/NAOJ/NRAO), Olofsson et al.<br />Acknowledgement: Robert Cumming }} {{Starbox observe |epoch=[[J2000.0]] |constell=[[Centaurus]] |ra={{RA|11|40|58.80515}}<ref name=dr3/> |dec={{DEC|-55|34|25.8147}}<ref name=dr3/> |appmag_v=7.01 }} {{Starbox character |class=A6Ia<ref>{{Cite journal|last1=Sivarani|first1=T.|last2=Parthasarathy|first2=M.|last3=García-Lario|first3=P.|last4=Manchado|first4=A.|last5=Pottasch|first5=S. R.|date=June 1999|title=Spectroscopy of the post-AGB star HD 101584 (IRAS 11385-5517)|journal= Astronomy and Astrophysics Supplement Series|language=en|volume=137|issue=3|pages=505–519|doi=10.1051/aas:1999259|issn=0365-0138|bibcode=1999A&AS..137..505S|arxiv=astro-ph/9907310|s2cid=16274320}}</ref> }} {{Starbox astrometry | radial_v = | prop_mo_ra = −7.935<ref name=dr3/> | prop_mo_dec = −0.243<ref name=dr3/> | parallax = 0.5452 | p_error = 0.0199 | parallax_footnote = <ref name=dr3>{{cite Gaia DR3|5343168568718268800}}</ref> | absmag_v }} {{Starbox detail | component1 = supergiant | mass = 0.5 - 1<ref name="Olofsson et al"/> | temperature = 8,500<ref>{{cite journal |bibcode=2021A&A...651A..35O |title=Heavy-element Rydberg transition line emission from the post-giant-evolution star HD 101584 |last1=Olofsson |first1=H. |last2=Black |first2=J. H. |last3=Khouri |first3=T. |last4=Vlemmings |first4=W. H. T. |last5=Humphreys |first5=E. M. L. |last6=Lindqvist |first6=M. |last7=Maercker |first7=M. |last8=Nyman |first8=L. |last9=Ramstedt |first9=S. |last10=Tafoya |first10=D. |journal=Astronomy and Astrophysics |year=2021 |volume=651 |pages=A35 |doi=10.1051/0004-6361/202140537 |arxiv=2105.00699 |s2cid=233481052 }}</ref> | luminosity = {{solar luminosity|1,600}} (@1kpc) {{nowrap|(400 - 5,000)<ref name="Olofsson et al"/>}} | radius = 18.6<ref name="Olofsson et al"/> | component2 = companion | mass2 = 0.27 - 0.41<ref name="Olofsson et al"/> }} {{Starbox catalog |names=[[IRAS]] 11385−5517, V885 Centauri, [[Hipparcos#Published catalogues|HIP]] 56992, [[2MASS]] J11405880−5534258 }} {{Starbox reference |Simbad=HD+101584 }} {{Starbox end}}
'''HD 101584''' is a suspected [[Post common envelope binary|post-common envelope binary]] about 1,800 to 5,900 [[light-year]]s distant in the constellation of [[Centaurus]].<ref name="Olofsson et al">{{Cite journal|last1=Olofsson|first1=H.|last2=Khouri|first2=T.|last3=Maercker|first3=M.|last4=Bergman|first4=P.|last5=Doan|first5=L.|last6=Tafoya|first6=D.|last7=Vlemmings|first7=W. H. T.|last8=Humphreys|first8=E. M. L.|last9=Lindqvist|first9=M.|last10=Nyman|first10=L.|last11=Ramstedt|first11=S.|date=March 2019|title=HD 101584: circumstellar characteristics and evolutionary status|journal= Astronomy & Astrophysics|language=en|volume=623|pages=A153|doi=10.1051/0004-6361/201834897|issn=0004-6361|bibcode=2019A&A...623A.153O|arxiv=1902.02153|s2cid=102480818}}</ref><ref name="ALMA press">{{Cite web|url=https://www.almaobservatory.org/en/audiences/alma-catches-beautiful-outcome-of-stellar-fight/|title=ALMA catches beautiful outcome of stellar fight|website=Atacama Large Millimeter/submillimeter Array}}</ref> The system is bright at optical wavelengths with an [[apparent visual magnitude]] of about 7. The primary is either a [[Post-AGB Star|post-AGB]] star, but more likely a post-[[Red-giant branch|RGB]] star. The secondary is a [[red dwarf]] or possibly a low-luminosity [[white dwarf]], which orbits the primary every 150-200 days. The system is surrounded by a slowly rotating [[Circumstellar disc#Binary system|circumbinary disk]], probably with a face-on orientation towards the [[Solar System]] and a size of about 150 [[astronomical unit]]s.<ref name="Olofsson et al"/>
== Variability == [[File:V885CenLightCurve.png|thumb|left|A [[light curve]] for V885 Centauri, plotted from ''Hipparcos'' data<ref name="CDS">{{cite web | url=https://cdsarc.cds.unistra.fr/viz-bin/ftp-index?/ftp/cats/more/HIP/cdroms/cats | website=Centre de Données astronomiques de Strasbourg | title=/ftp/cats/more/HIP/cdroms/cats | publisher=Strasbourg astronomical Data Center |access-date=15 October 2022}}</ref>]] In 1991, Jean Manfroid ''et al.'' published [[photometry (astronomy)|photometry]] that showed that HD 101584 is a [[variable star]].<ref name="Manfroid1991">{{cite journal |last1=Manfroid |first1=J. |last2=Sterken |first2=C. |last3=Bruch |first3=A. |last4=Burger |first4=M. |last5=de Groot |first5=M. |last6=Duerbeck |first6=H. W. |last7=Duemmler |first7=R. |last8=Figer |first8=A. |last9=Hageman |first9=T. |last10=Hensberge |first10=H. |last11=Jorissen |first11=A. |last12=Madejsky |first12=R. |last13=Mandel |first13=H. |last14=Ott |first14=H. A. |last15=Reitermann |first15=A. |last16=Schulte-Ladbeck |first16=R. E. |last17=Stahl |first17=O. |last18=Steenman |first18=H. |last19=Vander Linden |first19=D. |last20=Zickgraf |first20=F. J. |title=Long-term photometry of variables at ESO. I. The first data catalogue (1982-1986) |journal=Astronomy and Astrophysics, Suppl. Ser. |date=March 1991 |volume=87 |pages=481–498 | bibcode=1991A&AS...87..481M |url=https://articles.adsabs.harvard.edu/pdf/1991A%26AS...87..481M |access-date=20 January 2025}}</ref> HD 101584 has been given the [[variable star designation]] V885 Centauri. The International Variable Star Index states that the star varies between visual magnitude 6.90 and 7.02, over a period of 87.9 days.<ref name="IVSI">{{cite web |title=V0885 Cen |url=https://www.aavso.org/vsx/index.php?view=detail.top&oid=8182 |website=The International Variable Star Index |publisher=AAVSO |access-date=21 October 2022}}</ref> However Koen and Eyer detected, in the star's ''[[Hipparcos]]'' data, an oscillation of the star's brightness with a period of 6.744 days and an amplitude of only 0.02 magnitudes.<ref name="Koen">{{cite journal |last1=Koen |first1=Chris |last2=Eyer |first2=Laurent |title=New periodic variables from the Hipparcos epoch photometry |journal=Monthly Notices of the Royal Astronomical Society |date=March 2002 |volume=331 |issue=1 |pages=45–59 |doi=10.1046/j.1365-8711.2002.05150.x |arxiv=astro-ph/0112194 |bibcode=2002MNRAS.331...45K |doi-access=free }}</ref> {{clear left}}
== Nebula == [[File:HD 101584 Hubble.jpg|thumb|left|HD 101584 and the surrounding nebula, seen by [[Hubble Space Telescope|Hubble]]]] The [[Hubble Space Telescope]] image shows a diffuse [[Circumstellar disc|circumstellar]] environment with a circular ring around HD 101584. [[Atacama Large Millimeter Array|ALMA]] mapped the nebula around HD 101584 and was able to map the region close to the central binary. The nebula consists of a central compact source, an equatorial density enhancement (disk), a high-velocity bipolar outflow and an hourglass structure surrounding the outflow. The outflow reaches a maximum velocity of about 150 [[km/s]] and is inclined to the line of sight by {{val|10|10|5}}[[Degree (angle)|°]]. There is evidence for a second bipolar outflow with a different orientation from the major outflow.<ref name="Olofsson et al"/> The inner disk, heated to 1540 [[Kelvin|K]], currently has been sublimated by the increasing luminosity of the star.<ref>{{citation|arxiv=2008.11555|year=2020|title=VLTI/PIONIER reveals the close environment of the evolved system HD 101584|doi=10.1051/0004-6361/202037946 |last1=Kluska |first1=J. |last2=Olofsson |first2=H. |last3=Van Winckel |first3=H. |last4=Khouri |first4=T. |last5=Wittkowski |first5=M. |last6=De Wit |first6=W. J. |last7=Humphreys |first7=E. M. L. |last8=Lindqvist |first8=M. |last9=Maercker |first9=M. |last10=Ramstedt |first10=S. |last11=Tafoya |first11=D. |last12=Vlemmings |first12=W. H. T. |journal=Astronomy & Astrophysics |volume=642 |pages=A152 |bibcode=2020A&A...642A.152K |s2cid=221319788 }}</ref>
== Evolution == The companion of this system was captured a few hundred years ago, for example when the red giant reached its critical size. It spiralled towards the red giant but stopped before it merged with the core of the primary. During this stage the outer layers of the red giant were ejected. During the [[common envelope]] phase the red giant phase of the primary was terminated and the core was revealed.<ref name="Olofsson et al"/> Later, the bipolar jets formed and met the ejected material, forming the hourglass-shaped structure.<ref name="ALMA press"/> Ejected material shows prominent spectral features of magnesium,<ref>[https://www.aanda.org/articles/aa/abs/2021/07/aa40537-21/aa40537-21.html Heavy-element Rydberg transition line emission from the post-giant-evolution star HD 101584]</ref> while outer ejected structures contain [[methanol]] and [[formaldehyde]].<ref>{{citation|arxiv=2101.06179|year=2021|title=Complex organic molecules in protoplanetary disks: X-ray photodesorption from methanol-containing ices|doi=10.1051/0004-6361/202039676 |last1=Basalgète |first1=R. |last2=Dupuy |first2=R. |last3=Féraud |first3=G. |last4=Romanzin |first4=C. |last5=Philippe |first5=L. |last6=Michaut |first6=X. |last7=Michoud |first7=J. |last8=Amiaud |first8=L. |last9=Lafosse |first9=A. |last10=Fillion |first10=J.-H. |last11=Bertin |first11=M. |journal=Astronomy & Astrophysics |volume=647 |pages=A35 |s2cid=231627611 }}</ref> {{clear left}} == References == {{Reflist}}
{{Stars of Centaurus}}
[[Category:Binary stars]] [[Category:Protoplanetary nebulae]] [[Category:Objects with variable star designations|Centauri, V885]] [[Category:Hipparcos objects|046992]] [[Category:IRAS catalogue objects|11385−5517]] [[Category:A-type supergiants]] [[Category:Variable stars]] [[Category:Henry Draper Catalogue objects|101584]] [[Category:Centaurus]]