HD 101584 seen byALMA. 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. Acknowledgement: Robert Cumming
Alight curve for V885 Centauri, plotted fromHipparcos data[6]
In 1991, Jean Manfroidet al. publishedphotometry that showed that HD 101584 is avariable star.[7]HD 101584 has been given thevariable 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.[8] However Koen and Eyer detected, in the star'sHipparcos data, an oscillation of the star's brightness with a period of 6.744 days and an amplitude of only 0.02 magnitudes.[9]
HD 101584 and the surrounding nebula, seen byHubble
TheHubble Space Telescope image shows a diffusecircumstellar environment with a circular ring around HD 101584.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 150km/s and is inclined to the line of sight by10+10 −5°. There is evidence for a second bipolar outflow with a different orientation from the major outflow.[3] The inner disk, heated to 1540K, currently has been sublimated by the increasing luminosity of the star.[10]
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 thecommon envelope phase the red giant phase of the primary was terminated and the core was revealed.[3] Later, the bipolar jets formed and met the ejected material, forming the hourglass-shaped structure.[5] Ejected material shows prominent spectral features of magnesium,[11] while outer ejected structures containmethanol andformaldehyde.[12]
^Olofsson, H.; Black, J. H.; Khouri, T.; Vlemmings, W. H. T.; Humphreys, E. M. L.; Lindqvist, M.; Maercker, M.; Nyman, L.; Ramstedt, S.; Tafoya, D. (2021). "Heavy-element Rydberg transition line emission from the post-giant-evolution star HD 101584".Astronomy and Astrophysics.651: A35.arXiv:2105.00699.Bibcode:2021A&A...651A..35O.doi:10.1051/0004-6361/202140537.S2CID233481052.
^"/ftp/cats/more/HIP/cdroms/cats".Centre de Données astronomiques de Strasbourg. Strasbourg astronomical Data Center. Retrieved15 October 2022.
^Manfroid, J.; Sterken, C.; Bruch, A.; Burger, M.; de Groot, M.; Duerbeck, H. W.; Duemmler, R.; Figer, A.; Hageman, T.; Hensberge, H.; Jorissen, A.; Madejsky, R.; Mandel, H.; Ott, H. A.; Reitermann, A.; Schulte-Ladbeck, R. E.; Stahl, O.; Steenman, H.; Vander Linden, D.; Zickgraf, F. J. (March 1991)."Long-term photometry of variables at ESO. I. The first data catalogue (1982-1986)".Astronomy and Astrophysics, Suppl. Ser.87:481–498.Bibcode:1991A&AS...87..481M. Retrieved20 January 2025.
^"V0885 Cen".The International Variable Star Index. AAVSO. Retrieved21 October 2022.
^Kluska, J.; Olofsson, H.; Van Winckel, H.; Khouri, T.; Wittkowski, M.; De Wit, W. J.; Humphreys, E. M. L.; Lindqvist, M.; Maercker, M.; Ramstedt, S.; Tafoya, D.; Vlemmings, W. H. T. (2020), "VLTI/PIONIER reveals the close environment of the evolved system HD 101584",Astronomy & Astrophysics,642: A152,arXiv:2008.11555,Bibcode:2020A&A...642A.152K,doi:10.1051/0004-6361/202037946,S2CID221319788
