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KX Andromedae

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KX Andromedae

Bipolar jets ejected from KX Andromedae, imaged in emission lines of sulfur, hydrogen, and oxygen
Observation data
Epoch J2000      Equinox J2000
Constellation Andromeda
Right ascension 23h 07m 06.21216s[1]
Declination +50° 11′ 32.4886″[1]
Apparent magnitude (V) 6.88 – 7.28 variable[2]
Characteristics
Spectral type B3pe+K1III[3]
Apparent magnitude (U) 6.79[4]
Apparent magnitude (B) 7.25[4]
Apparent magnitude (V) 6.92[4]
Apparent magnitude (G) 6.852[1]
Apparent magnitude (J) 5.845[5]
Apparent magnitude (H) 5.33[4]
Apparent magnitude (K) 5.19[4]
Variable type Be star
Astrometry
Radial velocity (Rv)−7.8±0.9[6] km/s
Proper motion (μ) RA: +1.625(19) mas/yr[1]
Dec.: −0.761(17) mas/yr[1]
Parallax (π)1.3172±0.0207 mas[1]
Distance2,480 ± 40 ly
(760 ± 10 pc)
Orbit[7]
Period (P)38.919 days
Eccentricity (e)0±0.03
Inclination (i)50±5°
Periastron epoch (T)HJD 2423220.25±0.09
Semi-amplitude (K2)
(secondary)		86.2±0.8 km/s
Details
Primary
Mass9.0±0.1[8] M☉
Age22.4±3.1[8] Myr
Secondary
Radius19±4[7] R☉
Surface gravity (log g)2.0±0.5[7] cgs
Temperature5000±400[7] K
Rotational velocity (v sin i)25±5[7] km/s
Other designations
KX And, AAVSO 2302+49, BD+49 4045, HD 218393, HIP 114154, SAO 52701, TYC 3631-1533-1, 2MASS J23070621+5011324
Database references
SIMBADdata

KX Andromedae (often abbreviated to KX And) is a spectroscopic binary star in the constellation Andromeda. Its apparent visual magnitude varies between 6.88 and 7.28.[2] It is at a distance of 2,480 light-years (760 parsecs).[1]

A light curve for KX Andromedae, plotted from Hipparcos data,[9] folded with the period published by Koen and Eyer (2002)[10]

The primary component of the KX Andromedae system is a Be star with a spectral classification B3pe as of 2017,[2] although in historical records it has varied from B1 to B7.[11]

The secondary star is difficult to detect in the spectrum, but has been given a K1III spectral type. It is likely to be an asymptotic giant branch star that fills its Roche lobe, transferring mass to the primary star.[7]

The system is only about 25 million years old. The pair complete a circular orbit every 38.919 days at an inclination of 50°.[7]

KX Andromedae is surrounded by bipolar jets of ejected material, that extend 19 light-years (5.8 parsecs) out from it in each direction (angular size 20′). These faint jets were discovered in hydrogen-alpha emission in 2024 by astronomer Stefan Ziegenbalg. Subsequent studies in other emission lines revealed a more complex structure (see image): the jets were detected only in singly ionized sulfur and hydrogen, while an outer shell is also visible in doubly ionized oxygen. This suggests the presence of different ionization mechanisms. The shell may be visible as a result of shock ionization of the surrounding interstellar medium, whereas the gas within the jets may be ionized by the B3pe component of KX Andromedae, which likely does not emit sufficient energy to doubly ionize oxygen.[12]

References

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  1. ^ a b c d e f Vallenari, A.; et al. (Gaia collaboration) (2023). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy and Astrophysics. 674: A1. arXiv:2208.00211. Bibcode:2023A&A...674A...1G. doi:10.1051/0004-6361/202243940. S2CID 244398875. Gaia DR3 record for this source at VizieR.
  2. ^ a b c KX And, database entry, Combined General Catalog of Variable Stars (GCVS5.1, 2017 Ed.), N. N. Samus, O. V. Durlevich, et al., CDS ID II/250 Accessed on line 2018-10-17.
  3. ^ Shenavrin, V. I.; Taranova, O. G.; Nadzhip, A. E. (2011). "Search for and study of hot circumstellar dust envelopes". Astronomy Reports. 55 (1): 31–81. Bibcode:2011ARep...55...31S. doi:10.1134/S1063772911010070. S2CID 122700080.
  4. ^ a b c d e Database entry, Catalogue of Stellar Photometry in Johnson's 11-color system (2002 Ed.), J. R. Ducati, CDS ID II/237 Accessed on line 2018-11-10.
  5. ^ Cutri, Roc M.; Skrutskie, Michael F.; Van Dyk, Schuyler D.; Beichman, Charles A.; Carpenter, John M.; Chester, Thomas; Cambresy, Laurent; Evans, Tracey E.; Fowler, John W.; Gizis, John E.; Howard, Elizabeth V.; Huchra, John P.; Jarrett, Thomas H.; Kopan, Eugene L.; Kirkpatrick, J. Davy; Light, Robert M.; Marsh, Kenneth A.; McCallon, Howard L.; Schneider, Stephen E.; Stiening, Rae; Sykes, Matthew J.; Weinberg, Martin D.; Wheaton, William A.; Wheelock, Sherry L.; Zacarias, N. (2003). "VizieR Online Data Catalog: 2MASS All-Sky Catalog of Point Sources (Cutri+ 2003)". CDS/ADC Collection of Electronic Catalogues. 2246: II/246. Bibcode:2003yCat.2246....0C.
  6. ^ Pourbaix, D.; et al. (September 2004). "SB9: The ninth catalogue of spectroscopic binary orbits". Astronomy and Astrophysics. 424 (2): 727–732. arXiv:astro-ph/0406573. Bibcode:2004A&A...424..727P. doi:10.1051/0004-6361:20041213. S2CID 119387088.{{cite journal}}: CS1 maint: postscript (link)
  7. ^ a b c d e f g Tarasov, A. E.; Berdyugina, S. V.; Berdyugin, A. V. (May 1998). "The massive interacting binary KX And: The orbit and physical parameters of the secondary component". Astronomy Letters. 24 (3): 316–320. Bibcode:1998AstL...24..316T.
  8. ^ a b Tezlaff, N.; Neuhäuser, R.; Hohle, N. N. (January 2011). "A catalogue of young runaway Hipparcos stars within 3 kpc from the Sun". Monthly Notices of the Royal Astronomical Society. 410 (1): 190–200. arXiv:1007.4883. Bibcode:2011MNRAS.410..190T. doi:10.1111/j.1365-2966.2010.17434.x. S2CID 118629873.
  9. ^ "/ftp/cats/more/HIP/cdroms/cats". Centre de Données astronomiques de Strasbourg. Strasbourg astronomical Data Center. Retrieved 15 October 2022.
  10. ^ Koen, Chris; Eyer, Laurent (March 2002). "New periodic variables from the Hipparcos epoch photometry". Monthly Notices of the Royal Astronomical Society. 331 (1): 45–59. arXiv:astro-ph/0112194. Bibcode:2002MNRAS.331...45K. doi:10.1046/j.1365-8711.2002.05150.x.
  11. ^ Koubský, P.; Harmanec, P.; Brož, M.; Kotková, L.; Yang, S.; Božić, H.; Sudar, D.; Frémat, Y.; Korčáková, D.; Votruba, V.; Škoda, P.; Šlechta, M.; Ruždjak, D. (2019). "Properties and nature of Be stars. 31. The binary nature, light variability, physical elements, and emission-line changes of HD 81357". Astronomy and Astrophysics. 629. arXiv:1908.02719. Bibcode:2019A&A...629A.105K. doi:10.1051/0004-6361/201834597.
  12. ^ Ziegenbalg, Stefan (November 2024). "Detection of 19 lt-yr Long Bipolar Jets from Interacting Binary KX And". Research Notes of the AAS. 8 (11): 289. Bibcode:2024RNAAS...8..289Z. doi:10.3847/2515-5172/ad9478.
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