V915 Scorpii

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V915 Scorpii (HR 6392, HD 155603) is a hypergiant and semiregular variable star, located Template:Convert away in the constellation Scorpius. Its apparent magnitude varies between 6.22 and 6.64, being heavily diminshed by 2.93 magnitudes due to interstellar extinction. When it is at its brightest, it is very faintly visible to the naked eye under excellent observing conditions.

Surroundings

V915 Scorpii and its companions resolved by the Hubble Space Telescope

V915 Scorpii is surrounded by the sparse OB association Moffat 2.[1] It is also surrounded by an envelope of dust and gas, producing a significant infrared excess.[2]

V915 Scorpii has been classified as a triple star. 15" away is the Wolf-Rayet star WR 85, one of the most luminous stars known, but still visually four magnitudes fainter than V915 Scorpii.[3] Component C is a 10th magnitude K class star 17" away.[4] There is also a 14th magnitude star 22" away. Photometry and space motions suggest that only V915 Scorpii and WR 85 lie at the same distance, while the other two stars are foreground objects. Assumptions about the brightness of each star suggest a distance of Template:Val, and a projected separation of Template:Val.[5]

Four arc minutes distant are two other assumed members of the association, a 10th magnitude B0 giant and an 11th magnitude OB star. Fitting the association members to a main sequence gives a highly uncertain distance of 1.8 kpc.[1] A kinematical distance has been calculated for the bubble around WR 85 at 2.8 kpc.[6] The distance to V915 Scorpii derived assuming minimal interstellar extinction is Template:Val.[2] However, the star is considerably reddened and this results in a distance of Template:Val.[5] Analysis of WR 85 as a luminous hydrogen-rich star gives a distance of Template:Val.[3] Bailer-Jones et al. 2018 estimates a distance of 1,720 pc.[7] The parallax for WR 85 is considerably reliable and suggests a distance of around Template:Val.[8]

Variability

A light curve for V915 Scorpii, plotted from Hipparcos data[9]

V915 Scorpii is classified as a semiregular variable, with an apparent magnitude that varies between 6.22 and 6.64.[10] Any period associated with the variation is longer than 600 days.[11]

The variability of V915 Scorpii was first announced by the Konkoly Observatory in 1979. It was given the variable-star designation V915 Scorpii in 1978.[12]

Properties

V915 Scorpii has a spectral classification of Template:Nowrap,[13] meaning that it is a massive, hypergiant star. It has a mass estimated at 8.5[14] or 14.7[15] times the mass of the Sun, while its radius is of Template:Solar radius, thus giving a volume equivalent to about 330 million times that of the Sun.[16] V915 Scorpii is radiating a luminosity equivalent to 74,000[14] or 185,000[17] times the solar luminosity and has a surface effective temperature of 4,600Template:NbspK,[16] giving it the typical orange color of a K-type star.[18]

The spectral type of V915 Scorpii was determined to be G5Ia in 1954,[19] G5Ia-0 in 1973,[20] G8Ia in 1977,[1] K0Ia in 1982,[21] and K0Ia-0 in 1989,[22] all indicative of a luminous supergiant or hypergiant.

See also

Notes

Template:Notelist

References

Template:Reflist

Template:Stars of Scorpius

  1. ↑ 1.0 1.1 1.2 Cite error: Invalid <ref> tag; no text was provided for refs named moffat
  2. ↑ 2.0 2.1 Cite error: Invalid <ref> tag; no text was provided for refs named odenwald
  3. ↑ 3.0 3.1 Cite error: Invalid <ref> tag; no text was provided for refs named hamann
  4. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named wds
  5. ↑ 5.0 5.1 Cite error: Invalid <ref> tag; no text was provided for refs named andrews
  6. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named vasquez
  7. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named b-h
  8. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named dr3wr85
  9. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named HipDataAccess
  10. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named aavso
  11. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named tycho
  12. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named ibvs
  13. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named simbad
  14. ↑ 14.0 14.1 Cite error: Invalid <ref> tag; no text was provided for refs named starhorse
  15. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named kervela
  16. ↑ 16.0 16.1 Cite error: Invalid <ref> tag; no text was provided for refs named dr3
  17. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named geogebra
  18. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named atnf
  19. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named bidelman
  20. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named warren
  21. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named michigan
  22. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named perkins
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