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VVV-WIT-07

Coordinates: Sky map 17h 26m 29.387s, −35° 40′ 56.20″
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VVV-WIT-07

Context star field of
VVV-WIT-07
Observation data
Epoch J2000      Equinox J2000
Constellation Scorpius
Right ascension 17h 26m 29.387s[1]
Declination −35° 40′ 56.20″[1]
Astrometry
Proper motion (μ) RA: 2.469[1] mas/yr
Dec.: 1.374[1] mas/yr
Parallax (π)2.5190 ± 1.1187 mas[2]
Distanceapprox. 1,300 ly
(approx. 400 pc)
Other designations
Gaia DR2 5974962995291907584[1]
Database references
SIMBADdata

VVV-WIT-07 is a unique variable star which presents a sequence of recurrent dimmings (Ks~14.35 – 16.164)[1] with a possible deep eclipse in July 2012. The star, located in the Scorpius constellation about 23,000 ly (7,100 pc) away,[1] is not a binary star, which would eliminate such a system from explaining the various observed dimmings.[3]

Overview

A light curve for VVV-WIT-07, adapted from Saito et al. (2019).[1] The inset plot shows the July 2012 dimming event with an expanded scale.

The star was found by the "Vista Variables in the Via Lactea" (VVV) project, which is a survey of European Southern Observatory (ESO) variability of the innermost bulge of the Milky Way galaxy. The near-infrared spectra of VVV-WIT-07 appear without features, without prominent emission or absorption lines. The characteristics found in the light curve of VVV-WIT-07 (WIT refers to "What Is This?") are similar to those seen in J1407 (Mamajek's Object), a pre-MS K5 dwarf with a ring system that eclipses the star or, alternatively, to Tabby's star, an F3 IV/V star that shows irregular and aperiodic obscurations in its light curve.[1][4][5][6][7][8][3]

From 2010 to 2018, the star dimmed and brightened irregularly (v~14.35 – 16.164),[1] and seemed similar to Tabby's star, except the light from VVV-WIT-07 dimmed by up to 80 percent, while Tabby's star faded by only about 20 percent.[8] Another star, J1407, however, has been found to have dimmed by up to 95%, which may be more similar to the light curve presented by VVV-WIT-07.[8] Nonetheless, according to ESO astronomer Valentin Ivanov, "A key word that could be used to describe our finding [of VVV-WIT-07] is extreme. In every aspect ... We have identified a system that challenges the imagination even more than usual, because it is so unlike our own planetary system."[3]

See also

References

  1. ^ a b c d e f g h i j Saito, Roberto K.; et al. (2019). "VVV-WIT-07: another Boyajian's star or a Mamajek's object?". Monthly Notices of the Royal Astronomical Society. 482 (4): 5000–5006. arXiv:1811.02265. Bibcode:2019MNRAS.482.5000S. doi:10.1093/mnras/sty3004. S2CID 119068259.
  2. ^ Brown, A. G. A.; et al. (Gaia collaboration) (2021). "Gaia Early Data Release 3: Summary of the contents and survey properties". Astronomy & Astrophysics. 649: A1. arXiv:2012.01533. Bibcode:2021A&A...649A...1G. doi:10.1051/0004-6361/202039657. S2CID 227254300. (Erratum: doi:10.1051/0004-6361/202039657e). Gaia EDR3 record for this source at VizieR.
  3. ^ a b c Ivanov, Valentin D. (22 March 2019). "What Is This? - Astronomers discover mysterious star displaying never-seen-before behaviour". European Southern Observatory. Retrieved 9 June 2019.
  4. ^ Saito, R.K.; et al. (6 November 2018). "VVV-WIT-07: another Boyajian's star or a Mamajek's object?". Monthly Notices of the Royal Astronomical Society. 482 (4): 5000–5006. arXiv:1811.02265. Bibcode:2019MNRAS.482.5000S. doi:10.1093/mnras/sty3004. S2CID 119068259.
  5. ^ Seidel, Jamie (23 November 2018). "VVV-WIT-07: This ancient, erratic star hides a dark secret". The Advertiser. Retrieved 8 June 2019.
  6. ^ Anderson, Paul Scott (29 November 2018). "Have astronomers found another Tabby's Star? - Remember when astronomers found Tabby's Star and said they'd never seen anything like it? Now there's another one … maybe". Earth & Sky. Retrieved 8 June 2019.
  7. ^ Redd, Nola Taylor (21 November 2018). "Have Astronomers Found Another "Alien Megastructure" Star? - Scientists now have a second example of a strange stellar phenomenon speculatively linked to extraterrestrial intelligence in 2015". Scientific American. Retrieved 8 June 2019.
  8. ^ a b c Grossman, Lisa (22 December 2018). "Astronomers spot another star that flickers like Tabby's star - It's unclear what's causing the newly discovered object to blink, but it's probably not aliens". Science News. Vol. 194, no. 12. p. 9. Retrieved 8 June 2019.
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