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 Scorpiusconstellation 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 Waygalaxy. 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]
