Pulses of dust on an almost unfathomable scale have been ascribed to dramatic dips in the brightness of a star pair, illustrating once again that the cosmos includes things weirder than we can conceive — until we find them. We do not know what is causing this, but citizens of the southern hemisphere with medium-sized telescopes could help us figure it out. The Kepler and TESS space telescopes were designed to look for planets by looking for dips in the brightness of stars as objects pass in front of them.
They have succeeded to a fantastic degree, but they have also discovered certain brightness fluctuations that are too enormous or irregular to be explained by any planet – most notably, KIC 8462852, which was formerly thought to block by a “megastructure.” The most recent example is a pair of stars known as TIC 400799224 until something more memorable discovered both somewhat more massive than our Sun.
A team of professional and citizen scientists report in The Astronomical Journal that one of TIC 400799224’s stars is experiencing brightness dips on a 20-day cycle, but the unpredictability of the dips signals something extremely sophisticated is occurring. Citizen scientists initially observed a dramatic decline in the brightness of TIC 400799224, which drew the attention of astronomers. Following up with a professional indicated that around a fourth of the overall light was blocked.
Three overlapping dips, rather than a single smooth fading, suggested “a very irregular occulting body,” according to the article. When TESS’ observations are combined with archive data from other sensors, a 19.77-day cycle emerges. Anything strange in binary systems is frequently considered to cause by interactions between the stars. The stars in TIC 400799224, on the other hand, are around 300 astronomical units apart, which is 10 times the distance between the Sun and Neptune. Any impacts would be too little and sluggish to explain something like this at that distance.
Despite the enormous gap, TESS’ picture resolution is insufficient to tell which star is sinking, especially given their comparable brightness. The measured 25% decrease in overall brightness translates to a loss of either 37% of the light from the larger star or an unprecedented 75% of the light from the fainter one. The most perplexing feature is that “although the occultations appear to have a tight underlying time, they are unpredictable in form, depth, and length,” according to the research. The majority of the time, no dip can see at all.
The stars TIC 400799224 and KIC 8462852 are not the only ones that have brightness dips that are too great to explain by planets. KIC-1520 was identified to be on a 15.6-hour cycle in 2012 and subsequently described as caused by a massive dust cloud formed by a tiny and close-in planet collapsing. The brilliance of the star dimmed substantially every time a planet or cloud passed between it and us. Since then, several more stars have been explained in the same way. All of these stars, however, are significantly fainter and less massive than TIC 400799224, with much smaller and more frequent dips.
The fact that TIC 400799224 is generating significantly more radiation, which should disturb neighboring dust, makes its presence even more astonishing. Ceres would disintegrate completely in 8,000 years if it emitted this much dust – a blink of an eye for a star system like this.
The authors confess they do not know what forces might kill such an asteroid, among other things. However, if you are curious, you might be able to assist. TIC 400799224 is bright enough to seen in big backyard telescopes at magnitude 12.6. Regular amateur observations may enhance professional data to follow its changes, much as citizen scientists alerted astronomers to it. However, it is too far south to be visible from northern latitudes.
