A bright star in the Andromeda galaxy appears to have simply vanished. After a dramatic mid-infrared flare in 2014, the object has faded in visible light by a factor of more than 10,000 by 2023, according to a new peer-reviewed Science paper that triggered a flurry of follow-up work. I want to walk through what astronomers actually saw, what it might mean if a star really blinked out to form a black hole, and why some researchers still think a heavily shrouded survivor could be hiding in the dark.
The Discovery Timeline
The story starts in archival data from WISE and NEOWISE, the infrared sky surveys described in canonical survey papers by Wright and Mainzer and in the NEOWISE Reactivation work labeled as Mainzer Reactivation. According to Official NASA, those missions picked up a mid-infrared brightening in 2014 from a source in Andromeda now known as M31-2014-DS1, which suddenly began radiating strongly at wavelengths where warm dust glows. The peer-reviewed Science analysis identifies that source as a hydrogen-depleted supergiant in Andromeda and argues that this infrared flare was the first sign that something extraordinary was happening.
Years later, a long-term monitoring program with the Large Binocular Telescope, described in the Primary LBT methodology paper, provided the second key piece of the puzzle. That program is designed to catch failed supernova candidates by watching for stars that simply disappear, and it flagged M31-2014-DS1 after optical images showed that the once-luminous star had faded by more than 10,000 times by 2023. A detailed Preprint led by De and colleagues, building on that LBT work, reports that follow-up with JWST confirmed strong molecular absorption features and a surrounding silicate dust shell, indicating that the 2014 outburst expelled material that is now cooling and expanding around whatever remains at the center.
What Happened to the Star?
The peer-reviewed Science paper, cited in the Peer entry for M31-2014-DS1, puts forward a failed supernova as the leading explanation. In that model, a hydrogen-depleted supergiant in Andromeda shed part of its outer layers in a low-energy event that lit up the mid-infrared, but the core then collapsed directly into a stellar-mass black hole without the kind of bright explosion usually associated with a supernova. The Embargo press material tied to the Science DOI frames the claim explicitly as a collapse to a black hole, with the expelled material now forming the dusty cocoon seen by JWST.
Researchers explicitly compare this to the benchmark case of NGC 6946-BH1, a previous “vanishing star” candidate analyzed with HST and other observatories. In that Primary NGC benchmark study, astronomers saw a weak outburst followed by the apparent disappearance of the star in HST images and a fading mid-infrared signal, and modeling argued against a simple dust-shell obscuration. The new Andromeda event, M31-2014-DS1, looks similar enough that the Science authors and the Embargo summary treat NGC 6946-BH1 as a template, extending the idea that some massive stars may quietly form black holes without ever producing a classic supernova.
The Evidence Chain
To support such a dramatic claim, teams have assembled a multi-wavelength evidence chain that starts with the infrared surveys. The Official NASA explainer describes how archival photometry from WISE and NEOWISE captured the 2014 mid-infrared brightening, drawing directly on the Authoritative WISE mission documentation that lists Wright, Mainzer and the NEOWISE Reactivation survey papers as the canonical references. Those data show the star suddenly pumping energy into dust, which then re-radiated in the mid-infrared, while earlier epochs looked quiet.
The Preprint by De and collaborators adds JWST mid-infrared spectroscopy and photometry, revealing molecular absorption bands and silicate dust features that trace the composition and temperature of the expanding shell. That work uses line profiles to estimate expansion velocities and the physical scale of the dust shell, tying them to the timing of the 2014 outburst. At the same time, the same preprint and a Competing analysis both report deep X-ray non-detections from Chandra, setting limits on any accreting black hole or neutron star. LBT optical monitoring, as summarized in the Primary LBT methodology paper and in the Official NASA explainer, shows no optical or ultraviolet recovery after the more than 10,000-fold fade, which is a key reason many astronomers treat the star as effectively gone.
Why This Matters for Astrophysics
The LBT program was designed to test whether failed supernovae exist, and its Primary methodology paper explains how it searches for stars that vanish over years as a way to estimate how often massive stars might quietly collapse. That work, which Supports the new interpretation, argues that such events should be rare, with only a few per galaxy per century, so finding even one strong candidate in Andromeda is a significant development. The Official NASA explainer uses that context to frame M31-2014-DS1 as an important data point for black hole formation rates and the diversity of stellar deaths.
Those stakes are echoed in the EurekAlert Evi press package tied to the Science DOI, where experts describe being surprised by the event rates implied if this object truly collapsed into a black hole without a bright supernova. NASA’s own framing in its NASA explainer emphasizes that linking infrared outbursts, optical disappearances and faint or absent X-ray signatures could reshape how models count black holes in galaxies. If some fraction of massive stars follow this path, then traditional supernova surveys would be missing a hidden population of stellar-mass black holes that formed in near-silence.
Alternative Explanations and Uncertainties
Not everyone is convinced that M31-2014-DS1 has already become a black hole. A Competing preprint argues that a luminous mid-infrared source still persists at the location and can be modeled as a dust-enshrouded star rather than a vanished one, drawing on JWST, SMA and Chandra observations. In that view, the extreme optical fading could be explained by a complex, asymmetric dust geometry that blocks visible light along our line of sight while still allowing infrared emission to escape.
Both the De Preprint and the Competing analysis stress that there is no definitive black hole confirmation, because Chandra has not detected the kind of bright X-ray accretion signal that would settle the case. The Official NASA explainer also notes that the lack of X-rays is a double-edged constraint, since a newly formed black hole might accrete only weakly or intermittently. For now, the field is left with two main possibilities: a failed supernova that left behind a quiet black hole wrapped in dust, or a surviving star that is heavily obscured by a complex dust shell whose geometry is still poorly understood.
Broader Context in Stellar Evolution
M31-2014-DS1 is not the first time astronomers have watched a massive star seem to vanish. The Primary HST benchmark study of NGC 6946-BH1 used HST imaging to show that a once-bright star in another galaxy disappeared after a weak outburst, while mid-infrared emission gradually faded. That work, which treated NGC 6946-BH1 as a benchmark for vanishing star candidates, argued that simple dust obscuration could not easily explain the observations, which is why the new Andromeda case is so often compared to it in the Science paper and Embargo materials.
These events also highlight how critical archival surveys are for catching rare transitions in stellar evolution. The Authoritative NEOWISE portal details how WISE and NEOWISE operated in multiple phases, with survey data products tied to Wright, Mainzer and the NEOWISE Reactivation work, and those long-running observations made it possible to spot the 2014 mid-infrared flare years after it happened. As coverage in Scientific American and other Major outlets has stressed, combining such archives with targeted programs like LBT and sensitive observatories like JWST and Chandra is now giving astronomers a way to watch how some of the universe’s most massive stars meet their end, whether in a blaze of light or in a quiet, almost invisible collapse.
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*This article was researched with the help of AI, with human editors creating the final content.
