Erika

In this way, the new radio detection offers a compelling piece of evidence that 3I/ATLAS is a bona-fide interstellar comet, a visitor from beyond our Solar System behaving in line with our known cometary physics. 9/9

Further monitoring will help clarify whether the hydroxyl production is steady or variable, how extended the gas tail is, and how the object’s trajectory responds to non-gravitational forces. 8/

The observations were made on 24 October, shortly before the object’s perihelion, and after earlier unsuccessful attempts on 20 and 28 September. 7/

Although the detection alone does not shut down every alternative hypothesis, it significantly reduces the plausibility of a “probe” interpretation and underscores the comet-like nature of 3I/ATLAS. 6/

Earlier speculations had entertained the possibility of technological origin, fanned by social-media theories and even proposals by controversial astrophysicist Avi Loeb, but this molecular signature strongly tilts the balance toward a natural origin. 4/

Because 3I/ATLAS was approaching its closest point to the Sun, the geometry favored absorption of radio signals rather than emission, matching expected behaviour of an active comet rather than a transmitter. 3/

The signal consists of absorption lines of hydroxyl radicals (OH) at 1665 MHz and 1667 MHz, molecules commonly found when icy bodies near the Sun sublimate and generate a gaseous coma. 2/

Astronomers using the South African radio telescope array MeerKAT have detected a clear radio-frequency signal from the interstellar object #3I/ATLAS, bringing strong support to the idea that it is a natural comet rather than an artificial object. 1/

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... (which will eventually survey ~20 billion galaxies) will systematically reveal a rich archaeological record of galaxy formation. 5/5

... namely its unusually high star-formation rate and multiple supernovae.

The discovery underscores that such stellar streams are likely ubiquitous around large galaxies and that Rubin’s unprecedented wide-field, deep-imaging camera... 4/

Astronomers interpret this as the shredded remnant of a dwarf galaxy that M61’s gravity ripped apart: this ancient encounter may have triggered fresh bursts of star formation in M61 and explains some of the galaxy’s puzzling properties, ... 3/

... and revealed for the first time a faint but very long stellar stream, a “tail” stretching about 55 kiloparsecs (≈180,000 light-years)—that had gone unnoticed despite decades of study. 2/

The @VRubinObs has already unveiled a stunning discovery: in its very first test image the giant telescope captured the well-known galaxy Messier 61 (M61), located in the Virgo cluster, ... 1/

#science #news #astronomy

👉 arxiv.org/pdf/2510.24836

These fresh observations highlight just how much we still don’t know about interstellar objects. 7/7

Though such behavior is not unheard of for comets, 3I/ATLAS nevertheless remains unusual: it shares comet-like activity while originating from outside our Solar System, and its composition and behaviour may inform us about conditions in another part of the galaxy. 6/

Concurrently, the object brightened significantly, by a factor of about five in the green band, which supports the idea that volatile release or fragmentation is ongoing. 5/

Based on the measured accelerations, the mass loss could amount to about 13 percent (or more) of the body’s total mass, assuming a typical gas-ejection speed near perihelion. 4/

... both radially and tangentially relative to the Sun.

The most plausible explanation is that 3I/ATLAS has been losing mass via outgassing, volatiles liberated by solar heating exert a thrust that nudges its path. 3/

While briefly hidden from view behind the Sun, it was monitored by spacecraft near Mars, and when it emerged, astronomers observed that its trajectory has shifted in a way that cannot be explained by gravity alone: the object shows non-gravitational acceleration ... 2/

The object known as #3I/ATLAS, the third confirmed interstellar visitor to our Solar System, appears to have undergone a subtle but telling transformation following its closest approach to the Sun. 1/

... recently observed for 3I/ATLAS, C/2025 K1 is now visible with a good telescope or binoculars in the constellations of Virgo and Leo before dawn, at least through early December. 6/6

They also suggest that its extreme proximity to the Sun and its relatively low gas-to-dust ratio may have contributed to the effect. With an apparent magnitude near 9, the same brightness ... 5/

Astronomers believe this peculiar hue is due to a remarkable scarcity of carbon-bearing molecules such as dicarbon, carbon monoxide, and cyanide, which altered the reflected colors of its gases and dust. 4/

Against all odds, it survived its perilous perihelion and reemerged with a striking golden-reddish-brown glow in its coma and tail, a highly unusual color for comets. 3/

... overshadowed by the famous interstellar visitor 3I/ATLAS.

However, around October 8, as it passed just 50 million kilometers from the Sun, four times closer than the other ATLAS, it seemed doomed to disintegrate. 2/

The recently discovered object known as C/2025 K1 (ATLAS) has become an unexpected attraction. Found in May by the Asteroid Terrestrial-impact Last Alert System (ATLAS), this comet initially drew little attention, ...1/

👉 www.astronomerstelegram.org?read=17362

Image credit: Dan Bartlett

Ultimately, this means future instruments could not only show black holes in greater detail but crucially test whether they all follow the “standard” relativistic type or if there exist fundamentally different black-hole classes with distinct signatures. 5/5

... and shape which would become detectable once the angular resolution drops below roughly one millionth of an arc-second (comparable to viewing a coin on the Moon). 4/

Their results show that although current telescopic resolution (such as that of the Event Horizon Telescope) still cannot discriminate among many of the exotic possibilities, the deviations from Einstein’s black‐hole solution produce systematic imprints in the shadow radius ... 3/

By running detailed 3D simulations of hot plasma and magnetic fields swirling near a black hole’s event horizon, they generated “shadow” images of what these objects would look like under different theoretical frameworks. 2/