Astronomy news always seems to break over coffee, on laptop startup. That was the case Wednesday morning, when word of a curious new object started flashing across the message boards.
The object in question is currently at +18th magnitude, moving slowly along the border of the constellations Serpens Cauda and Sagittarius, right near the galactic plane. The object was captured on July 2nd by the Deep Random Survey remote telescope in Chile. The Asteroid Terrestrial-impact Last Alert System (ATLAS) based in Rio Hurtado made the discovery on July 1st. Sam Deen soon backed this up with pre-discovery images from worldwide ATLAS sites in Chile, Hawaii and South Africa from June 25-29.
The new interstellar object (wider view) candidate A11pl3Z remotely imaged on July 2nd using iTelescope.Net in Chile. Credit: Filipp Romanov.
This allowed astronomers to plot a preliminary orbit. That’s where things get really interesting: the object has an eccentricity now estimated near 6.0—the highest seen yet. An eccentricity of 1.0 or lower is a closed orbit, signifying an asteroid or comet on an elliptical orbit in our solar system. This one is coming from interstellar space on a high inclination 175 degree orbit, perhaps originating from the thin galactic disk.
David Rankin of the University of Arizona’s Catalina sky survey notes on Blue Sky that this high eccentricity cinches the hyperbolic orbit of the object.
Credit: @Astrafoxen (on Blue Sky)/K Ly/Deep Random Survey. Click here for the animation.
Right now, the object isn’t showing any signs of cometary activity. Estimates by Marshall Eubanks (Asteroid Initiatives) suggests it may be an asteroid about 20 kilometers in size.
The object has a preliminary designation on the Near Earth Object Confirmation Page (NEOCP) as A11pl3Z. There should be a formal name within a day or so, and the object will receive an ‘I’ designation for interstellar.
"It (A11pl3Z) is moving very fast, with a velocity about 60 kilometers per second. It may be considerably larger," Eubanks told Universe Today. "1I seems to be a young object, as it was moving near the local galactic 'standard of rest'... by the same token, 3I is probably much older, probably comparable in age to the solar system."
The European Space Agency confirmed the discovery on Blue Sky:
ESA's announcement for A11pl3Z on Blue Sky.
The tale of Oumuamua and Borisov sets the precedent for the discovery. I1/2017 U1 ʻOumuamua was the first interstellar object discovered in 2017. That one was discovered on its outbound leg out of the solar system, sending astronomers scrambling to make observations before it faded from sight. Oumuamua also generated a fair amount of controversy, due to its inferred pancake shape, and its approach from what’s known as the galactic ‘local standard of rest,’ the reference frame that defines the motion of local stars around the galactic center. A fast mover, I1/Oumuamua was moving much too fast to chase down, although proposals were made.
The orbit of A11pl3Z through the inner solar system. Credit: the Catalina Sky Survey.
The discovery of 2019 2I/2019 Q4 Borisov added to our small inventory of known interstellar objects.
A11pl3Z could prove different. First, it's still inbound, currently just inside the orbit of Jupiter. The object reaches perihelion in a few months on October 29th, 2025 at about 1.35 Astronomical Units (AUs) from the Sun, exterior to the orbit of Mars. Intriguingly, A11pl3Z passes just 0.2 AU from Mars on October 3rd, and assets including Mars Reconnaissance Orbiter may be able to nab it as an +11th magnitude object. Unfortunately, Earth will be on the opposite side of the Sun versus the object at perihelion. Closest Earth approach for the object occurs on October 30th, 2025, at 1.35 AU. Moving at 61 kilometers per second outbound, A11pl3Z will be moving much too fast for spacecraft to chase down.
But more crucially, we now have the James Webb Space Telescope and the recently commissioned Vera C. Rubin observatory on hand to bring to bear on A11pl3Z. Vera C. Rubin discovered an amazing 2,104 new asteroids on its very first time out.
Clearly, interstellar asteroids and comets are more common than were previously thought… we were simply missing most of them as they whiz through the solar system. We’ll provide updates as the situation unfolds, and more is known about the enigmatic object A11pl3Z.
Be sure to check out the newly discovered object A11pl32 live tomorrow night starting at 22:00UT/6:00PM EDT, courtesy of astronomer Gianluca Masi and the Virtual Telescope Project.
