Whereas engaged on a bit about interstellar migration as a response to the accelerating growth of the universe for subsequent week, I wish to pause a second on a simply introduced statement. I’ve at all times had a fascination with the Magellanics, these satellite tv for pc galaxies which can be so helpful to astronomers as a result of their gravitational interactions with the Milky Approach render each of them irregular in form. That triggers waves of star formation and tells us one thing about how galaxies assemble themselves. The Small Magellanic Cloud (SMC), about 200,000 gentle years away, exhibits little construction, whereas the Giant Magellanic (LMC) is a little more organized however lacks symmetry – no clean disk obvious there.
Picture: This stunning picture taken at ESO’s Paranal Observatory exhibits the 4 Auxiliary Telescopes of the Very Giant Telescope (VLT) Array, set in opposition to an extremely starry backdrop on Cerro Paranal in Chile. The Auxiliary Telescopes are every 1.8 metres in diameter and work with the 4 8.2-metre diameter Unit Telescopes to make up the world’s most superior optical observatory. The telescopes work collectively to type the VLT Interferometer (VLTI), a large interferometer which permits astronomers to see particulars as much as 25 occasions finer than can be doable with the person Unit Telescopes. Hanging over the location are the distinguished Small and Giant Magellanic Clouds, seen solely within the southern sky. These two irregular dwarf galaxies are within the Native Group and so are companion galaxies to our personal galaxy, the Milky Approach. The picture was taken by John Colosimo, who submitted it to the Your ESO Photos Flickr group. Credit score: ESO/J. Colosimo.
Inside the LMC, some 160,000 gentle years away, astronomers have simply imaged a quickly evolving star, an interesting catch as a result of the article is dying and we apparently see it simply earlier than a supernova occasion. The telltale signal is the huge ejection of stellar materials. The work was performed with the European Southern Observatory’s Very Giant Telescope Interferometer (VLTI), which mixes the sunshine collected by 4 telescopes, utilizing the GRAVITY interferometer, correcting for atmospheric turbulence and offering imaging at four-milliarcsecond decision. The impact is to provide the spatial decision of a telescope of as much as 130 meters in diameter relying on path within the sky.
Lengthy-studied and generally known as the ‘behemoth star,’ WOH G64 has proven shocking modifications over a comparatively quick time period. Keiichi Ohnaka (Universidad Andrés Bello, Chile) describes a star that’s blowing out fuel and dirt within the final phases of its progress towards turning into a supernova: “We found an egg-shaped cocoon carefully surrounding the star. We’re excited as a result of this can be associated to the drastic ejection of fabric from the dying star earlier than a supernova explosion.” Co-author Jacco van Loon (Keele College, UK) provides: “This star is likely one of the most excessive of its type, and any drastic change might carry it nearer to an explosive finish.”
Shedding their outer layers, a pink supergiant might take hundreds of years to lose materials earlier than a supernova truly happens. In line with the paper, pink supergiants like WOH G64 expertise mass loss charges as excessive as ∼10−4 M☉ yr−1 — which means the star at this stage is dropping on the order of 0.0001 photo voltaic plenty of fabric yearly. Current work on different supernovae inform us that the mass-loss fee will increase considerably simply earlier than the supernova occasion. It’s additionally intriguing that some pink supergiants at this level of growth present mass loss that’s not symmetric. So far as I can discover, the reason is that the star is probably going interacting with a binary companion. And certainly the paper notes:
The compact emission imaged with GRAVITY and the near-infrared spectral change counsel the formation of scorching new mud near the star, which provides rise to the monotonically rising near-infrared continuum and the excessive obscuration of the central star. The elongation of the emission could also be because of the presence of a bipolar outflow or results of an unseen companion.
Picture: Positioned within the Giant Magellanic Cloud, at a staggering distance of over 160 000 light-years from us, WOH G64 is a dying star roughly 2000 occasions the dimensions of the Solar. This picture of the star (left) is the primary close-up image of a star outdoors our galaxy. This breakthrough was doable due to the European Southern Observatory’s Very Giant Telescope Interferometer (ESO’s VLTI), positioned in Chile. The brand new picture, taken with the VLTI’s GRAVITY instrument, exhibits that the star is enveloped in a big egg-shaped mud cocoon. The picture on the best exhibits an artist’s impression reconstructing the geometry of the buildings across the star, together with the intense oval envelope and a fainter dusty torus. Confirming the presence and form of this torus would require further observations. Credit score: ESO/Ok. Ohnaka et al., L. Calçada.
I think that Centauri Goals readers will bear in mind the Giant Magellanic Cloud because the obvious subsequent vacation spot of the interstellar interloper Rama in Arthur C. Clarke’s Rendezvous with Rama (1973). My very own favourite reference is Iain Banks’ The Participant of Video games (2009), the place an extremely complicated gaming technique have to be tackled by the protagonist inside a wierd empire within the Small Magellanic Cloud. No matter your choice, the Masgellanics proceed to fascinate, and we must always be taught extra from the VLTI because the upgraded GRAVITY+ comes on-line.
The paper is Ohnaka et al., “Imaging the innermost circumstellar setting of the pink supergiant WOH G64 within the Giant Magellanic Cloud,” Astronomy & Astrophysics 14 October 2024 (letter to the editor). Summary.
