An image at radio wavelengths of a young stellar quadruplet. Astronomers have discovered four distinct gas condensations in a clumpy, filamentary gas cloud (white) surrounded by dust (blue). The locations of the condensations in this image are marked with black and red dots. The four condensations are destined to form a bound multiple star system, and one of them (the red dot) has already turned on as a protostar.
On April 29, the European Space Agency announced that its premier infrared space observatory had run out of coolant and the mission had come to an end. Observing the cosmos in far-infrared wavelengths, the space telescope has given us some of the most striking views of cool nebulae, star forming regions, comets being pulverized around nearby stars, even asteroids buzzing around our own solar system. As we say goodbye to the historic mission, and astronomers continue to analyze the huge wealth of data Herschel has left us with, it's time to have a look back at some of the mission's most spectacular observations.
In this picture, embryonic stars feed on the gas and dust clouds deep inside the Orion Nebula. This image combines far-infrared data by Herschel and mid-infrared data by NASA's Spitzer space telescope.
ESA/Herschel/PACS & SPIRE Consortium, O. Krause, HSC, H. Linz
The Andromeda galaxy in infrared -- Herschel took this portrait of the famous spiral galaxy, picking out the fine detail from gas and dust running through its structure.
ESA/PACS & SPIRE consortia, A. Rivera-Ingraham & P.G. Martin, Univ. Toronto, HOBYS Key Programme (F. Motte)
This three-color image of the W3 giant molecular cloud combines Herschel's 70 μm (blue), 160 μm (green) and 250 μm (red) filters. W3 is located about 6200 light-years away and is a hub of intense star formation. Filaments of gas and dust cocooning protostars (yellow dots) can be seen.
ESA/Herschel/PACS/L. Decin et al
The star Betelgeuse is observed in infrared by Herschel as it rapidly approaches a "barrier" of interstellar gas. The bow shock of the star's stellar winds can easily be seen.
ESA/Bonsor et al (2013)
The star Kappa Coronae Borealis is captured in this infrared observation by Herschel. The star itself is blocked out whereas the ring of debris (likely from asteroid/comet impacts) glows bright.
ESA/Herschel/PACS/Bram Acke, KU Leuven, Belgium
The infrared emissions from dust produced by a huge number of cometary collisions surrounding the famous star Fomalhaut glows in bright blue in Herschel's eye. At least one exoplanet is known to orbit within this ring of dust.
Herschel: Q. Nguyen Luong & F. Motte, HOBYS Key Program consortium, Herschel SPIRE/PACS/ESA consortia. XMM-Newton: ESA/XMM-Newton
Supernova remnant W44 is the focus of this observation created by combining data from ESA's Herschel and XMM-Newton space observatories.
ESA and SPIRE & PACS consortia, Ph. André (CEA Saclay) for Gould’s Belt Key Programme Consortia
Herschel picks out 600 newly forming stars inside the W40 nebula cradle of stars -- located 1,000 light-years away in the constellation Aquila.
ESA/Herschel/PACS/MACH-11/MPE/B.Altieri (ESAC) and C. Kiss (Konkoly Observatory)
Herschel could also study solar system objects with ease. In this observation, asteroid Apophis was captured during its approach to Earth on 5/6 January 2013. This image shows the asteroid in Herschel’s three PACS wavelengths: 70, 100 and 160 microns, respectively.
ESA/Herschel/PACS, SPIRE/N. Schneider, Ph. André, V. Könyves (CEA Saclay, France) for the “Gould Belt survey” Key Programme
This striking image complemented Hubble's 23rd anniversary optical view of the Horsehead Nebula. Herschel's infrared observation of the Orion Molecular Cloud complex (including the Horsehead Nebula -- visible far right of image) provided a unique perspective on this astronomical favorite.
New observations of a star-forming nebula have revealed four stellar embryos, providing clues as to how multiple star systems evolve.
The majority of stars in our galaxy come in pairs, triplets or even quadruplets, but our sun appears to be a loner. This fact poses an interesting question: if our star is alone, and yet contains a rich multiplanetary system, how do planetary systems evolve in multi-star systems?
In a new study published in the journal Nature this week, Alyssa Goodman, professor of astronomy at the Harvard-Smithsonian Center for Astrophysics (CfA), reports on the discovery of four embryonic stars slowly forming 825 light-years from Earth. Previously known to contain one protostar, the molecular cloud located in the constellation Perseus apparently contains more stellar siblings.
One of the biggest puzzles in understanding the evolution of multi-star systems is how they formed; did they spawn from the same stellar nursery as true fraternal twins would or did the stars come from different locations only to be gravitationally captured later in their lives? According to theoretical models both ideas are viable.
By studying the radio emissions from the molecular cloud, Goodman’s team discovered “several filamentary gas structures in which they detected three other concentrations,” writes a Smithsonian Astrophysical Observatory news release.
The researchers believe that these gas concentrations, which are two-to-three times more massive than the known protostar, are collapsing under mutual gravity. In other words, stellar quadruplets are coalescing and three of these newly-detected star embryos will likely undergo nuclear fusion in their cores, becoming baby stars, in roughly 40,000 years time. In cosmic timescales, this particular stellar womb is teetering on the edge of giving birth.
Most interesting is the scale of the region. The system measures only 10,000 astronomical units (AU) across — where 1 AU is the average distance between the Earth and sun. For scale, all four stellar embryos would fit easily within the boundaries of our solar system, where the outermost boundary is the Oort Cloud, a hypothetical region containing billions of cometary nuclei surrounding our sun. The inner Oort Cloud’s outermost boundary is 20,000 AU from the sun.
Their close proximity means that all four stars are gravitationally interacting and velocity measurements confirms this possibility.
As pointed out by Goodman, it’s highly probable that as the system evolves, one or more stars may become gravitationally unstable and be flung from the main group. But watching stellar quadruplets spark to life in a gravitationally-bound arrangement will help astronomers refine stellar models in multi-star systems and perhaps begin to understand how their gravitational interactions will influence planetary formation.
Multi-star systems feature heavily in science fiction and in the 2003 “Battlestar Galactica” re-imagined TV series (and the spin-off 2009 “Caprica” series), human civilization spawns from the Twelve Colonies of Kobol, two binary star systems in orbit around one another, each star possessing its own systems of planets, 12 in total.
Could this new discovery be the genesis of a Colonies-like star system, each star hosting its own system of planets? Well, it’s too early to tell, but astrophysicists will be trying to work out whether multi-star systems like these are gravitationally stable enough to nurture the evolution of planetary systems, potentially following where science fiction has already explored.
Source: Harvard-Smithsonian Center for Astrophysics (CfA)