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    Herschel’s view of a star nursery
    Herschel’s view of a star nursery

    This image shows Rho Ophiuchi, a vast stellar nursery where new stars take shape from billowing clouds of gas, as viewed by ESA’s Herschel observatory. Located about 440 light-years from us, in the constellation Ophiuchus, the Serpent Bearer, Rho Ophiuchi is one of the nearest star-forming regions to Earth.

    Some of these clouds appear dark when observed at optical and near-infrared wavelengths owing to the presence of dust, a minor but crucial component of the interstellar medium that pervades our Galaxy. However, they appeared anything but dark to the infrared eye of Herschel.

    Observing the sky at far-infrared and submillimetre wavelengths from 2009 to 2013, Herschel could catch the faint glow of dust grains interspersed in these clouds. Astronomers can use this glow to trace the otherwise dark gas where star formation unfolds.

    Herschel’s view reveals a tangled network of filaments, weaving their way from the darker, less dense regions on the left of the image towards the brighter, denser parts of the cloud, on the right. The bright clumps embedded in the cloud are the seeds of future stars and planets.

    Filaments like these were uncovered by Herschel throughout the Galaxy, indicating that these structures play a fundamental role in the processes that lead to the birth of stars.

    This three-colour image combines Herschel observations at 70 microns (blue), 160 microns (green) and 250 microns (red), and spans 7.9° by 4.6°; north is up and east to the left.

    The Herschel Space Observatory was launched on 14 May 2009 and observed the sky for almost four years, until its coolant ran out on 29 April 2013.

    Full story: How Herschel unlocked the secrets of star formation

    Credits: ESA/Herschel/NASA/JPL-Caltech; acknowledgement: R. Hurt (JPL-Caltech), CC BY-SA 3.0 IGO
    Herschel’s view of a molecular cloud
    Herschel’s view of a molecular cloud

    Pictured in this image by ESA’s Herschel observatory is the Orion B molecular cloud, a vast star-forming complex in the constellation Orion, the Hunter. Invisible to our eyes, these interstellar clouds are located near Alnitak, one of the stars in Orion’s Belt.

    At about 1300 light-years from us, Orion B is one of the closest regions of star formation, where new stars take shape from billowing clouds of gas.

    Observing the sky at far-infrared and submillimetre wavelengths from 2009 to 2013, Herschel could catch the faint glow of dust grains interspersed in these clouds. Astronomers can use this glow to trace the otherwise dark gas where star formation unfolds.

    The densest portions of the cloud, where many protostars and newborn stars are found, stand out as the brightest regions in the image.

    The large, bright region in the top right is the Flame Nebula, also known as NGC 2024. This emission nebula is also visible in optical observations owing to light from nearby newborn stars that has energised its gas and made it shine. The nebula was discovered in the late 18th century by William Herschel, the astronomer after whom ESA’s observatory is named.

    The cloud seems to come to an abrupt end to the right of the Flame Nebula, where a sharp edge indicates that the material is being compressed by powerful winds blowing from clusters of massive stars located beyond the field of this image.

    Protruding from this edge, and visible in this image as a small lump, is the iconic Horsehead Nebula. A thick pillar of interstellar material with a shape resembling an equine head, this nebula was first identified by astronomer Williamina Fleming in the 1880s. She spotted this dark nebula in photographic observations that were taken at optical wavelengths, where it appeared as a silhouette because of the obscuring effect of the dust interspersed in the gas.

    Darker regions in the central and lower left parts of the image correspond to colder, less dense portions of the cloud where star formation is not as active. Nestled within the tangle of gas and dust, the two bright regions at the centre of the image are NGC 2071 and NGC 2068, two reflection nebulas, which reflect starlight and also shine brightly at visible wavelengths.
     
    This three-colour image combines Herschel observations at 70 microns (blue), 160 microns (green) and 250 microns (red), and spans 8.6° by 6.2°; north is to the left and east is down.

    The Herschel Space Observatory was launched on 14 May 2009 and observed the sky for almost four years, until its coolant ran out on 29 April 2013.

    Full story: How Herschel unlocked the secrets of star formation

    Credits: ESA/Herschel/NASA/JPL-Caltech; acknowledgement: R. Hurt (JPL-Caltech), CC BY-SA 3.0 IGO
    Herschel’s view of new stars and molecular clouds
    Herschel’s view of new stars and molecular clouds

    The bubbles and wisps portrayed in this image by ESA’s Herschel observatory reveal great turmoil in the W3/W4/W5 complex of molecular clouds and star-forming regions. Located over 6000 light-years away, in the northern constellation Cassiopeia, it is one of the best regions in which to study the life and death of massive stars in our Milky Way galaxy.

    Observing the sky at far-infrared and submillimetre wavelengths from 2009 to 2013, Herschel could catch the faint glow of dust grains interspersed in these clouds. Astronomers can use this glow to trace the otherwise dark gas where star formation unfolds.

    The three regions that make up the complex – W3, W4 and W5 – owe their name to astronomer Gart Westerhout, who identified them in the 1950s as the third, fourth and fifth sources of his survey of the Galaxy at radio wavelengths.

    The bright, white region towards the top right of the image, hosting three brilliant spots, is W3, a giant molecular cloud containing one of the most active factories of massive stars in the outer Milky Way. For its star-making activity, the cloud draws from a total reservoir of raw material equivalent to several hundred thousand times the mass of our Sun.

    The large, blue-greenish cavity to the lower left of W3 is W4, a bubble carved by winds and supernova explosions of the massive stars in IC1805, the star-forming region at its core.

    The other large cavity, on the left side of the image, is W5, consisting of two adjacent bubbles powered by intense winds and explosions of the massive stars that are coming to life in several stellar nurseries nestled within this region.

    Many seeds of new stars in this complex, especially in W3 and W5, have been observed along pillars, edges and other features that are being sculpted in the cloud material by the mighty effects of nearby massive stars. This suggests that each generation of stars is triggering the formation of the next one.

    While these regions are prime locations to study the poorly understood processes that lead to the formation of massive stars, they also host large amounts of young, low-mass stars, providing astronomers with an extraordinary laboratory to investigate the full complexity of star formation in the Milky Way.

    This two-colour image combines Herschel observations at 70 microns (cyan) and 100 microns (orange), and spans about 8.4° by 2.9°; north is up and east to the left.

    The Herschel Space Observatory was launched on 14 May 2009 and observed the sky for almost four years, until its coolant ran out on 29 April 2013.

    Full story: How Herschel unlocked the secrets of star formation

    Credits: ESA/Herschel/NASA/JPL-Caltech; acknowledgement: R. Hurt (JPL-Caltech), CC BY-SA 3.0 IGO
    Herschel’s view of the Taurus molecular cloud
    Herschel’s view of the Taurus molecular cloud

    This mosaic combines several observations of the Taurus Molecular Cloud performed by ESA’s Herschel observatory. Located about 450 light-years from us, in the constellation Taurus, the Bull, this vast complex of interstellar clouds is where a myriad of stars are being born, and is the closest large region of star formation.

    Observing the sky at far-infrared and submillimetre wavelengths from 2009 to 2013, Herschel could catch the faint glow of dust grains dispersed through these clouds. Astronomers can use this glow to trace the otherwise dark gas where star formation unfolds.

    The darker, blue-hued areas throughout the image correspond to colder, less dense portions of the cloud, while the brighter, red-hued regions are the densest environments, where the star-forming activity is most intense.

    The densest regions are distributed along an intricate network of filaments, teeming with bright clumps: the seeds of future stars. This is a textbook example of the filamentary structures that were spotted by Herschel nearly everywhere in the Galaxy, demonstrating the key role of filaments in star formation.

    Embedded in the bright clump towards the top left of the image is Lynds 1544, a pre-stellar core that will later turn into a star. Here, Herschel detected water vapour – the first time this molecule was ever found in a prestellar core – in an amount that exceeds, by over 2000 times, the water content of Earth’s oceans.

    Herschel observations of the tangled structures in the top right of the image have shown that the material along filaments is not at all static. In fact, the most prominent filaments appear to be drawing matter from their surroundings through a network of lower-density filaments, known as striations, perpendicular to the main filament. In these regions, astronomers found that magnetic fields tend to be perpendicular to the densest, star-forming filaments and parallel to the striations, indicating that they must also play an important role in the processes that lead to stellar birth.

    This four-colour image combines Herschel observations at 160 microns (blue), 250 microns (green), 350 microns (split between green and red) and 500 microns (red), and spans 13.8° by 7.3°; north is up and east to the left.

    The Herschel Space Observatory was launched on 14 May 2009 and observed the sky for almost four years, until its coolant ran out on 29 April 2013.

    Full story: The cosmic water trail uncovered by Herschel

    Credits: ESA/Herschel/NASA/JPL-Caltech; acknowledgement: R. Hurt (JPL-Caltech), CC BY-SA 3.0 IGO
    Herschel’s view of the Pinwheel Galaxy
    Herschel’s view of the Pinwheel Galaxy

    This image shows the Pinwheel Galaxy, also known as M101, as viewed by ESA’s Herschel observatory. Lying more than 20 million light-years from us, this spiral galaxy is similar in shape to our Milky Way, but it is almost twice as large.

    Herschel's observations at far-infrared and submillimetre wavelengths reveal the glow of cosmic dust, which is a minor but crucial ingredient in the interstellar material in the galaxy’s spiral arms. This mixture of gas and dust provides the raw material to produce the galaxy’s future generations of stars.

    The Pinwheel Galaxy is in the constellation Ursa Major, the Big Dipper. Thanks to its orientation, we can enjoy a face-on view of the beautiful spiral structure of the galaxy’s disc.

    The spiral arms are dotted with several bright, blue-hued spots of light: these are regions where large numbers of massive stars are being born.

    This three-colour image combines Herschel observations at 70 and 100 microns (blue), 160 and 250 microns (green), and 350 and 500 microns (red). North is up and east to the left.

    The Herschel Space Observatory was launched on 14 May 2009 and observed the sky for almost four years, until its coolant ran out on 29 April 2013.

    Full story: Herschel’s chronicles of galaxy evolution

    Credits: ESA/Herschel/NASA/JPL-Caltech; acknowledgement: R. Hurt (JPL-Caltech), CC BY-SA 3.0 IGO
    Herschel’s view of NGC 1097
    Herschel’s view of NGC 1097

    Portrayed in this image by ESA’s Herschel observatory is NGC 1097, a barred spiral galaxy located some 50 million light-years from us, in the southern constellation Fornax, the Furnace.

    The blue regions sprinkled across the galaxy’s two spiral arms are sites of intense star formation. There, the energy from newborn stars has heated up the dust interspersed in the interstellar gas, making it glow at the far-infrared and submillimetre wavelengths probed by Herschel.

    The dwarf elliptical galaxy NGC 1097A, a small satellite of NGC 1097, can be seen as the fuzzy blue blob in the top right, halfway between the two spiral arms.

    The bright core of the NGC 1097, surrounded by a glowing ring where most of the galaxy’s prodigious star formation is taking place, conceals a supermassive black hole about a hundred million times the mass of our Sun. This black hole is devouring matter from its vicinity, causing the galactic core to shine brightly across the electromagnetic spectrum, from X-rays to radio waves.

    This galaxy was discovered – and originally identified as a nebula – in the late 18th century in optical observations by William Herschel, the astronomer after whom the observatory is named. Despite the source’s location in the southern sky, it was still visible a few degrees above the horizon at the site in England where Herschel made his observations.

    This three-colour image combines Herschel observations at 70 and 100 microns (blue), 160 and 250 microns (green), and 350 and 500 microns (red). North is up and east to the left.

    The Herschel Space Observatory was launched on 14 May 2009 and observed the sky for almost four years, until its coolant ran out on 29 April 2013.

    Full story: Herschel’s chronicles of galaxy evolution

    Credits: ESA/Herschel/NASA/JPL-Caltech; acknowledgement: R. Hurt (JPL-Caltech), CC BY-SA 3.0 IGO

    From stars to galaxies

    Explore stellar nurseries in our Milky Way and other galaxies as viewed through the infrared eye of the Herschel space observatory