Water-Building Molecule in the Ring Nebula

The Ring Nebula at optical wavelengths as seen by the Hubble Space Telescope, with Herschel data acquired with SPIRE and PACS over a wavelength range of 51–672 micrometers for the region identified. The spectra have been cropped and the scales stretched in order to show the OH+ emission, a molecular ion important for the formation of water. ESA’s Herschel space observatory is the first to detect this molecule in planetary nebulas – the product of dying Sun-like stars.

For more information, see New Molecules Around Old Stars.

Image credit: Hubble image: NASA/ESA/C. Robert O’Dell (Vanderbilt University) Herschel data: ESA/Herschel/PACS & SPIRE/ HerPlaNS survey/I. Aleman et al.

Herschel's 37,000 Science Observations

This animation shows the timeline of over 37,000 scientific observations made by ESA’s Herschel space observatory throughout its entire mission, condensed into less than a minute.

The animation was prepared by Pedro Gómez-Alvarez in the Herschel Science Centre and presented by Herschel’s Project Scientist Göran Pilbratt during the opening session of The Universe Explored by Herschel symposium held at ESA’s ESTEC facility, in Noordwijk, the Netherlands, last month.

The animation runs from launch, on 14 May 2009, until the infrared observatory made its last observation on 29 April 2013.

Running through the center of the graphic is the ‘ecliptic plane’ tracing the paths of the planets with respect to Herschel’s viewpoint from its orbit around L2, which is located 1.5 million kilometers behind the Earth as viewed from the Sun.

A horseshoe shape marks the Galactic Plane, the direction in which much of the Milky Way’s mass lies, and where many of Herschel’s observations were focused.

In total, Herschel observed almost a tenth of the entire sky for over 23,500 hours, providing new views into the previously hidden Universe, pointing to unseen star birth and galaxy formation, and tracing water through the Universe from molecular clouds to newborn stars and to their planet-forming discs and belts of comets.

Its two camera/imaging spectrometers, PACS (Photoconductor Array Camera and Spectrometer) and SPIRE (Spectral and Photometric Imaging Receiver), which together covered wavelengths of 55–670 microns, provided about two thirds of Herschel’s sky coverage in parallel imaging mode. These data points are shown in yellow.

PACS and SPIRE photometry observations are indicated in blue and green, which together with spectroscopy performed with PACS, SPIRE and the third science instrument, HIFI (Heterodyne Instrument for the Far Infrared, covering wavelength bands of 157–212 microns and 240–625 microns) make up the remainder.

Since 29 October 2013, when the last observed data went public, all of the Herschel data are available to the worldwide astronomical community. The vast data archive will become the scientific legacy of the mission, destined to yield far more discoveries than have been made over the mission lifetime so far.

Video credit: ESA & P. Gómez-Alvarez / music: B. Lynne.

Snow Rings Around TW Hydrae

An artist's concept of the snow line in TW Hydrae showing water ice covered dust grains in the inner disc (4.5–30 astronomical units, blue) and carbon monoxide ice covered grains in the outer disc (>30 astronomical units, green). The transition from blue to green marks the carbon monoxide snow line. The snow helps grains of dust to adhere to each other by providing a sticky coating, which is essential to the formation of planets and comets. Due to the different freezing points of different chemical compounds, different snow lines can be found at various distances from the star.

This ALMA image shows the region where carbon monoxide snow has formed around the star. The carbon monoxide is shown here in green, and begins at a distance of more than 30 astronomical units from TW Hydrae. Aside from being necessary for planetary and comet formation, carbon monoxide is needed for the creation of methanol which is a fundamental building block required for life.

Credit: (top) B. Saxton & A. Angelich/NRAO/AUI/NSF/ALMA (ESO/NAOJ/NRAO); (bottom) ALMA (ESO/NAOJ/NRAO)

Note: For more information, see Snow in an Infant Planetary System.

Misty Star in the Sea Serpent

This artist's concept illustrates an icy planet-forming disk around a young star called TW Hydrae, located about 175 light-years away in the Hydra, or Sea Serpent, constellation. Astronomers using the Herschel Space Observatory detected copious amounts of cool water vapor, illustrated in blue, emanating from the star's planet-forming disk of dust and gas. The water vapor, which probably comes from icy grains in the disk, is located in the frigid outer regions of the star system, where comets will take shape.

In our own solar system, comets are thought to have carried water to Earth, creating our oceans. A similar process might be taking place around TW Hydrae -- comets could, over the next several millions of years, transport water to young worlds. The Herschel results demonstrate that vast reservoirs of water are available around stars for creating these hypothetical water worlds.

The graph of data (Figure 1) from Herschel shows how the cool water vapor was detected. Water molecules come in two "spin" forms, called ortho and para, in which the two spins of the hydrogen nuclei have different orientations. In this case, the team compared the ratio of ortho to para water seen in the TW Hydrae disk to that in comets, and found very low values. Lower ratios indicate cooler temperatures, though in practice the analysis is much more complicated. This is the first demonstration that water exists in large quantities in the frigid, outer regions of solar systems, where comets take shape.

Illustration credit: ESA/NASA/JPL-Caltech/Leiden Observatory

Note: For more information, see Herschel Discovers Tip of Cosmic Iceberg Around Nearby Young Star.

Heavy Bombardment at Eta Corvi

This artist's conception illustrates a storm of comets around a star near our own, called Eta Corvi. Evidence for this barrage comes from NASA's Spitzer Space Telescope, whose infrared detectors picked up indications that one or more comets was recently torn to shreds after colliding with a rocky body. In this artist's conception, one such giant comet is shown smashing into a rocky planet, flinging ice- and carbon-rich dust into space, while also smashing water and organics into the surface of the planet. A glowing red flash captures the moment of impact on the planet. Yellow-white Eta Corvi is shown to the left, with still more comets streaming toward it.

Spitzer detected spectral signatures of water ice, organics and rock around Eta Corvi -- key ingredients of comets. This is the first time that evidence for such a comet storm has been seen around another star. Eta Corvi is just about the right age, about one billion years old, to be experiencing a bombardment of comets akin to what occurred in our own solar system at 600 to 800 millions years of age, termed the Late Heavy Bombardment.

Scientists say the Late Heavy Bombardment was triggered in our solar system by the migration of our outer planets, which jostled icy comets about, sending some of them flying inward. The incoming comets scarred our moon and pummeled our inner planets. They may have even brought materials to Earth that helped kick start life.

Illustration Credit: NASA/JPL-Caltech

Note: For more information, see Comet Storm in a Nearby Star System .

Spectrum Analysis of Organic Molecules in the Orion Nebula

The HIFI spectrum of the Orion Nebula, superimposed on a Spitzer image of Orion. A characteristic feature is the spectral richness: among the organic molecules identified in this spectrum are water, carbon monoxide, formaldehyde, methanol, dimethyl ether, hydrogen cyanide, sulphur oxide, sulphur dioxide and their isotope analogues. It is expected that new molecules will also be identified. This spectrum is the first glimpse at the spectral richness of regions of star and planet formation. It harbors the promise of a deep understanding of the chemistry of space once the complete spectral surveys are available.

Image credit: ESA, HEXOS and the HIFI consortium

Notes: HIFI stands for Heterodyne Instrument for the Far Infrared, an instrument on board the Herschel Space Observatory. For more information, see Herschel-HIFI Unveils Precursors of Life-Enabling Molecules in Orion Nebula.