Dark Nebula Dobashi 4173 and Reflection Nebula [B77] 63

This new NASA/ESA Hubble Space Telescope image shows a variety of intriguing cosmic phenomena.

Surrounded by bright stars, towards the upper middle of the frame we see a small young stellar object (YSO) known as SSTC2D J033038.2+303212. Located in the constellation of Perseus, this star is in the early stages of its life and is still forming into a fully grown star. In this view from Hubble’s Advanced Camera for Surveys (ACS) it appears to have a murky chimney of material emanating outwards and downwards, framed by bright bursts of gas flowing from the star itself. This fledgling star is actually surrounded by a bright disc of material swirling around it as it forms — a disc that we see edge-on from our perspective.

However, this small bright speck is dwarfed by its cosmic neighbor towards the bottom of the frame, a clump of bright, wispy gas swirling around as it appears to spew dark material out into space. The bright cloud is a reflection nebula known as [B77] 63, a cloud of interstellar gas that is reflecting light from the stars embedded within it. There are actually a number of bright stars within [B77] 63, most notably the emission-line star LkHA 326, and its very near neighbor LZK 18.

These stars are lighting up the surrounding gas and sculpting it into the wispy shape seen in this image. However, the most dramatic part of the image seems to be a dark stream of smoke piling outwards from [B77] 63 and its stars — a dark nebula called Dobashi 4173. Dark nebulae are incredibly dense clouds of pitch-dark material that obscure the patches of sky behind them, seemingly creating great rips and eerily empty chunks of sky. The stars speckled on top of this extreme blackness actually lie between us and Dobashi 4173.

Image credit: ESA

"Blinking" Binary Star System YLW 16A

In this artist's impression, a disk of dusty material leftover from star formation girds two young stars like a hula hoop. As the two stars whirl around each other, they periodically peek out from the disk, making the system appear to "blink" every 93 days.

The dusty hula hoop itself is misaligned from the central star pair, thanks to the disrupting gravitational presence of a third star orbiting at the periphery of the system. The light yellow arcs near the two central stars indicate their movement relative to each other and the disk. It is believed that this disk will go on to spawn planets and the other celestial bodies that make up a solar system.

NASA's Spitzer Space Telescope observed this system, called YLW 16A, in the infrared light emitted by the disk's warmed gas and dust.

Illustration credit: NASA/JPL-Caltech

Note: For more information, see Spitzer Discovers Young Stars with a 'Hula Hoop.'

PV Cephei and Gyulbudaghian's Nebula

The Universe is rarely static, although the timescales involved can be very long. Since modern astronomical observations began we have been observing the birthplaces of new stars and planets, searching for and studying the subtle changes that help us to figure out what is happening within.

The bright spot located at the edge of the bluish fan-shaped structure in this Hubble image is a young star called V* PV Cephei, or PV Cep. It is a favorite target for amateur astronomers because the fan-shaped nebulosity, known as GM 1-29 or Gyulbudaghian’s Nebula, changes over a timescale of months. The brightness of the star has also varied over time.

Images of PV Cep taken in 1952 showed a nebulous streak, similar to a comet’s tail. However, these had vanished when new images of the star were obtained some twenty-five years later. Instead, the blue fan-shaped nebula had appeared. Twenty-five years is a very short period on cosmic timescales, so astronomers think that the mysterious streak may have been a temporary phenomenon, such as the remnants of a massive stellar flare — similar to the solar flares we are used to seeing in the Solar System.

At the same time as this was happening, the star itself was brightening. This provided the light to illuminate the newly formed fan-shaped nebula. This brightening might be related to the start of the hydrogen-burning phase of the star, which would mean that it was reaching maturity.

PV Cep is thought to be surrounded by a disc of gas and dust, which would stop light from escaping in all directions. The fan-like appearance is therefore probably a result of starlight escaping from the dust disc and projecting onto the nebula.

PV Cep is located in the northern constellation of Cepheus at a distance of over 1600 light-years from Earth.

Photo credit: ESA/Hubble & NASA. Acknowledgement: Alexey Romashin

HH 151

This image shows an object known as HH 151, a bright jet of glowing material trailed by an intricate, orange-hued plume of gas and dust. It is located some 460 light-years away in the constellation of Taurus (The Bull), near to the young, tumultuous star HL Tau.

In the first few hundred thousand years of life, new stars like HL Tau pull in material that falls towards them from the surrounding space. This material forms a hot disc that swirls around the coalescing body, launching narrow streams of material from its poles. These jets are shot out at speeds of several hundred kilometers per second and collide violently with nearby clumps of dust and gas, creating wispy, billowing structures known as Herbig-Haro objects — like HH 151 seen in the image above.

Such objects are very common in star-forming regions. They are short-lived, and their motion and evolution can actually be seen over very short timescales, on the order of years. They quickly race away from the newly-forming star that emitted them, colliding with new clumps of material and glowing brightly before fading away.

Image credit: ESA/Hubble & NASA. Acknowledgement: Gilles Chapdelaine

Fomalhaut's Ring by ALMA

This view shows a new picture of the dust ring around the bright star Fomalhaut from the Atacama Large Millimeter/submillimeter Array (ALMA). The underlying blue picture shows an earlier picture obtained by the NASA/ESA Hubble Space Telescope. The new ALMA image has given astronomers a major breakthrough in understanding a nearby planetary system and provided valuable clues about how such systems form and evolve. Note that ALMA has so far only observed a part of the ring.

Photo credit: ALMA (ESO/NAOJ/NRAO). Visible light image: the NASA/ESA Hubble Space Telescope

Acknowledgment: A.C. Boley (University of Florida, Sagan Fellow), M.J. Payne, E.B. Ford, M. Shabran (University of Florida), S. Corder (North American ALMA Science Center, National Radio Astronomy Observatory), and W. Dent (ALMA, Chile), P. Kalas, J. Graham, E. Chiang, E. Kite (University of California, Berkeley), M. Clampin (NASA Goddard Space Flight Center), M. Fitzgerald (Lawrence Livermore National Laboratory), and K. Stapelfeldt and J. Krist (NASA Jet Propulsion Laboratory)

Note: For more information, see ALMA Reveals Workings of Nearby Planetary System.

Fomalhaut and its Debris Disc

This image shows the thermal emission from the young star Fomalhaut and the debris disc surrounding it, as recorded with ESA's Herschel Space Observatory at a wavelength of 70 microns. Together with other data, this image suggests that the dust in Fomalhaut's debris disc consists of 'fluffy' aggregates: large conglomerates of small dust grains with lots of empty space in the structure.

Fluffy dust aggregates are believed to arise from collisions between comets. The radiation pressure exerted by the star, however, is expected to blow out small dust particles very efficiently, expelling grains from the disc immediately after they are produced by comet collisions. In order to explain the observed emission from Fomalhaut's debris disc, astronomers invoke a steady production of dust particles via comet collisions, with an average rate of 2000 daily collisions between comets with a size of one kilometer across or, alternatively, of 2 daily collisions between 10-kilometre-diameter comets.

The total mass of Fomalhaut's debris disc amounts to 110 times the mass of the Earth. This translates into a very large number of comets, ranging between 10^11 and 10^13, depending on their sizes. This is comparable to the mass of the primordial Kuiper Belt, which astronomers estimate to be of the order of 30 Earth masses.

Photo credit: ESA/Herschel/PACS/Bram Acke, KU Leuven, Belgium

Note: For more information, see Herschel Images Extrasolar Analogue of the Kuiper Belt; for a graphic that compares the size of the Fomalhaut planetary system to that of our own solar system, see Comparison of Fomalhaut's Debris Disc with the Solar System. Also, Herschel Spots Comet Massacre Around Nearby Star.

Artist's Impression of the Brown Dwarf 2M1207

This illustration shows an artist's impression of the brown dwarf 2MASSW J1207334-393254, or 2M1207 for short. With a mass that amounts to 25 times that of Jupiter, 2M1207 is surrounded by a circumstellar disc of gas and dust and possesses a planetary companion five times more massive than Jupiter. The planetary companion lies at a very large distance from 2M1207 – the projected distance between the two bodies measuring 55 astronomical units (AU).

Sub-millimeter observations performed with the SPIRE instrument on board ESA's Herschel Space Observatory have shown that the disc's total mass amounts to about three to five times the mass of Jupiter and that its radius ranges between 50 and 100 AU. With such a massive disc, it is likely that the planetary-mass companion originated directly from disc fragmentation, thus challenging the standard scenario of giant planet formation via core accretion.

Illustration credit: ESA

Note: For more information, see Herschel's New View on Giant Planet Formation.

Star Formation in the Orion Nebula

This new view of the Orion Nebula shows embryonic stars within extensive gas and dust clouds. Combining far-infrared observations from the Herschel Space Observatory and mid-infrared observations from NASA's Spitzer Space Telescope, the image shows newly forming stars surrounded by remnant gas and dust in the form of discs and larger envelopes.

Data from the PACS instrument on Herschel at wavelengths of 70 and 160 microns (a micron is a millionth of a meter) are shown as green and red, respectively, and reveal emission from the disks and envelopes of the very youngest protostars. Two Spitzer instruments, IRAC and MIPS, were used to obtain images of the same region at 8 and 24 microns, which are combined here as blue. These wavelengths show emission from the hotter regions of discs around somewhat older stars.

The region shown covers roughly 25x25 arcminutes on the sky or 3x3 parsecs at the distance to Orion.

Photo credits: ESA/PACS/NASA/JPL-Caltech/IRAM

Note: For more information, see Fledgling Stars Flicker in the Heart of Orion; also, Young Stars Flicker Amidst Clouds of Gas and Dust.