Fomalhaut

Surprise! Fomalhaut’s kid sister has a debris disk too

The bright star Fomalhaut hosts a spectacular debris disk: a dusty circling plane of small objects where planets form. At a mere 25 light-years away, we’ve been able to pinpoint detailed features: from the warm disk close by to the further disk that is comparable to the Solar System’s Kuiper belt.

But Fomalhaut never ceases to surprise us. At first we discovered a planet, Fomalhaut b, which orbits in the clearing between the two disks. Then we discovered that Fomalhaut was not a single star or a double star, but a triplet.  The breaking news today, however, is that we have discovered a mini debris disk around the third star.

Fomalhaut is massive, weighing in at 1.9 times the mass of the Sun. And at such a close distance it’s one of the brightest stars in the southern sky. But its two companions are much smaller. The second star, Fomalhaut B, is 0.7 times the mass of the Sun and the third star, Fomalhaut C, a small red dwarf, is 0.2 times the mass of the Sun.

Fomalhaut C orbits Fomalhaut A at a distance of 2.5 light-years, or roughly half the distance from the Sun to the closest neighboring star.  It was only confirmed to be gravitationally bound to Fomalhaut A and Fomalhaut B in October of last year.

“The disk around Fomalhaut C was a complete surprise,” lead researcher Grant Kennedy of the University of Cambridge told Universe Today. “This is only the second system in which disks around two separate stars have been discovered.”

Relatively cool dust and ice particles are much brighter at long wavelengths, allowing telescopes like the Herschel Space Telescope, to pick up the excess infrared light. However, Herschel has a much poorer resolution than an optical telescope so the image of Fomalhaut C’s disk is not spatially resolved — meaning the brightness of the disk could be measured but not its structure.

Kennedy’s team’s best guess is that the disk is quite cold, around 24 degrees Kelvin and pretty small, orbiting to and extent of 10 times the distance from the Earth to the Sun. But it’s likely that it’s similar to Fomalhaut A’s disk in that it’s bright, elliptical, and slightly offset from its host star. All three characteristics suggest that gravitational perturbations may be destabilizing the cometary orbits within the disks.

Image credit: Amanda Smith

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Fomalhaut: Actually Triple Star, Astronomers Say

In a new study accepted for publication in the Astronomical Journal (arXiv.org), astronomers show that a previously known red dwarf star called LP 876-10 is part of the Fomalhaut system.

Fomalhaut, the 18th brightest star visible in night sky, is located in the constellation Piscis Austrinus about 25 light-years from Earth. The star is twice as massive as the Sun and 20 times brighter.

The name Fomalhaut derives from the Arabic name for this star – Fum al Hut, meaning ‘the Fish’s Mouth.’

Fomalhaut has been featured in science fiction novels by writers Isaac Asimov, Stanislaw Lem, Philip K. Dick, and Frank Herbert.

Despite being a well-studied system, it was only recently confirmed that Fomalhaut was a binary star – two stars (Fomalhaut A and B) that orbit each other – although it had been first suggested in the 1890s.

In the new study, lead author Dr Eric Mamajek of the University of Rochester and his colleagues have found the triple nature of Fomalhaut through a bit of detective work.

“I noticed this third star a couple of years ago when I was plotting the motions of stars in the vicinity of Fomalhaut for another study,” Dr Mamajek said.

“However I needed to collect more data and gather a team of co-authors with different observations to test whether the star’s properties are consistent with being a third member of the Fomalhaut system.”

By carefully analyzing astrometric and spectroscopic measurements, the astronomers were able to measure the distance and speed of the third star. They concluded that a star known as LP 876-10 is part of the Fomalhaut system, making it Fomalhaut C.

Full Article

Image Credit: Eric E. Mamajek et al/David Hardy

Double star Fomalhaut may actually be a triplet

Fomalhaut is a really cool place to study. The naked-eye star (the brightest star in the constellation Piscis Austrinus) has a planet, Fomalhaut b, that once appeared dead but rose again in science circles. It is the site of a comet massacre. Now it’s getting even more interesting: Scientists have believed for years that Fomalhaut is a double star, but a new paper proposes that it is actually a triplet.

“I noticed this third star a couple of years ago when I was plotting the motions of stars in the vicinity of Fomalhaut for another study,” stated Eric Mamajek, associate professor of physics and astronomy at the University of Rochester. The third star is known as LP876-10 or Fomalhaut C.

“However, I needed to collect more data and gather a team of co-authors with different observations to test whether the star’s properties are consistent with being a third member of the Fomalhaut system.”

That opportunity came when Mamajek was in Chile and by chance, talking with Georgia State University’s Todd Henry, who is the director of the Research Consortium on Nearby Stars. A student (who has now graduated), Jennifer Bartlett at the University of Virginia, was working on a study of potential nearby stars for her Ph.D. thesis, which included the star that Mamajek was curious about.

The team plotted the star’s movements and spectroscopy (to see its temperature and radial velocity) and concluded the speed and distance of the star matched that of the Fomalhaut system.

LP876-10/Fomalhaut C is a red dwarf that appears the distance of 11 full moons apart from Fomalhaut in the night sky. It seems counter intuitive to believe they are close together, but the team reminds us that Fomalhaut is very close to us as stars go: 25 light-years away.

Image credit: NASA, ESA, and P. Kalas (University of California, Berkeley and SETI Institute)

Companion’s comets the key to curious exoplanet system

The nearby star Fomalhaut A hosts the most famous planetary system outside our own Solar System, containing both an exoplanet and a spectacular ring of comets. Today, an international team of astronomers announced a new discovery with the Herschel Space Observatory that has made this system even more intriguing; the least massive star of the three in the Fomalhaut system, Fomalhaut C, has now been found to host its own comet belt. 

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Dust rings not ‘smoking gun’ for planets after all

There can be smoke without fire. Sharp rings of dust around stars aren’t always carved by planets but can form on their own – bad news for those who use the structures to guide them to stars that host planets. The finding also has implications for the existence of a controversial candidate exoplanet.

The discs of dust and gas debris surrounding stars sometimes produce sharply defined or elongated rings. These were assumed to be the calling cards of unseen planets, carved by the bodies as they travel through the disc.

“I call it the dark matter argument,” says Wladimir Lyra at NASA’s Jet Propulsion Laboratory in Pasadena, California. “There is something you are seeing that you cannot explain, and you blame the gravity of something you cannot see.”

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At the center of this image is the star called Fomalhaut. Some researchers believe that this star is the “eye of Odin” described as being in Mimir’s spring. It’s interesting that this 2008 image form Hubble is in the shape of an eye.

So Long, Fomalhaut

once on that blurry
breaths, you saw
through me; with
clandestine sorrows
that I kept for
myriads of yesterdays–
still, watching me;
you saw through these
fickle, thick clouds
that had enveloped
me for the
outstretched hands of
time–still, raining
infinitely.
once, you saw through
it all and took
edge upon the blemishes
I didn’t mean to
disport. but
hardly any moons
could swim
the ocean of
light years in me
still
you did fell
into the trap
of my hollowness;
hence, here I am
helping you
out before we
two get drowned
into
the constellation of love;
into the empty space 
of reverse.

ALMA observes a ring around the bright star Fomalhaut by European Southern Observatory on Flickr.

Via Flickr:
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.

More information: www.eso.org/public/images/eso1216a/


Credit:

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

Acknowledgement: 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)

This wide-field view shows the sky around the bright star Fomalhaut in the constellation of Piscis Austrinus (The Southern Fish). This picture was created from photographs forming part of the Digitized Sky Survey 2. Fomalhaut lies about 25 light-years from the Earth and is surrounded by a huge disc of dust.

credit: NASA, ESA, and the Digitized Sky Survey 2. Acknowledgment: Davide De Martin (ESA/Hubble)