Hello Space Fans and welcome to another edition of Space Fan News.
Astronomers using ESO’s Very Large Telescope and the Canada-France-Hawaii Telescope have
identified a body that is very probably a planet wandering through space without a parent
star.
This is the most exciting free-floating planet candidate found so far and the closest such
object to the Solar System.
It's about 100 light-years away and its relatively close proximity, and the absence of any bright
star very close to it, has allowed the team to study its atmosphere in great detail.
This object also gives astronomers a preview of the exoplanets that future instruments
aim to image around stars other than the Sun.
Free-floating planets (some people also call them rogue planets) are planetary-mass objects
that roam through space without any ties to a star.
Possible examples of such objects have been found before, and started to become known
in the 1990s, when astronomers found that the point at which a brown dwarf crosses over
into the planetary mass range is difficult to determine.
More recent studies have suggested that there may be huge numbers of these rogue planets
in our galaxy, numbering almost twice as many as there are main sequence stars.
Even though we're found these before but without knowing their ages, it was not possible for
astronomers to know whether they were really planets or brown dwarfs.
Brown dwarfs are “failed” stars that don't have enough mass to trigger the nuclear reactions
that make stars shine.
But now astronomers have discovered an object, called CFBDSIR2149, that seems to be part
of a nearby stream of young stars known as the AB Doradus Moving Group.
I know it sound like a moving company.
The researchers found the object in observations from the Canada-France-Hawaii Telescope and
then harnessed the power of ESO’s Very Large Telescope to examine its properties.
The AB Doradus Moving Group is the closest such group to the Solar System.
Its stars drift through space together and are thought to have formed at the same time.
If the object is associated with this moving group — and hence it is a young object — it
becomes possible to deduce much more about it, including its temperature, mass, and what
its atmosphere is made of.
So if it is associated with the AB Doradus Moving Group (and not there by chance, which
is another possibility) then astronomers estimate the mass of the planet to approximately 4–7
times the mass of Jupiter, with an effective temperature of about 430 degrees Celsius.
The planet’s age would be the same as the moving group itself — 50 to 120 million
years.
So as you can see, the link between the new object and the moving group is the vital clue
that allows astronomers to find the age of the newly discovered object.
the statistical analysis done by the team make it 87% likely that the planet is part
of the group.
This is the first isolated planetary mass object ever identified in a moving group,
and the association with this group makes it the most interesting free-floating planet
candidate identified so far.
Free-floating objects like CFBDSIR2149 are thought to form either as normal planets that
have been booted out of their home systems, or as lone objects like the smallest stars
or brown dwarfs.
In either case these objects are intriguing — either as planets without stars, or as
the tiniest possible objects in a range spanning from the most massive stars to the smallest
brown dwarfs.
According to Philippe Delorme, a member of the discovery team, “These objects are important,
as they can either help us understand more about how planets may be ejected from planetary
systems, or how very light objects can arise from the star formation process.
If this little object is a planet that has been ejected from its native system, it conjures
up the striking image of orphaned worlds, drifting in the emptiness of space.”
These worlds could be common — perhaps as numerous as normal stars.
If CFBDSIR2149 is not associated with the AB Doradus Moving Group it is trickier to
be sure of its nature and properties, and it may instead be characterised as a small
brown dwarf.
Both scenarios represent important questions about how planets and stars form and behave.
Next, astronomers from the Baryon Oscillation Spectroscopic Survey have measured the deceleration
of the early universe before dark energy starting accelerating it.
The universe hasn't always been expanding all the time throughout it's history.
Kind of like a roller coaster, there were times when it was speeding up and slowing
down.
For the past five billion years of so, the universe has been accelerating, but in the
distant past, there have been periods of deceleration.
The new measurement is based on data from the Baryon Oscillation Spectroscopic Survey
(BOSS).
It utilizes a technique pioneered by the Sloan Digital Sky Survey in 2005 called "baryon
acoustic oscillations (BAO)."
The BAO technique uses small variations in matter left over from the early Universe as
a "standard ruler" to compare the size of the Universe at various points in its history.
If we look at the Cosmic Microwave Background, we can see tiny variations from sound waves
that propagated in the early universe, like spreading ripples in a pond, and they imprinted
a characteristic scale on these fluctuations.
In the future, where galaxies appeared and where they did not have evolved from these
fluctuations have evolved into today's walls and voids of galaxies.
If you study them closely, there is a baryon acoustic oscillation scale of about 150 Mpc
which is visible among galaxies today.
BOSS was able to measure the expansion rate of the distant Universe by using quasars to
probe the distribution of hydrogen along the line of sight from the each quasar (red dots
in the upper left) to the Sloan Foundation 2.5-m Telescope on Earth (abstractly represented
as the plane in the lower right).
Light rays from distant quasars (dots at left) are partially absorbed as they pass through
clouds of intergalactic hydrogen gas (center).
When the light arrives at the spectrograph of the Sloan Foundation 2.5-Meter Telescope
(square at right), some has been absorbed, leaving behind a record in the form of a "forest"
of small absorption lines in the observed spectrum.
These lines can be interpreted to make a map of the gas along the line of sight between
us and the quasar.
By examining light from thousands of quasars all over the sky, astronomers can make a detailed
three-dimensional map of the distant universe.
In this illustration, the dots at the far left are quasars, and the thin lines show
light rays that left those quasars more than 10 billion years ago.
Yellow dots are quasars that had been measured by prior projects of the Sloan Digital Sky
Survey.
By measuring the spectra from ten times as many quasars in this range (red dots), BOSS
can reveal the large-scale structure of the early universe in much greater detail.
So these are direct observations of the expansion rate of the universe and the ones from BOSS
represent the farthest one done to date.
Finally, astronomers using the Hubble and Spitzer Space Telescopes have discovered the
farthest galaxy we've seen yet.
Remember back in SFN 78, I told you about the THEN most distant galaxy found in the
MACS J1149 cluster?
It had a measured redshift of z=9.6, putting this galaxy in an epoch of about 800 million
years after the Big Bang.
They had found that galaxy by using the MACS cluster as a lens, which essentially gave
the Hubble another lens through which to magnify and resolve the galaxy, something it couldn't
do without that cluster.
Well, astronomers using both Hubble and Spitzer have broken that record and found a galaxy
observed from only 420 million years after the Big Bang.
Coming in with a redshift of a whopping z=11, the light from this galaxy has been travelling
13.3 billion years to get to us.
This discovery comes to us by way of the CLASH survey, the Cluster Lensing and Supernova
Survey with Hubble and they been using galaxy clusters as lenses for a long time now.
They could never have seen this galaxy without the cluster known as MACS0647-JD, which lies
between us and the distant galaxy at about 4 billion or so light years from Earth.
The gravity from the cluster bent the light from the galaxy, magnifying it just enough
that Hubble could see it.
And what a weird little galaxy it is too.
it is so small it may be in the first embryonic steps of forming an entire galaxy.
An analysis shows that the galaxy is less than 600 light-years wide.
Based on observations of somewhat closer galaxies, astronomers estimate that a typical galaxy
of that epoch should be about 2,000 light-years wide.
Now, I'm going to stop there because this Monday, we will be holding our third Space
Fan Hangout at 3pm EST, where we will have Dr. Dan Coe, a member of the CLASH team with
us to further talk about his discovery.
So please take some time to tune in or leave a comment on this video if you can't make
it but want to ask a question, I'll go through them before we start to make sure they get
asked.
That's it for this week Space Fans, thank you for watching and as always, Keep Looking
Up.