Hello Space Fans and welcome to another edition of Space Fan News.
This week, Hubble observes the most distant galaxy ever seen; the twin black holes observed
by LIGO may have come from the same star; and ESA’s EXOMARS Mission prepares to launch
later this month.
Astronomers using the Hubble Space Telescope have announced they they have observed and
confirmed the most distant galaxy ever detected.
By pushing Hubble to its limits, an international team has shattered the cosmic distance record
by measuring the farthest galaxy ever seen in the universe.
This surprisingly bright, infant galaxy, named GN-z11, is seen as it was 13.4 billion years
in the past, just 400 million years after the big bang.
GN-z11 is located in the direction of the constellation of Ursa Major.
With this observation, astronomers are closing in on the first galaxies that formed in the
universe and take astronomers into a realm that was once thought to be only reachable
with NASA's upcoming James Webb Space Telescope.
This measurement provides strong evidence that some unusual and unexpectedly bright
galaxies found earlier in Hubble images are really at extraordinary distances.
Previously, the team had estimated GN-z11's distance by determining its color through
imaging with Hubble and the Spitzer Space Telescope,
This method of using filters to estimate distance is called called photometric redshift.
Now, for the first time for a galaxy at such an extreme distance, the team used Hubble's
Wide Field Camera 3 to precisely measure the distance to GN-z11 spectroscopically by splitting
the light into its component colors.
This spectroscopic redshift is a much more accurate and definitive measurement for determining
distance.
The problem is it requires more light to make and these very distant galaxies are barely
within Hubble’s vision.
But GN-z11 was unusually bright for a galaxy so far away and the WFC3 spectrograph was
able to make the measurement.
Now for those who don’t know, Astronomers measure large distances by determining the
"redshift" of a galaxy.
This phenomenon is a direct result of the expansion of the universe; every distant object
in the universe appears to be going away from us because its light is stretched to longer,
redder wavelengths as it travels through expanding space to reach our telescopes.
The greater the redshift, the farther away the galaxy is.
Astronomers say these spectroscopic observations reveal the galaxy to be even farther away
than had been originally thought, right at the distance limit of what Hubble can observe.
In the past, using the photometric redshift observations, astronomers determined the distance
for GN-z11 had a redshift of 8.68 (13.2 billion years in the past).
Now, with the spectroscopic observations, the team has confirmed GN-z11 actually has
a redshift of 11.1, nearly 200 million years closer to the time of the big bang - shattering
all previous record holders.
So what’s this galaxy like and why was it so bright?
Well, these observations show a very young and hot galaxy, creating stars at a furious
rate.
The combination of Hubble and Spitzer imaging reveals that GN-z11 is 25 times smaller than
the Milky Way and has just one percent of our galaxy's mass in stars.
But, this newborn galaxy is also growing very fast and is forming stars at a rate about
20 times greater than our galaxy does today.
This makes such an extremely remote galaxy bright enough for astronomers to find and
perform detailed observations with both Hubble and Spitzer.
This was an unexpected thing to see from such a distant galaxy and these results reveal
surprising new clues about the nature of the very early universe.
It was surprising to see that a galaxy so massive existed only 200 to 300 million years
after the very first stars started to form.
Now astronomers are saying that these findings provide a tantalizing preview of the observations
that the James Webb Space Telescope will perform after it is launched in 2018.
Hubble and Spitzer are already reaching into Webb territory and this new discovery shows
that the JWST will surely find many such young galaxies reaching back to when the first galaxies
were forming.
I’ll let you know…
Next, remember a couple of weeks ago I told you about the discovery of gravitational waves
and that the source of those waves were created from the merging of two stellar-sized black
holes?
Well, astronomers are now saying that it’s possible that those two black holes were formed
from within a single star.
When two black holes merge, most people think that the event would be dark, right?
I mean if two black things that emit no light of their own collide, then the resulting collision
would also be dark.
Well, turns out that’s not always true.
Observations from the Fermi Space Telescope - a gamma ray telescope - detected a gamma-ray
burst just a fraction of a second after LIGO's famous signal detection.
Having this bright event occur immediately after the gravitational wave event suggests
that the two black holes might have resided inside a single, massive star whose death
generated the gamma-ray burst.
Now normally, and we’ve talked about this a lot on SFN, when a very massive star reaches
the end of its life, its core collapses into a single black hole.
But if the star was spinning very rapidly as it collapses, its core might stretch into
a dumbbell shape and fragment into two clumps, each forming its own black hole.
So how can this happen?
Well to start you need an very massive star that’s spinning really fast and to get that
spin, it usually means you start with two smaller stars revolving around each other.
As they revolve around each, they go faster and faster as they spiral together and the
resulting merged star would still be spinning after it’s over.
Really fast
Next, after the rapidly spinning star collapses squishing what would normally be one core
out and - because of the spinning - eventually splits into two, creating the rapidly spinning
black hole pair.
What’s left after all of this, the star's outer envelope, then starts rushing inward
toward them and it’s that material that would fuel the gamma ray burst just a few
thousandths of a second later.
In order to power both the gravitational wave event and the gamma-ray burst, the twin black
holes had to have been born close together, with an initial separation of order the size
of the Earth, and they merged within minutes.
The newly formed single black hole then fed on the infalling matter, consuming up to a
Sun's worth of material every second and powering jets of matter that blasted outward, creating
the gamma ray burst a fraction of a second later.
Now I don’t care who you are, that is Just Like Downtown.
Finally, ESA’s EXOMARS Trace Gas Orbiter and Schaiparelli Mission gets ready to launch
later this month.
The EXOMARS program consists of of an orbiter designed to look at Mars’ atmosphere and
a decent and landing demonstrator module, known as Schiaparelli.
The main objectives of this mission are to search for evidence of methane and other trace
gasses that could be signatures of active biological or geological processes on Mars
and to test key technologies in preparations for future missions to Mars.
The Orbiter and Schiaparelli will be launched together, currently planned for March 14,
2016, and will go on a Proton rocket and will fly to Mars at the same time.
By taking advantage of the positioning of Earth and Mars the cruise phase can be limited
to only about 7 months, with the pair arriving at Mars later this year, in October 2016.
Three days before reaching the atmosphere of Mars, Schiaparelli will be ejected from
the Orbiter towards the Red Planet.
Schiaparelli will then coast towards its destination, enter the Martian atmosphere at 21 000 km/h,
decelerate using aerobraking and a parachute, and then brake with the aid of a thruster
system before landing on the surface of the planet.
From its coasting to Mars till its landing, Schiaparelli will communicate with the Orbiter.
Once on the surface, the communications of Schiaparelli will be supported from Mars Express
and from a NASA Relay Orbiter.
The ExoMars Orbiter will be inserted into an elliptical orbit around Mars and then sweep
through the atmosphere to finally settle into a circular, approximately 400-km altitude
orbit ready to conduct its scientific mission.
Schiaparelli will demonstrate a range of technologies to enable a controlled landing on Mars in
preparation for future missions.
The launch of ExoMars 2016 will mark the start of a new era of Mars exploration for Europe.
Later in 2018, the EXOMARS mission will include a rover that will carry a drill and a suite
of instruments dedicated to exobiology and geochemistry research.
I’ll let you know.
Well, that’s it for this week Space Fans, thank you all for watching and thanks to all
of you who support SFN on Patreon to make it better, and as always, Keep Looking Up!