Transcript hubble_refurb

Results from the Refurbished Hubble
10/29/09
The Mission
• STS-125: 5/11/09 – 5/24/09
• Fifth and final servicing mission to the 19year old scope
• 3 members of 7-person crew had been on
earlier HST service missions
• The 2/1/03 Columbia disaster cancelled
the HST mission that had been schedule
for late 2005
Mission Reinstatement (Wikipedia)
Joining Mikulski as an advocate for servicing Hubble was NASA's Chief
Scientist, physicist John Grunsfeld, who was present at the meeting
when O'Keefe announced the cancellation of the mission.[18] A veteran
astronaut of four shuttle missions, including two Hubble servicing
missions, Grunsfeld had devoted years to Hubble, and was very
disappointed when O'Keefe canceled the mission.[18] He briefly
considered retiring from NASA, but realized if he stayed, he could
continue to advance physics in other ways.[18] Instead, Grunsfeld
dedicated himself to finding alternate ways to service the telescope,
possibly by sending a robot into orbit to do the job.[18] When O'Keefe
announced his resignation as Administrator in December 2004, five
days after a National Academy of Sciences committee opposed
O'Keefe's position regarding servicing Hubble,[19][20] the media and
science community saw hope for the telescope's servicing mission to
be reinstated.[21][22][Zimmerman 1]
More . . .
O'Keefe's replacement, former NASA Administrator Michael D. Griffin took just
two months after his appointment to announce that he disagreed with O'Keefe's
decision, and would consider sending a shuttle to repair Hubble.[Zimmerman 2]
As an engineer, Griffin had previously worked on Hubble's construction, and
respected the discoveries the telescope brought to the science
community.[Zimmerman 2] He agreed with the National Academy of Sciences
that a robotic mission was not feasible, and said that in light of the Return to
Flight changes made following the Columbia accident, a shuttle mission to
repair Hubble should be reassessed.[Zimmerman 3] After the successes of the
Return to Flight STS-114 and STS-121 missions, and the lessons learned and
improvements made following those missions, managers and engineers
worked to formulate a plan that would allow the shuttle to service Hubble, while
still adhering to the post-Columbia safety requirements.[Zimmerman 1]
On October 31, 2006, Griffin announced that the Hubble servicing mission was
reinstated, scheduled for 2008, and announced the crew that would fly the
mission, which included Grunsfeld.[NASA 9][23][24]
Mission Service Activities
• Replaced WFPC2 with WFC3
• Replaced Science Instrument Command and
Data handling Unit
• Replaced three gyros and two battery modules
• Removed COSTAR and replaced it with COS
• Replaced electronics for ACS
• Replaced electronics for STIS
• Other replacements of supporting equipment
Instrumentation
• COSTAR was the corrective device installed on
the first service mission. Later instruments have
been designed with their own corrective optics.
• WFC3: Optical wavelengths with 2 CCD’s;
(1024)2 near-IR array, 800 to 1700 nm.
• ACS: Used for the HUDF before it broke in 2007.
STS-125 restored the WFC, which registers 350
– 1100 nm.
The Wide Field Camera 3 (WFC3), a new camera aboard the Hubble Space Telescope, snapped
this image of the planetary nebula, catalogued as NGC 6302, but more popularly called the Bug
Nebula, or Butterfly Nebula. NGC 6302 lies within the Milky Way, roughly 3,800 light-years away in
the constellation Scorpius. The glowing gas is the star’s outer layers, expelled over about 2,200
years. The “butterfly” stretches for more than 2 light-years, which is about half the distance from the
Sun to the nearest star, Alpha Centauri. Image and caption: NASA, ESA, and the Hubble SM4 ERO
Team
These two images of a huge pillar of star birth demonstrate how observations taken in visible
(top) and in infrared light (bottom) by Hubble reveal dramatically different and complementary
views of an object. Composed of gas and dust, the pillar resides in a tempestuous stellar
nursery called the Carina Nebula, located 7,500 light-years away in the southern constellation
Carina. Image and caption: NASA, ESA, and the Hubble SM4 ERO Team
Hubble snapped this panoramic view of a colorful assortment of 100,000 stars residing in the crowded
core of a giant star cluster. The image reveals a small region inside the massive globular cluster
Omega Centauri, which boasts nearly 10 million stars. Globular clusters, ancient swarms of stars united
by gravity, are the homesteaders of our Milky Way. The stars in Omega Centauri are between 10 billion
and 12 billion years old. The cluster lies about 16,000 light-years from Earth.
Image and caption: NASA, ESA, and the Hubble SM4 ERO Team
A clash among members of a
famous galaxy quintet reveals an
assortment of stars across a wide
color range, from young blue stars to
aging red stars. This portrait of
Stephan’s Quintet, also known as
Hickson Compact Group 92, was
taken by the new Wide Field Camera
3. Stephan’s Quintet, as the name
implies, is a group of five galaxies.
The name, however, is a bit of a
misnomer. Studies have shown that
group member NGC 7320, at upper
left, is actually a foreground galaxy
about seven times closer to Earth
than the rest of the group.
Image and caption: NASA, ESA, and
the Hubble SM4 ERO Team
The wispy, glowing, magenta structures in this image are the remains of a star 10 to 15 times the mass of the Sun that we would have seen
exploding as a supernova 3,000 years ago. The remnant’s fast-moving gas is plowing into the surrounding gas of the galaxy, creating a
supersonic shock wave in the surrounding medium and making the material glow. The Hubble visible-light image reveals, deep within the
remnant, a crescent-shaped cloud of pink emission from hydrogen gas and soft purple wisps that correspond to regions of glowing oxygen. A
dense background of colorful stars is also visible. Probing this tattered gaseous relic, the newly installed Cosmic Origins Spectrograph (COS)
aboard NASA’s Hubble Space Telescope detected pristine gas ejected by the doomed star that has not yet mixed with the gas in the
interstellar medium. The supernova remnant, called N132D, resides in the Large Magellanic Cloud, a small companion galaxy of the Milky Way
located 170,000 light-years away. The resulting spectrum, taken in ultraviolet light, shows glowing oxygen and carbon in the remnant.
Image and caption: NASA, ESA, and the Hubble SM4 ERO Team
The Hubble Space Telescope’s newly repaired Advanced Camera for Surveys (ACS) has peered nearly 5 billion
light years away to resolve intricate details in the galaxy cluster Abell 370. Abell 370 is one of the very first
galaxy clusters where astronomers observed the phenomenon of gravitational lensing, where the warping of
space by the cluster’s gravitational field distorts the light from galaxies lying far behind it. This is manifested as
arcs and streaks in the picture, which are the stretched images of background galaxies. Gravitational lensing
proves a vital tool for astronomers when measuring the dark matter distribution in massive clusters, since the
mass distribution can be reconstructed from its gravitational effects.
Image and caption: NASA, ESA, and the Hubble SM4 ERO Team
This image of barred spiral galaxy NGC 6217 is the first image of a celestial object taken with the newly
repaired Advanced Camera for Surveys (ACS) aboard the Hubble Space Telescope. The camera was
restored to operation during the STS-125 servicing mission in May to upgrade Hubble.
The barred spiral galaxy NGC 6217 was photographed on June 13 and July 8, 2009, as part of the initial
testing and calibration of Hubble’s ACS. The galaxy lies 6 million light-years away in the north
circumpolar constellation Ursa Major. Image and caption: NASA, ESA, and the Hubble SM4 ERO Team
Background Info: Redshift vs Distance atlasoftheuniverse.com
Photometric Filters
ID
λeff[2]
FWHM[2]
Variant(s)
ID
λeff[2]
FWHM[2]
Variant(s)
U
365nm
66nm
u, u', u*
Y
1020nm
120 nm
y
B
445nm
94nm
b
J
1220nm
213nm
J', Js
V
551nm
88nm
v, v'
H
1630nm
307nm
g, g'
K
2190nm
390nm
K Continuum, K', Ks,
Klong, K8, nbK
G
R
658nm
138nm
r, r', R', Rc, Re,
Rj
L
3450nm
472nm
L', nbL'
I
806nm
149nm
i, i', Ic, Ie, Ij
M
4750nm
460nm
M', nbM
Z
912nm
z, z'
N
N1, N2, N3
Q
Q'
Lyman Hydrogen Spectrum (WP)
Lyman-α Forest (WP)
Gunn-Peterson Trough
(Becker, et. al.)
The Lyman Break
• Lyman-break galaxy A galaxy with a very high redshift
discovered from its red colour. Hydrogen is very effective
at absorbing radiation with wavelengths shorter than
91.2 nm (the Lyman limit), and all galaxies contain large
amounts of hydrogen; hence galaxies are virtually dark
at wavelengths shorter than 91.2 nm. This dividing point
in a galaxy's spectrum is termed the Lyman break. For a
galaxy at a redshift of about 3, the Lyman break falls
between the U and B photometric bands. The galaxy
should therefore be seen in B but be virtually invisible in
U, an effect called the U-band dropout. Encyclopedia.com
Lyman Break Galaxies
Steidel, Hamilton, Pettini, Dickinson, Giavalisco and their collaborators
The Article
• The filters: Y-band 1.1 um on the WFC3 and z’band 0.85 um on the ACS (previous).
• Look for z’-drops: (z’ – Y)AB > 1.3 and YAB < 28.5
• Use the WFC3 J-band image to reject low mass
galactic stars
• Calculate the star formation rate density for the
candidate galaxies
• Are the rates sufficient for reionization?
Figures
• (1): z’-drops of the 12 candidates. See
Table 1.
• (2): (z’ – Y) values at increasing redshifts.
Low redshift galaxies and dwarf stars can
also appear above the 1.3 cutoff.
• (3): LRG’s and dwarfs can be segregated
with additional photometry
• (4): Identifies the candidates
Figures (cont.)
• (5): “Hence we strongly rule out the
simple scenario of no evolution over the
range z = 7 - 3 as the observed counts are
3 - 5 times too low
• (6): Blueness of the z’-drops. “Such blue
slopes could be explained through low
metallicity, or a top-heavy IMF . . .”
(Interplanetary magnetic field)
• (7): z = 8(+) Y-drops
Estimates of Star Formation Rates
• “We can use the observed Y-band
magnitudes of objects in the z’-drop
sample to estimate their star formation
rate from rest-frame UV luminosity
density.” (Relation provided on p 9).
Results
• “. . . But even if we take fesc = 1 [] and a
very low clumping factor, this estimate of
the star formation density required (for
reionization) is a factor of 1.5 - 2 higher
than our measured star formation density
at z = 7 from z’-drop galaxies in the UDF.”