Instrumentation:
A Helpful Link: The Diffraction Limit
First Generation Instruments:
InfraRed Imager and Spectrometer (IRIS)
IRIS will be the first science instrument on TMT. It will perform spectroscopy at the
diffraction limitThe maximum resolution a telescope may have. through the use of Integral Field
Units (IFUs) over small fields of view. IFUs are devices that allow multiple simultaneous spectra to be
taken: either of many objects or of different places across the same large object (such as a galaxy or cluster). IRIS
will also require adaptive optics to operate at the diffraction limit, and therefore be interfaced with the Canadian
built NFIRAOS instrument. As a result of this, Canada is a minor part of IRIS, to do work on the interface between
it and NFIRAOS.
IRIS is of the highest priority because it best takes advantage of the capabilities of a 30 m telescope, and offers a
range of capabilities itself, which can be applied to a broad range of scientific areas. IRIS will be used in the study
of galaxies, black holes, and even solar system objects much closer to home.
In the study of the physics of galaxy formation, IRIS will be used to measure chemistry,
kinematicsThe study of motion without regard to the forces that cause it. and physical attributes of objects on scales of approximately
326 light years from the peak of star formation onward. IRIS will also allow a better understanding of the nature of
supermassive black holes and their effects in the local universe, their formation and growth through the study of
stellar and gas orbits in the centers of galaxies. In addition to all this, IRIS will have better resolution and
sensitivity than many space missions of the past twenty years which can be applied to close study of the planets,
moons and asteroids in our own solar system.
IRIS will operate in the infrared part of the spectrum. See where that is.
Wide Field Optical Imager and Spectrometer
(WFOS)
In addition, the WFOS/TMT combination promises to revolutionize our
understanding of elliptical galaxies and their globular clusters, both through a comprehensive study of dark matter
distribution, but also through the first-ever investigation on how globular cluster orbital properties are dependent on
galaxy properties, the local environment, cluster age and chemical abundance.
WFOS will also be sensitive enough to determine the composition of the
intergalactic medium (IGM)The material (gas and dust) found between galaxies.
using galaxies as a background source, instead
of the luminous objects used now. The spectrum of the IGM is imprinted on the spectrum of the source as the IGM causes
absorbtion lines that should not be present for the background object. The use of galaxies is helpful they can be
detected independent of their luminosity.
Finally, WFOS will allow scientists to test physical constants to see if they have changed in value over the history of
the universe. It is usually assumed that physical constants have always retained the same value despite time or place
in the universe. Laboratory tests have provided constraints on time variability of the physical constants for the
present, however it is unclear whether the constants had the same value on the cosmological time scale of billions of
years. The discovery of the cosmological constantAn
ad hoc addition Einstein made to his theory of general
relativity so as to satisfy his presumption that the universe
was static. Later he referred to it as the greatest blunder in
his life as it prevented him from predicting the expansion of
our universe. It allows the universe to be static by making it
innately expanding in order to counteract gravitational
attraction. It can be interpreted as a constant energy density
of the vacuum of space. makes knowing
variability even more relevant as the cosmological constant has large effects on the behaviour of the universe. For
example, Einstein used it to give the universe an innate tendency to expand, thereby counteracting gravity to allow a
static universe, and then called it his biggest blunder when Edwin Hubble observed that the Universe is expanding.
The science results produced by WFOS will help to see how much we really know about physics today.
Near InfraRed Multi-Object Spectrograph (IRMOS)
IRMOS utilize adaptive optics and operate near the diffraction limit and use multiple
IFUsA device that allows multiple simultaneous spectra to be taken: either of different objects or of
different locations across the same large object. across its field of view to study multiple extended objects.
Extended objects are objects that are not points of light (like stars), but broad objects, such as galaxies. The
IFUs are expected to allow the spectroscopy of approximately 10-20 objects at once. This will allow sensitive
observations of extremely faint extended objects. IRMOS operates, as its name suggests, in the near infrared part of
the spectrum.
IRMOS will be used for a number of science goals, including the exploration of properties of galaxies during peak star
formation, the properties of extremely high redshift (extremely far away) galaxies, as well as being able to study faint
galaxies not undergoing star formation.
IRMOS will be able to provide detailed studies of chemistry, star formation rates and distributions, as well as the
kinematics of galaxies. IRMOS will also provide spectroscopic data allowing the interpretation of data gathered by JWST
surveys for extremely distant galaxies. Little is known about the evolution of galaxy properties, and other
characteristics from this era (the farther away telescopes look, the farther back in time they do as well). The
discoveries made by IRMOS will certainly help our understanding of galactic development and evolution.
Planet Formation Instrument (PFI)
The PFI is being developed by the Université de Montréal. It is designed with an extremely small field of
view and will be used to take the spectra of extrasolar planets. PFI will operate near diffraction limit, and be
capable of high-contrast imaging as well, for the direct detection of these extrasolar planets. See where PFI operates
in the electromagnetic spectrum.
This instrument involves the use of an IFU to aid with taking spectra. PFI also makes use of a coronograph to reduce
the light from the parent star, and a natural guide star adaptive optic system to allow the instrument to work at
near-diffraction limit.
PFI will contribute to two main science areas: direct detection of giant planets around young stars, and the
characterization of giant planet atmospheres. Gas giant planets are expected to be self-luminous in near-infrared
wavelengths at birth and then rapidly fade. Fof example, a planet five times the mass of Jupiter would be detectable
with PFI for 200 million years. PFI will be able to survey for these planets to a distance of 150 parsecs, or
approximately 489 light years.
Using the IFU, PFI will be able to take spectra of the light from etra-solar planets. This will allow scientists
to determine chemical abundances, physical characteristics and even allow them to make inferences about the interiors
of theplanets observed. Understanding extrasolar planets not only helps us understand more about the universe around
us, but helps to determine whether our solar system is unique or normal.
Mid InfraRed Echelle Spectrometer (MIRES)
MIRES will obtain high resolution spectra to study protostars and protoplanetary disks. To do this, an adaptive optic
system will be used to operate at the diffraction limit. This will be controlled by both laser and natural guide star
systems. It uses an echelle spectrograph, which means it uses a special kind of
diffraction gratingA device that splits light into its different wavelengths (i.e. colours), called a spectrum of light. called an echelle to break the light collected into
its constituent colours. See what part of the spectrum MIRES will use.
MIRES will study the dissipation of gas in planet-forming disks, for both terrestrial (rocky planets like Earth) and
giant planet (such as Jupiter or Saturn) regions for a range of ages and situations to determine how planet-forming
environments evolve. It will also work to indirectly identify forming planets in protoplanetary disks by inferring the
presence of gaps caused by forming planets. Lastly, MIRES will be used to study the structure and kinematics about
protostar envelopes. This means that MIRES will investigate what happens when material falls into a star leading to its
growth. As with some of the other instruments, MIRES will help scientists to understand the development of solar
systems.
Narrow Field InfraRed Adaptive Optic
System (NFIRAOS)
TMT is designed so that adaptive optics correct the light it collects before sending it to the instruments that
take scientific data. The instrument that does this is NFIRAOS. NFIRAOS is designed to compensate for atmospheric
turbulence using a laser guide star adaptive optics system. This will help to allow the telescope to operate at the
diffraction limit. NFIRAOS will also correct for wavefront aberrations caused by imperfections in both the science
instrument and telescope optics, thereby improving overall information function.
NFIRAOS will also incorporate natural guide star tip/tiltProperties that determine where the centre of an image lands on a detector.
A flat mirror can correct for this property. wavefront
sensors to maximize sky coverage and be designed to be upgraded to multi-conjugate adaptive optics for use with a
wider field of view.
NFIRAOS is being developed at NRC-HIA, where it has been determined that the instrument is feasible. This design study is
scheduled slightly ahead of the other instruments. This is to allow information such as about inferfaces to be obtained
from it in time to be applied to detailed instrument studies. This is important because, as mentioned before, NFIRAOS
will be interfaced with many of the science instruments.
To Second Generation Instruments
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