Modern Astronomy and Subaru
SUBARU: An Optical Infrared Telescope
The expanding universe experiences a variety of dynamic phenomena such as the births and deaths of stars or spectacular galaxy collisions. Subaru Telescope’s capabilities offer different modes of observation, no matter the complexity of an object or event an astronomer wishes to study.
A Ground-based Telescope and a Space Telescope
Visible light image of galaxy M82 taken by FOCAS at Subaru. The red filamentary features extending perpendicular to the galaxy are due to ionized hydrogen gas emitting its characteristic red light.
Ground-based and orbiting telescopes work to fulfill different needs and roles. Subaru Telescope can observe the part of the electromagnetic spectrum that has a high atmospheric transmission rate. This waveband includes visible light, near-infrared, and mid-infrared waves. Of course, some of the highest resolution observations in infrared, optical, ultraviolet, X-ray, and γ-wavelengths come from space-based observatories (located well away from interference by Earth’s atmosphere) such as the Hubble Space Telescope, Spitzer Space Telescope, and the Chandra X-ray Satellite.
Currently, the resolving power of ground-based telescopes is lower than that of space-born observatories such as Hubble Space Telescope. However, this is quickly changing due to several advances. Observation in the near-infrared using adaptive optics (see page 10) has greatly reduced the negative effects of atmospheric disturbance. As adaptive optics continues to develop and improve, it may be possible that some day ground-based telescopes will exceed the resolution available from space telescopes. Ground-based facilities can have much greater light-gathering capacity than space-born facilities whose mirror sizes are limited by the payload that can be sent to space.
Currently, for observations in the mid-infrared (radiation of heat produced by the interaction of dust and nearby stars), ground-based telescopes already exceed orbiting facilities in terms of resolving power because of their larger diameter. Another critical advantage of ground-based telescopes is their ability to add cutting-edge technology at little cost, particularly when compared to launching a mission to affect an upgrade to a space-based telescope.
Spectroscopic observations, where light is divided into different wavelengths, are essential when analyzing the characteristics of an object or to determine its distance. Such observations are where larger ground-based telescopes such as Subaru are making great contributions.
There are ten 8-meter class ground-based telescopes in the world today (with several more in construction) and each has its own unique characteristics. Astronomers use information from these telescopes in collaboration with other observatories and wavelengths to continue to understand the mysteries of the universe.
An X-ray image of the central region of galaxy M82 taken by NASA Chandra satellite. The bright areas indicate X-ray radiation being emitted from a black hole.
Near-infrared image (Subaru Telescope-CISCO)
Radio image (Nobeyama Radio Observatory)
A complete picture of the object is revealed by different wavelength observations.