Cropped view of Spiral Galaxy M51, demonstrating the excellent sharpness of the One Degree Imager (ODI) on the WIYN 3.5-m telescope on Kitt Peak.
Image credit: K. Rhode, M. Young and WIYN/NOAO/AURA/NSF.
Stars over the WIYN 3.5-meter telescope on Kitt Peak National Observatory.
Image credit: P. Marenfeld/NOAO/AURA/NSF
The Whirlpool Galaxy (Messier 51) has been a popular night sky target
for astronomers for centuries. Charles Messier first identified it in
1773 and listed it as number 51 in his catalog. To him, it looked like a
faint, fuzzy object that might be a comet. William Parsons, the 3rd
Earl of Rosse, used his 72-inch telescope “Leviathan” to observe the
Whirlpool in 1845. Since then, Messier 51 has likely been targeted by
virtually every telescope in the northern hemisphere. It is found in
the constellation Canes Venatici (the Hunting Dogs) and is a classic
example of a spiral galaxy.
Now, a new camera on the WIYN 3.5-meter telescope at Kitt Peak
National Observatory has imaged the Whirlpool Galaxy anew. The wide
field of the One Degree Imager (ODI) camera makes it possible to capture
the entire galaxy and its companion in one pointing, something that
even the Hubble Space Telescope cannot do.
Indiana University (IU) astronomy professor Katherine Rhode led this
effort as part of an imaging survey of spiral and elliptical galaxies.
The survey is aimed at understanding how these so-called “giant
galaxies” form and evolve.
“The WIYN telescope is an ideal telescope for the
survey because of its wide field and because it produces some of the
sharpest, highest-quality images possible with a ground-based
telescope”, explained Rhode. “WIYN’s 3.5-meter mirror is also very
efficient at gathering light from astronomical objects, so it allows us
to image faint objects, like individual star clusters within the
galaxies.”
This new image, as well as over one thousand others, can be found on
the National Optical Astronomy Observatory (NOAO) image gallery http://www.noao.edu/image_gallery/.
The gallery contains images taken with all the telescopes supported by
NOAO, selected videos, and pictures of telescopes and instruments.
An important consideration for imaging with ground-based telescopes
is what astronomers refer to as “seeing”, and most people think of as
stars twinkling. Twinkling is caused by movement of air in the Earth’s
atmosphere, and it can be minimized at a good telescope site, like on a
mountaintop in a dry climate. As WIYN Interim Director Dr. Eric Hooper
said, “The WIYN telescope on Kitt Peak is known for producing
excellent, steady images with high resolution, or sharpness.”
The WIYN ODI camera spent about an hour observing M51 through three
different filters: blue, green, and red. These digital images were
later combined to construct a “true-color” image: redder objects in the
image are cooler, emitting most of their light at longer optical
wavelengths, while bluer objects in the image are bluer and hotter in
reality. Objects that glow green are somewhere in between. Even though
the galaxy is almost 30 million light years away, the image clearly
shows clusters of young, hot stars that light up the spiral arms.
Threaded through the arms are dark “dust lanes”, where sooty material
left over from previous generations of stars has settled. More dust
lanes can be seen in the bridge of luminous stars and gas that connects
Messier 51 to its companion, the peculiar galaxy NGC 5195, in the upper
part of the image.
The images were taken by Dr. Rhode in May 2013 and then processed by
the ODI Portal, Pipeline, and Archive (ODI-PPA) project team at IU. The
ODI-PPA project is a collaboration between IU’s Pervasive Technology
Institute (PTI), the Science Data Management group at NOAO, and WIYN.
Arvind Gopu, ODI-PPA project manager, noted: “When requested by a
pipeline operator, ODI data are processed and archived using NSF-funded
cyberinfrastructure located at IU. In the case of the M51 images, our
lead developer Michael Young ran the raw images through the calibration
pipeline and used that data to make the final true-color images.”
The ODI camera is funded by the WIYN partners, and the National
Science Foundation, through its Telescope System Instrumentation
Program. The WIYN partners are University of Wisconsin, Indiana
University, Yale University, and the National Optical Astronomy
Observatory (NOAO). NOAO is operated by Association of Universities for
Research in Astronomy Inc. (AURA) under a cooperative agreement with
the National Science Foundation.
Science Contact:
Dr. Katherine L. Rhode
Indiana University Dept. of Astronomy
Bloomington, IN 47405
e-mail: rhode@astro.indiana.edu
Dr. Katherine L. Rhode
Indiana University Dept. of Astronomy
Bloomington, IN 47405
e-mail: rhode@astro.indiana.edu
