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Forfatter/Opretter: Urutseg, Licens: CC BY-SA 3.0
Astronomy stub

NGC 4589 Hubble WikiSky.jpg
NGC 4589 galaxy by Hubble space telescope

NGC 1512.jpg

NGC 1512

About This Image

In this view of the center of the magnificent barred spiral galaxy NGC 1512, NASA Hubble Space Telescope's broad spectral vision reveals the galaxy at all wavelengths from ultraviolet to infrared. The colors (which indicate differences in light intensity) map where newly born star clusters exist in both "dusty" and "clean" regions of the galaxy.

This color-composite image was created from seven images taken with three different Hubble cameras: the Faint Object Camera (FOC), the Wide Field and Planetary Camera 2 (WFPC2), and the Near Infrared Camera and Multi-Object Spectrometer (NICMOS).

NGC 1512 is a barred spiral galaxy in the southern constellation of Horologium. Located 30 million light-years away, relatively "nearby" as galaxies go, it is bright enough to be seen with amateur telescopes. The galaxy spans 70,000 light-years, nearly as much as our own Milky Way galaxy.

The galaxy's core is unique for its stunning 2,400 light-year-wide circle of infant star clusters, called a "circumnuclear" starburst ring. Starbursts are episodes of vigorous formation of new stars and are found in a variety of galaxy environments.

Taking advantage of Hubble's sharp vision, as well as its unique wavelength coverage, a team of Israeli and American astronomers performed one of the broadest and most detailed studies ever of such star-forming regions. The results, which will be published in the June issue of the Astronomical Journal, show that in NGC 1512 newly born star clusters exist in both dusty and clean environments. The clean clusters are readily seen in ultraviolet and visible light, appearing as bright, blue clumps in the image. However, the dusty clusters are revealed only by the glow of the gas clouds in which they are hidden, as detected in red and infrared wavelengths by the Hubble cameras. This glow can be seen as red light permeating the dark, dusty lanes in the ring.

"The dust obscuration of clusters appears to be an on-off phenomenon," says Dan Maoz, who headed the collaboration. "The clusters are either completely hidden, enshrouded in their birth clouds, or almost completely exposed." The scientists believe that stellar winds and powerful radiation from the bright, newly born stars have cleared away the original natal dust cloud in a fast and efficient "cleansing" process.

Aaron Barth, a co-investigator on the team, adds: "It is remarkable how similar the properties of this starburst are to those of other nearby starbursts that have been studied in detail with Hubble." This similarity gives the astronomers the hope that, by understanding the processes occurring in nearby galaxies, they can better interpret observations of very distant and faint starburst galaxies. Such distant galaxies formed the first generations of stars, when the universe was a fraction of its current age.

Circumstellar star-forming rings are common in the universe. Such rings within barred spiral galaxies may in fact comprise the most numerous class of nearby starburst regions. Astronomers generally believe that the giant bar funnels the gas to the inner ring, where stars are formed within numerous star clusters. Studies like this one emphasize the need to observe at many different wavelengths to get the full picture of the processes taking place.

CREDITS: NASA, ESA, and D. Maoz (Tel-Aviv University and Columbia University)

KEYWORDS: GALAXIES SPIRAL GALAXIES

Fast Facts About The Object Object Name NGC 1512 Object Description Barred spiral galaxy R.A. Position 04h 3m 54.29s Dec. Position -43° 20' 56.0" Constellation Horologium Distance 9.2 million pc (30 million light-years) Dimensions The galaxy is 70,000 light-years across. The circumnuclear starburst ring is 2,400 light-years wide. About The Data Data Description Principal Astronomers: D. Maoz (Tel-Aviv University/Columbia University), A. J. Barth (Harvard CfA), L. C. Ho (Carnegie Obs.), A. Sternberg (Tel-Aviv University and A. V. Filippenko (UC Berkeley). Members of the group of scientists involved in these observations are: Dan Maoz (Tel-Aviv University, Israel and Columbia University, USA), Aaron J. Barth (Harvard-Smithsonian Center for Astrophysics, USA), Luis C. Ho (The Observatories of the Carnegie Institution of Washington, USA), Amiel Sternberg (Tel-Aviv University, Israel) and Alexei V. Filippenko (University of California, Berkeley, USA). Instrument HST>FOC, HST>NICMOS, and HST>WFPC2 Exposure Dates July 18, 1993 (FOC), July 29, 1998 (NICMOS), and March 5, 1999 (WFPC2)

Filters FOC: F220W (2200Å) WFPC2: F336W (U), F658N (redshifted Ha), F547M (Strömgren y), and F814W (I) NICMOS: F160W (1.6mm), and F187W (1.8mm)

Caldwell.png
Forfatter/Opretter: Roberto Mura, Licens: CC BY-SA 3.0
Collage of photos from Wikimedia Commons. Some Caldwell Catalogue's photos.

M81 Galaxy from the Mount Lemmon SkyCenter Schulman Telescope courtesy Adam Block.jpg
Forfatter/Opretter: Ngc1535, Licens: CC BY-SA 4.0
Deep exposures of Galaxies

using the 0.8m Schulman Telescope at the Mount Lemmon SkyCenter

Credit Line & Copyright Adam Block/Mount Lemmon SkyCenter/University of Arizona

Milky Way Galaxy.jpg
Artist's conception of the Milky Way galaxy.

UDFy-38135539-HST-eso1041b.jpg
Hubble Space Telescope image of galaxy UDFy-38135539. It is located in the constellation Fornax at coordinates 03 32 38.13 -27 45 53.9

IC 335 - Potw1451a.tif
(c) ESA/Hubble, CC BY 4.0
This new NASA/ESA Hubble Space Telescope image shows the galaxy IC 335 in front of a backdrop of distant galaxies. IC 335 is part of a galaxy group containing three other galaxies, and located in the Fornax Galaxy Cluster 60 million light-years away. As seen in this image, the disc of IC 335 appears edge-on from the vantage point of Earth. This makes it harder for astronomers to classify it, as most of the characteristics of a galaxy’s morphology — the arms of a spiral or the bar across the centre — are only visible on its face. Still, the 45 000 light-year-long galaxy could be classified as an S0 type. These lenticular galaxies are an intermediate state in galaxy morphological classification schemes between true spiral and elliptical galaxies. They have a thin stellar disc and a bulge, like spiral galaxies, but in contrast to typical spiral galaxies they have used up most of the interstellar medium. Only a few new stars can be created out of the material that is left and the star formation rate is very low. Hence, the population of stars in S0 galaxies consists mainly of aging stars, very similar to the star population in elliptical galaxies. As S0 galaxies have only ill-defined spiral arms they are easily mistaken for elliptical galaxies if they are seen inclined face-on or edge-on as IC 335 here. And indeed, despite the morphological differences between S0 and elliptical class galaxies, they share a some common characteristics, like typical sizes and spectral features. Both classes are also early-type galaxies, as they are evolving passively. However, elliptical galaxies may be passively evolving when we observe them, but they had violent interactions with other galaxies in their past. Whereas S0 galaxies are either aging and fading spiral galaxies, which never had any interactions with other galaxies, or they are the aging result of a single merger between two spiral galaxies in the past. The exact nature of these galaxies is still a matter of debate. Links Structure and Formation of S0 and Spheroidal Galaxies Can Early Type Galaxies Evolve from Fading the Disks of Late Types?

NGC 4414 (NASA-med).jpg
In 1995, the majestic spiral galaxy NGC 4414 was imaged by the Hubble Space Telescope as part of the HST Key Project on the Extragalactic Distance Scale. An international team of astronomers, led by Dr. Wendy Freedman of the Observatories of the Carnegie Institution of Washington, observed this galaxy on 13 different occasions over the course of two months. Images were obtained with Hubble's Wide Field Planetary Camera 2 (WFPC2) through three different color filters. Based on their discovery and careful brightness measurements of variable stars in NGC 4414, the Key Project astronomers were able to make an accurate determination of the distance to the galaxy. The resulting distance to NGC 4414, 19.1 megaparsecs or about 60 million light-years, along with similarly determined distances to other nearby galaxies, contributes to astronomers' overall knowledge of the rate of expansion of the universe. In 1999, the Hubble Heritage Team revisited NGC 4414 and completed its portrait by observing the other half with the same filters as were used in 1995. The end result is a stunning full-color look at the entire dusty spiral galaxy. The new Hubble picture shows that the central regions of this galaxy, as is typical of most spirals, contain primarily older, yellow and red stars. The outer spiral arms are considerably bluer due to ongoing formation of young, blue stars, the brightest of which can be seen individually at the high resolution provided by the Hubble camera. The arms are also very rich in clouds of interstellar dust, seen as dark patches and streaks silhouetted against the starlight.

ID: GPN-2000-000933

Other ID: PR99-25

Hubble2005-01-barred-spiral-galaxy-NGC1300.jpg
Barred spiral galaxy NGC 1300 photographed by Hubble telescope.

In the core of the larger spiral structure of NGC 1300, the nucleus shows its own extraordinary and distinct "grand-design" spiral structure that is about 3,300 light-years (1 kiloparsec) long. Only galaxies with large-scale bars appear to have these grand-design inner disks — a spiral within a spiral. Models suggest that the gas in a bar can be funneled inwards, and then spiral into the center through the grand-design disk, where it can potentially fuel a central black hole. NGC 1300 is not known to have an active nucleus, however, indicating either that there is no black hole, or that it is not accreting matter.

The image was constructed from exposures taken in September 2004 by the Advanced Camera for Surveys onboard Hubble in four filters. Starlight and dust are seen in blue, visible, and infrared light. Bright star clusters are highlighted in red by their associated emission from glowing hydrogen gas. Due to the galaxy's large size, two adjacent pointings of the telescope were necessary to cover the extent of the spiral arms. The galaxy lies roughly 69 million light-years away (21 megaparsecs) in the direction of the constellation Eridanus.

NGC 4013HSTPart.jpg
NGC 4013 closeup view

Irregular galaxy NGC 1427A (captured by the Hubble Space Telescope).jpg
The irregular galaxy NGC 1427A will not survive long as an identifiable galaxy, passing through the Fornax cluster at nearly 600 kilometers per second (400 miles per second). Galaxy clusters, like the Fornax cluster, contain hundreds or even thousands of individual galaxies. Within the Fornax cluster, there is a considerable amount of gas lying between the galaxies. When the gas within NGC 1427A collides with the Fornax gas, it is compressed to the point that it starts to collapse under its own gravity. This leads to formation of the myriad of new stars seen across NGC 1427A, which give the galaxy an overall arrowhead shape that appears to point in the direction of the galaxy's high-velocity motion. The tidal forces of nearby galaxies in the cluster may also play a role in triggering star formation on such a massive scale.