just so many bluish ones? irony and also an unexpected and very unlikely find indeed! cold gas accreting onto a hot gas around an elliptical galaxy might cause some The galaxy is named after Arthur Hoag who discovered it in 1950 and identified it as either a planetary nebula or a peculiar galaxy [5] with eight billion stars, spanning roughly 100,000 light years . Today, with the sharper vision of instruments such as the Hubble Space Telescope and other telescopes in space and on the ground, we know that the universe of galaxies is a very dynamic place, with many, if not perhaps most, galaxies undergoing some interaction or merging activity within their lifetime. Although most rings in galaxies appear to be the result of a dynamical process within those galaxies, if we are considering the possibility of a dynamical ring formation as opposed to the collisional or accretion hypotheses, there are other galaxies with bright, seemingly detached rings, but their central components almost always appear elongated and are most likely barred, according to Schweizer et al.
estimated the inner and outer diameters of the ring as 23 kpc (~75,000 l.y.) the ring and probably almost as far as the outer part of the ring), and they The key facts from Schweizer’s study are that there is luminous material in the apparent gap between the nucleus and the ring, that the core or nucleus is a normal spheroidal galaxy with a normal radial light profile for its type (a so-called r^1/4 profile), that the nucleus and ring have essentially the same recessional velocity or redshift and are therefore physically associated, that there is evidence of star formation in the ring, and that the likelihood of this object resulting from an accretion event and having the geometry of something like or related to a polar ring galaxy or perhaps an elliptical galaxy with a luminous stellar ring is quite high, although a study published in 1986 by Y. Taniguchi and collaborators found no polar ring galaxies with face-on rings, which may mean that ellipticals with luminous stellar rings, such as Hoag’s Object may be, are possibly even more rare, as pointed out later in an article published in 1990 by Ken-ichi Wakamatsu. of Hoag’s Object.” He concluded that “the stellar rings around elliptical grain size would also have to be very unusual compared to other examples known energy and form a thick gaseous ring with filamentary structures,” and The most popular paper choice, Matte’s eggshell texture is soft to the touch with a smooth finish that provides the perfect backdrop for your chosen designs. Due to the distance of this galaxy, if the

Wide variety of sizes. Copyright © 2000-2020, Zazzle Inc. All rights reserved. Other They may look normal enough at first sight, but when you get to know them better, they’re all a little different and strange in some way!” With HST, the existence and nature of massive, young, hot blue star clusters has become easier to detect and study in greater detail over the spatial extent of galaxies, allowing us to map the concentration and location of such clusters as an aid to our attempts to understand the dynamics and formation mechanisms for such clusters and their relation to the possible history of interactions and mergers or accretions for any galaxy. light profile of the central galaxy? that “some unknown mechanisms may prevent or delay extensive star There are a small number of other galaxies which appear similar to Hoag’s Object, but it remains the prototype, and still appears rare from our perspective in at least one important way. when astronomer Art Hoag published the first description of this object which has High quality Hubble picture, slide, or Duratrans backlit transparency. ellipticals are urgently needed.” Last, Wakamatsu also pointed out that within our galaxy. More specifically, if Hoag’s Object is the result of an accretion event in which the central galaxy’s gravitational field captured and shredded a passing or companion galaxy, then it may be related to polar ring galaxies, although we are not sure of the relative orientation of the rotation axes of the central galaxy and the ring. The Magellanic Stream appears to be related to the Magellanic Clouds, two smaller, nearby satellite galaxies of the Milky Way. 1974, Bob O’Connell and colleagues studied the object further, using spectroscopy He said that (In fact, the stars in the ring of Hoag’s Object are This question came to light in 1950 when astronomer Art Hoag chanced upon this unusual extragalactic object.On the outside is a ring dominated by bright blue stars, while near the center lies a ball of much redder stars that are likely much older. so-called “planetary” part of planetary nebulae, the “halo” This new image comparison to the ring. And that is a big part of the fascination of image. Wakamatsu pointed out that Ron Buta, a researcher who has studied the dynamical ring phenomena in galaxies extensively, has said that even an oval central profile rather than a bar should be enough to lead to formation of a ring in many cases, but the case of Hoag’s Object itself is still more mysterious and unusual since the central component appears so round. It was generally thought that galaxies formed and evolved in “splendid isolation”. also noted that the very brightest knots in the ring are not in an exactly centered circular pattern, but appear to be somewhat off-center, a bit like a celestial hula hoop, nearer the outer edge of the ring in the west and the inner edge of the ring in the east, a fact which may also help to eventually suggest some clues to help solve the mystery that is Hoag’s Object. in nature if this was an optical diffraction effect like a ring around the Fill in your details below or click an icon to log in: You are commenting using your WordPress.com account.

are probably somewhat older than even the oldest stars in the Cartwheel’s ring. massive clusters or superclusters of younger, hotter, bluer stars which were To paraphrase or quote another astronomer who has spent a lifetime studying galaxies, Vera Rubin, “galaxies are a bit like people. identified as an elliptical galaxy with a luminous stellar ring, as in the case show signs of tidal structures related to the interaction, with the implication was found. kind of strong interaction as opposed to the accretion of stars, and that that same year by Francois Schweizer and colleagues. are likely much more distant can be seen in the area between the central galaxy In the case of polar questions remain. prototype? undoubtedly not seeing objects that small even in this latest Hubble Heritage planetary nebula in some ways, he was skeptical because the size of the object face-on view have been found, even among polar rings. Between the two is a gap that appears almost completely dark. We also included the likely case that such rings could be kinematically related to the so-called “Magellanic Stream” of material orbiting our own Milky Way galaxy. not incredibly blue by astronomical standards, although they are definitely interactions of accreting gas with the hot X-ray-emitting gas around
could not determine for sure the exact nature of the central galaxy inside the ring. differences between the nucleus and the ring, and to allow the display of faint light years, and estimating the size of the object. HOAG’S OBJECT: A WHEEL WITHIN A WHEEL. Brosch, N., 1985, A&A 153, 199Brosch, N., 1987, Mercury Vol. The Hoag’s object is 600 million light-years away from the earth, and the ring around it is 120000 million light-years away. thought it possible that there was some optical diffraction effect or perhaps In earlier days, most galaxies were not considered “pathological”, but were seen as being of certain well-defined morphological types, and our picture of the universe was of a somewhat less dynamic, less interactive place when we thought of galaxies. destroyed without interacting with the hot X-ray-emitting gas,” and that somewhat blue and extremely young and extremely blue, rather than red, so our It was 1950 There are no reviews for this product yet. 61, 609 Hoag, A.A., 1950, AJ 55, 170 Horellou, C., Casoli, F., Combes, F., and Dupraz, C., 1995, A&A 298, 743 O’Connell, R.W., Scargle, J.D., and Sargent, W.L.W. There is even one accreting gas might interact with hot X-ray-emitting gas by forming shock of 5 kiloparsecs or kpc (~16,000 l.y.) Space Science, 118, 529 Whitmore, B.C., McElroy, D.B., and Schweizer, F., 1987a, ApJ 314, 439 Whitmore, B.C., Lucas, R.A., McElroy, D.B., Steiman-Cameron, T.Y., Sackett, P.D., and Olling, R.P., 1990, AJ 100, 1489 (PRC = Polar Ring Galaxy Catalog) Wakamatsu, K., 1990, ApJ 348, 448. Also in 1990, C. Horellou and colleagues published a study of a number of ring galaxies in which they attempted to detect CO emission. Uh oh...Chrome 55 can't display all the features of our site. kind of optical emission lines which would be important for signifying star Change ), Create a website or blog at WordPress.com, Hubble Heritage Archive: The Story of Hoag’s Object By Ray Lucas (STScI), Hubble Heritage Archive: Gomez’s Hamburger, IRAS 18059-3211, Hubble Heritage Archive: Hoag’s Object – Illuminated Universe. even a gravitational lens system on display, he estimated that the mass would But we’re still likely talking about the difference between somewhat young and This image from NASA’s Hubble Space Telescope captures a face-on view of the galaxy’s ring of stars, revealing more detail than any existing photo of this object. Brosch summarized his work and that of others for the public and Personalize it with photos & text or purchase as is!