Búsqueda avanzada de imágenes

11 Septiembre 2007: An international team of researchers led by Natalia Boris of the University of São Paulo in Brazil has shown that quasar pairs may be excellent beacons for finding clusters of galaxies in the early universe. Quasars are relatively rare astronomical objects. If, as evidence suggests, their spatial distribution follows that of galaxies then the presence of two or more quasars in the same small volume of space might indicate a region that is exceptionally rich in galaxies. Deep multi-color images of four fields around quasar pairs (QP0110-0219, QP1310+0007, QP1355-0032, and QP0114-3140) at redshift z~1 were obtained with the Gemini Multi-Object Spectrograph (GMOS) at both Gemini North and South. The quasar pairs were selected to have redshift differences smaller than 0.01 and projected angular separations less than 300 arcseconds, corresponding to projected physical separations less than 2.5 megaparsecs. Examination of the quasar spectra confirmed that these are bona fide pairs of …

5 Septiembre 2007: At Gemini the night of July 4th, 2005 was filled with fireworks, both earthly and celestial. In support of NASA’s Deep Impact (DI) mission two teams of scientists used the Gemini mid-infrared instruments MICHELLE and T-ReCS to acquire imaging and spectroscopic observations of Comet Tempel 1 throughout the impact event. At Gemini South a team led by David Osip (Carnegie Inst.) and James De Buizer (Gemini) used T-ReCS to image the impact and the resulting dust plume (Figure 1). At Gemini North, David Harker (UCSD) led a team that used MICHELLE to obtain mid-infrared spectra Temple 1 over a three-night observing run. The Harker campaign was conducted in conjunction with a team using the mid-IR instrument COMICS on the Subaru telescope. By observing the comet pre-, and post-impact, the Harker team gathered baseline data sets to compare with data obtained during the moments surrounding impact. The results of the campaign …

29 Agosto 2007: As young stars form and evolve they generate spectacular high-speed jets and outflows consisting of molecular and atomic gas streaming away from the star. It is not completely understood what mechanisms launch these jets. This is partly because most of the action takes place in the inner, difficult to view, regions of the dense gas and dust accretion disk surrounding these forming stars. The best spatial and spectroscopic resolution is needed to dissect this region. A team led by Michihiro Takami (Subaru Telescope, now at ASIAA) and Tracy Beck (Gemini Observatory) have used the adaptive optics fed integral-field spectrograph NIFS on Gemini North to explore the inner structure of the jet in the young star HL Tau, located about 140 parsecs (460 light years) away in the constellation of Taurus. The morphology and kinematics in molecular hydrogen (H2) emission from HL Tau are found to be similar to millimeter wavelength …

17 Agosto 2007: Deep Gemini imaging of the cluster of galaxies Hydra I (also known as Abell 1060) at a distance of 54 Mpc (176 million light-years) has revealed an abundance of massive luminous metal-rich globular clusters that appears to impersonate ultra-compact dwarf galaxies. This is the richest population of such massive stellar systems ever found in any nearby galaxy clusters. This new finding by Elizabeth M. H. Wehner and William E. Harris (McMaster University, Hamilton, Canada) indicates that these massive stellar clusters may be transition objects between Ultra-Compact Dwarf (UCDs) galaxies and the more familiar massive globular clusters. UCDs are a recently discovered type of old stellar system – too faint and compact to be called normal dwarf elliptical galaxies, but too big and bright to be called conventional globular clusters. Small numbers of them have been identified and studied in the nearby Virgo and Fornax clusters of galaxies over the past …

31 Julio 2007: Linhua Jiang (Steward Observatory, University of Arizona) has led a United States/Germany team of astronomers in the study of some of the most distant and youngest known quasars. The six distant quasars they observed are at redshifts ranging between z = 5.8 to 6.3 and correspond to a period when the universe was only about one billion years old. Using the Gemini Near Infrared Spectrograph (GNIRS) at Gemini South and the Near-Infrared Imager (NIRI) at Gemini North, the team found these very young quasars to be already super-enriched in heavy elements. The quasars are also powered by extremely massive black holes. The Jiang et al. results cast a new light on the assembly of black holes and the chemical enrichment of the universe less than one billion years after the Big Bang. Quasars are the most luminous and most energetic objects in the universe. The stellar-like objects are surmised to …

27 Junio 2007: During a search for hydrogen emission in the disks of young stars, Suzanne K. Ramsay Howat (UK Astronomy Technology Centre) and Jane S. Greaves (University of St. Andrews) have discovered a massive layer of hot gas around a low-mass M3-type star in the 6 million-year-old Eta Chamaeleontis cluster. Both the strength and the kinematics of the emission imply that it arises from a disk illuminated by ultraviolet radiation produced by the central star. Studying the gas content of protoplanetary disks around young stars is an important step in understanding the formation of planetary systems. Molecular hydrogen is one of the main constituents of the atmospheres of giant planets and so must be present in the disks for Jupiter-like planets to form. Moreover, the near-infrared emission from it is one of the best indicators of warm gas that may exist in gaps carved by massive new protoplanets. This emission may arise …

18 Junio 2007: Amidst the stunning beauty of the Foz do Iguaçu park and waterfalls in Brazil, more than 130 astronomers and staff from the seven-country Gemini partnership converged during the week of June 11th, 2007 to discuss current results, capabilities and future research and collaborations. The Laboratório Nacional de Astrofísica (LNA), acting as the Brazilian National Gemini Office, was responsible for the local organization of the meeting. Foz de Iguaçu was chosen as the meeting place because it combines a desirable tourist attraction – the Iguaçu-Falls are among the most stunning natural displays on earth – with excellent infra-structure for international conventions. “We are very satisfied that the Gemini Board accepted the offer of LNA to host the Gemini Science Meeting in Brazil,” said Albert Bruch, chair of the Local Organizing Committee. “Among several options we choose a prime meeting place which from the very beginning gave us confidence that the participating …

25 Mayo 2007: Deep HST and Spitzer imaging of a passively evolving galaxy identified in the Gemini Deep Deep Survey (GDDS) has led to the detection of a very compact cluster of massive red galaxies at a redshift of z =1.51. For galaxies without emission lines this redshift is beyond the reach of most spectroscopic studies, however, the ultra-deep Gemini spectroscopy of the GDDS program detected continuum emission from the source which made it possible to establish the z = 1.51 redshift of the galaxy. Assuming that the other cluster members have the same redshift makes this one of the most distant clusters discovered to date. Subsequent HST and Spitzer imaging uncovered 12 galaxies within 170 kpc of the GDDS target proving that the newly discovered cluster is both compact and densely populated. This suggests that several of the cluster members will likely merge to form a single behemoth galaxy by the present …

15 Mayo 2007: GNIRS: What Happened At the end of April, GNIRS was warmed up for routine cold head service. In the process of servicing the cold heads, the fast warm-up system and vacuum pumps were left on over the weekend; this has always been the normal operating procedure. The GNIRS fast warm-up system has been used on the order of a dozen times without incident. The system has a completely independent controller that shuts off power to the heater resistors when the temperature set point is reached. It is independent of all other Gemini and GNIRS software. For some unknown reason the controller failed, resulting in continuously heating GNIRS until it reached temperatures near 200° C for an undetermined period of time. The fast warm-up system did not have thermal fuses or circuit breakers. When Gemini staff arrived on Monday, they recognized there was a problem and shut the heaters off. They …

14 Mayo 2007: An Australian team, led by Sarah Brough of the Swinburne University of Technology used the Gemini South Telescope to find that the most massive galaxies evolve through a variety of mechanisms which are dependent on the mass of their cluster environment. These observations are not consistent with any single model of galaxy formation, presenting a challenge for theorists. Brightest cluster galaxies (BCGs) are the most massive galaxies known. They are generally red, elliptical type galaxies with remarkably similar brightnesses that are only found near the centers of galaxy clusters. To understand how galaxies form and evolve it is vitally important to understand the formation of these massive galaxies. The uniformity of BCGs suggests that they have experienced similar evolutionary histories and their position at the centers of clusters suggests that their histories must be connected to their environment. Current models of galaxy formation predict that the stars in these most …

18 Abril 2007: Analysis of nine short gamma-ray bursts (GRBs) observed with Gemini, Magellan, and the Hubble Space Telescope reveals that the progenitors of these GRBs may reside in faint host galaxies at redshifts of z = 1.1 and beyond (geminiann07004a). Unexpectedly, the host galaxies of these short GRBs (with R ~ 23-27 mag) can be more than a 100 times fainter than those of previously known short GRBs (brighter than R ~ 22 mag) (geminiann07004b). Therefore the hosts of the recently observed short GRBs are starkly different from the first few short GRBs hosts, which were all at z < 0.5. It seems that our understanding of the nature of GRB progenitors may be undergoing a paradigm shift. Although initial observations suggested that short GRBs occur at significantly lower redshifts than long GRBs (which occur at z ~ 3), the recent observations establish for the first time that a third or more …

2 Marzo 2007: Mapping Gas Jet Velocities in the Molecular Cloud W51 IRS2 A team led by John Lacy of the University of Texas at Austin recently used the instrument TEXES on Gemini North to map the star-forming region IRS2 located deep within the molecular cloud associated with the giant H II region W51. The spatial and spectral performance of TEXES on Gemini allowed the team to separate the ionized gas into several components for the first time. These include: an extended HII region on the front surface of the molecular cloud, several embedded compact HII regions, and a streamer of high velocity gas. The team interpreted the high velocity streamer to be a precessing or fan-like jet that has emerged from the molecular cloud into an OB star cluster where it is being ionized. The source of the jet is unknown. The presence of such a jet coming from within the molecular …

19 Enero 2007: Marie-Claire Hainaut, a member of the Gemini science staff, was observing with the Gemini South telescope in central Chile on the night of January 18th when she captured this image of Comet McNaught in the twilight sky. The recently arrived Comet McNaught has put on a world-wide show over the last two weeks during its apparition in the western sky. Surprising even veteran comet researchers, McNaught has become the brightest comet visible in over 40 years. The image taken by Marie-Claire shows the bright nucleus low in the sky over the town of Andacollo in the foothills of the central Andes. The sweeping dust tail of the comet can be seen extending over 30 degrees toward the zenith. When asked about the image Marie-Claire noted, “When I went outside from the telescope control room and looked to the west I was stunned… The comet and its amazingly large tail were …

19 Enero 2007: January 19, 2007 New mid-infrared images of the Zeta Leporis circumstellar disk obtained with T-ReCS on Gemini South have for the first time revealed what researchers are calling an "exo-asteroid belt" around another star. Far from a passive dust disk, the new data show that there must be some sort of ongoing collisional activity within a few astronomical units (AU) of the star. These collisions sustain the replenishment of the small dust grains detected in the T-ReCS images. The results also lend support to the theory that the Zeta Leporis system contains a large reservoir of asteroid-sized bodies as well as the possibility of rocky planets. The team, lead by University of Florida Ph.D. student Margaret Moerchen and her advisor Charles Telesco, observed Zeta Leporis as part of a broader research program centered on the search for resolved circumstellar disks. The Gemini observations supplement previous observations made in 2001 that …

19 Diciembre 2006: A new series of images are now available that provide a "wide-eyed" view of the Gemini North telescope. The images were obtained as part of a program to capture a time-lapse sequence of the Gemini telescopes in operation during the course of one night. Each image shows a complete 180-degree view illuminated by moonlight (except for exterior views). All images were obtained using a circular format fisheye lens and ~50 second exposures to simulate the naked-eye view of the telescope at night.

15 Diciembre 2006: A team of US astronomers led by Sebastian Daemgen (University of Arizona) has just released the results of a search for low-mass brown dwarf or planetary companions around young early-type M dwarf stars within 20 parsecs of the Sun. The 41 stars in the survey have age estimates of < 300 million years, comparable to that of the Pleiades. Within the sample 13 objects are found to host fairly bright companions, eight of these (seven binaries and one triplet) are new discoveries (Figure 1). Understanding binarity or multiplicity rates in low-mass stellar systems could provide important clues on the formation of low-mass objects including planetary systems and their population of planets. The survey was conducted using The Gemini North adaptive optics system ALTAIR in its natural guide star (NGS) mode. The strategy of the survey was to target young stars in order to increase the probability of finding intrinsically faint …

12 Diciembre 2006: A British team led by Matt Burleigh (University of Leicester) and P. F. L. Maxted (Keele University) have discovered and characterized an extremely rare stellar system composed of a white dwarf and brown dwarf pair. Named WD 0137-349, this pairing is the only known close, detached binary system with a white dwarf and a confirmed substellar companion. The system is exceptionally intriguing given the measured orbital period of P = 116 minutes. Such a short period implies that the stars orbit within one solar radius from one another. This is close enough that the brown dwarf must have survived the period of common envelope evolution where it was completely engulfed by the atmosphere of the red giant progenitor of the white dwarf. Earlier work by Maxted et al. had already established a mass of 0.39 +/- 0.035 Msun for the white dwarf and of 0.053 +/- 0.006 Msun for the …

13 Noviembre 2006:

31 Octubre 2006: Robert A. Simcoe of the MIT-Kavli Center for Astrophysics and Space Research has found new evidence of intensive heavy-element enrichment in intergalactic gas, occurring less than 1 billion years (Gyr) after the Big Bang. His discovery of a high concentration of carbon atoms in the spectra of two very distant quasars implies that vigorous star formation was already underway in some neighborhoods when the universe was only 7% of its present age. Charting the evolution of the carbon abundance is like taking a core sample of the early universe's stellar content. Since carbon nuclei are created through fusion in stellar cores, one would expect their abundance to decline at early times, approaching the formation epoch of the first stars. Simcoe's new observations show that the level of triply ionized carbon (i.e. carbon which has been stripped of three electrons, usually denoted as C IV) remains surprisingly constant as far as …

30 Octubre 2006: An international team of researchers used Gemini mid-infrared images to investigate a sample of nearby Luminous InfraRed Galaxies (LIRGs) which are analogous to those LIRGs which are major contributors to the obscured star formation rate (SFR) density at redshift z=1, when the universe was half of its present age. The data were obtained with the mid-infrared imager/spectrograph T-ReCS on Gemini South. In Figure 1 the diffraction-limited images reveal that at high-spatial resolution, approximately 0.3 arcsecond at the observed wavelengths of 8 and 10 microns, the morphology of the mid-infrared emission in the nuclear regions of these galaxies is strikingly similar to that of the ionized gas (Paschen-alpha) revealed by Hubble Space Telescope (HST) NICMOS observations at near-infrared wavelengths. The observed mid-infrared emission of these LIRGs generally consists of bright nuclear emission, multiple circumnuclear and/or extranuclear H II regions, and diffuse emission. The stellar emission, traced by the NICMOS near-infrared continuum …