Announcement: Gemini Observatory

23 Febrero 2005: About 500 million years ago a spheroidal galaxy captured a small gas-rich galaxy in a merger that led to a burst of star formation. Using the integral field unit (IFU) on GMOS-South, Mark Swinbank (University of Durham, UK), led an international research team to explore this merging system that is still in the process of digesting the gas and stellar components of the two original galaxies. The galaxy SDSS J101345.39+011613.06, known simply as “E+A” (geminiann05002a), has a redshift of 0.1055, corresponding to a distance of roughly 490 Mpc (or 1.6 billion light-years). This hybrid galaxy has a disturbed morphology and shows signatures of both old low-mass stars (spectral type K) and massive but short-lived stars (spectral type A) distributed throughout. However, the youngest and most massive ones—the OB-type stars—are missing, which indicates that the last star-forming event in E+A took place a few hundred million years ago. Recent spectroscopy conducted …

27 Enero 2005: A long-standing problem in understanding the evolution of stars has been determining the nature of the stellar progenitors for white dwarf stars. In particular, astronomers want to know how a rather massive star (up to seven times the mass of the Sun) can lose enough mass to become a white dwarf. Key questions include: Which main-sequence stars eventually end their life as white dwarfs? How much mass do they lose in late evolutionary stages? What process allows this to occur? Some answers can be found in the 100th published paper based upon Gemini data. A Canadian, U.S., and Australian team led by Ph. D. student Jason Singh Kalirai of the University of British Columbia selected 24 individual white dwarfs[1] in the field of the rich open star cluster NGC 2099 (M37). This initial identification was made from analysis of deep wide-field imaging using the Canada-France-Hawaii Telescope. By following up on …

7 Diciembre 2004: Gemini staff have successfully repeated the coating of a 8-meter primary mirror with protected silver during a 9-day shutdown period. This is the second successful silver coating of a Gemini primary mirror and was applied on Thanksgiving Day in a 7-hour process interrupted by an intense hail storm at midday. This is the second time a Gemini primary mirror has been coated with protected silver (Gemini South was coated in May 2004) and now all key optical surfaces (primary, secondary and science fold mirrors) are coated. This is a milestone in front surface mirror coating technology. The result is a dramatic reduction in the thermal emissivity of the telescope systems—down to an unprecedented level of about 2% or lower. Following the successful coating, team members cheered as reflectivity values were announced and they realized that the coating was successful. The application of protected silver coatings on both Gemini telescopes is …

30 Noviembre 2004: Kevin Luhman (Harvard-Smithsonian Center for Astrophysics), Dawn Peterson (University of Rochester) and S. T. Megeath (also CfA) used the newly commissioned Gemini Near Infrared Spectrograph (GNIRS) on Gemini South to determine the nature of the low-mass object OTS 44. The observations of the faint infrared object confirmed that it is a very low-mass, newborn brown dwarf and the lowest mass brown dwarf found to date in the Chamaeleon I cloud complex. The Chamaeleon I cloud complex is a nearby star-forming region located about 170 parsecs (554 light-years) away from us toward the constellation of Chamaeleon. From the strength of the water vapor (steam) absorption band around 1.5 and 2 microns, and in comparison to other low-mass stellar objects, the team determined OTS 44 to be of very late spectral type M9.5 (geminiann04018a). They estimate its effective temperature at 2300 K. Using the flux in the H band and the object’s …

4 Noviembre 2004: Using archived science verification data from the Hokupa'a/QUIRC Adaptive Optics system on Gemini North, a French/US team of astronomers led by Jean-Pierre Maillard of the Institut d’Astrophysique de Paris has confirmed the physical association of a cluster of massive stars in the infrared source IRS 13 near the center of the Milky Way galaxy. The team also used data from Hubble Space Telescope, the Chandra X-Ray Observatory, the Canada-France-Hawai’i Telescope (CFHT), and the Very Large Array to complement the Gemini data. The Gemini observations consisted of deconvolved H and Kp band images that identified the existence of two formerly undetected sources within the eastern component of IRS 13 (called IRS 13E). When the Gemini data were used in conjunction with longer and shorter wavelength observations, it was possible to conclude that these sources were massive stars comparable to the stars of the same type which are exceptionally concentrated in the …

27 Octubre 2004: Closest Known Brown Dwarf has a Companion. While searching for planet-sized bodies that might accompany the nearby star system Epsilon Indi, astronomers using the Gemini South telescope in Chile made a related but unexpected detection. Widely observed by telescopes on the ground and in space, Epsilon Indi was known to host an orbiting companion, called Epsilon Indi B, which was discovered last year and is the nearest known specimen of a brown dwarf. Brown dwarfs are very small, cool stars thirty to forty times more massive than Jupiter but of similar size. Despite all the observing, it took the combination of Gemini's powerful infrared capabilities and the extremely sensitive spectrograph/imager called PHOENIX (without adaptive optics) to reveal the more elusive body. "Epsilon Indi Ba is the closest confirmed brown dwarf to our solar system," says Dr. Gordon Walker (University of British Columbia, Vancouver, Canada), who led the research team that …

19 Octubre 2004: Eight meter-class telescopes such as Gemini, the Very Large Telescope (VLT), Subaru and Keck have opened up the high-redshift universe for detailed study. Several galaxies out to redshifts of z ~ 6.6 are now known and Gemini has played a significant role in their discovery: "Searching for the end of the cosmic dark ages with GMOS", "Gemini Probes Galaxy Evolution a Billion Years After the Big Bang". Finding even more distant galaxies is particularly important to our understanding of the formation of the very first stellar objects in the history of the universe, and of the ensuing reionization of the intergalactic medium. This epoch of “first light” at redshifts between ~7-15 marked the end of the early universe’s dark ages – a time when the universe was filled with mostly neutral hydrogen. Recently, Pelló et al. (Astronomy and Astrophysics, vol. 416, p. 35, 2004) identified a possible highly magnified object …

9 Octubre 2004: A stunning image released today by the Gemini Observatory captures the graceful interactions of a galactic ballet, on a stage some 300 million light years away, that might better be described as a contortionist's dance. The galaxies, members of a famous troupe called Stephan's Quintet, are literally tearing each other apart. Their shapes are warped by gravitational interactions occurring over millions of years. Sweeping arches of gas and dust trace the interactions and possible ghost-like passage of the galaxies through one another. The ongoing dance deformed their structures while spawning a prolific fireworks display of star formation fueled by clouds of hydrogen gas that were shocked into clumps to form stellar nurseries. This unprecedented image of the cluster provides a unique combination of sensitivity, high resolution and field of view. "It doesn't take long to reach an incredible depth when you have an 8-meter mirror collecting light under excellent conditions," …

21 Septiembre 2004: After more than five years of planning and development, the Gemini Science Archive Version 1 (GSA V.1.0) was released on September 20, 2004. The concept of an astronomical science archive, where data from a telescope is stored safely for posterity, is not new. What makes the GSA unique is that it allows quick, easy and complete access to all aspects of the science data. This was the vision of the Gemini archive first proposed in the late-1990's by Fred Gillett and others. This updated version replaces a prototype that had been available since November 2003 and includes many new and improved features. Access to Gemini data through the GSA is unrestricted once users obtain a user account that can be obtained by completing a simple registration form. The GSA can be accessed via the CADC homepage at URL http://cadcwww.hia.nrc.ca or directly at http://cadcwww.hia.nrc.ca/gemini The first thing a user will notice …

17 Septiembre 2004: 2004 September 7, 2004 - Galactic Contortionists Captured by Gemini August 25, 2004 - MICHELLE and HIRES Observing Times are Traded August 11, 2004 - Searching for the end of the cosmic dark ages with GMOS July 21, 2004 - Gemini South Obtains First High-Resolution Image Of Supernova Dust July 9, 2004 - A high abundance of massive galaxies 3-6 billion years after the Big Bang June 30, 2004 - Gemini, Keck and Subaru Combine Efforts to Study the Assembly of a Large and Distant Galaxy Cluster June 9, 2004 - Gemini South is First 8-10 Meter Class Telescope With Protected Silver Coatings May 25, 2004 - Cosmic Powerhouses Dwell In Humble Homes May 18, 2004 - Gemini opens a new window into the era of galaxy assembly May 4, 2004 - Gemini Provides New Insights on the Origins of Jupiter and Saturn "Irregular" Satellites April 12, 2004 - Orphan …

25 Agosto 2004: Over the past few years, a more coordinated approach to the building and using of new instruments for very large telescopes has gained strong support among science policy makers and, increasingly, among scientists themselves. In this spirit, we are pleased to announce that Gemini and Keck have agreed to exchange five nights of observing time at each facility in semester 2005A. The Gemini user community will have access to five nights of HIRES, the optical high-resolution spectrograph on Keck I. In return, Keck users will have access to the mid-infrared imager/spectrograph MICHELLE on Gemini North for five nights. The nights will be "classically" scheduled. Gemini's MICHELLE is a mid-infrared (8-25 micron) imager and spectrometer. In its spectroscopic mode, MICHELLE allows observations with resolution of R = 200, 1000, 3000 and 20,000 at 10 and 20 microns. MICHELLE was recently re-commissioned on Gemini North after being on UKIRT for much of …

11 Agosto 2004: A team of U.S. astronomers led by James Rhoads from the Space Telescope Science Institute, reports the discovery of extremely high rates of star formation in one of the most distant known galaxies in the universe. LALA J142442.24+353400.2, named for the survey in which it was discovered and its celestial coordinates, lies at a redshift of 6.535, which puts it 12.8 billion light-years away and appearing as it looked some 850 million years after the Big Bang. This faint, distant galaxy is fabricating stars at a rate of more than 11 solar masses per year, a frenetic pace among galaxies at this distance and epoch in the early universe. Astronomers traced the galaxy’s starburst activity by measuring light emitted in the so-called Lyman-alpha emission line, using deep multi-object spectroscopy conducted at Gemini Observatory with GMOS-N and the Keck Observatory with the Deep Imaging Multi-object Spectrograph (Deimos). The galaxy was first …

21 Julio 2004: Infrared observations of Supernova 1987A made in October 2003 as part of the “checkout” of the new Thermal-Region Camera Spectrograph (T-ReCS) instrument on Gemini South have revealed dust emissions at a wavelength of 10 microns, corresponding to a temperature of about 150 degrees Kelvin. They are coming from a cool dust ring that is surprisingly luminous. It co-exists with hot gas components left over from the relic equatorial ring so prominently featured in images and data from other observatories in wavelengths from X-ray to radio. This T-ReCS observation is the first detection of mid-infrared emission from the ejecta ring of SN1987A in five years. The similarity of Gemini’s 10-micron image with those taken in X-ray images obtained by the Chandra Observatory, and at radio frequencies from the Australian National Telescope Facility, suggests that the thermal emission is due to the recent heating of pre-existing dust in the equatorial ring by …

7 Julio 2004: A Gemini team led by Karl Galzebrook of Johns Hopkins University has just released some spectacular results obtained from the Gemini Deep Deep Survey (GDDS) in the British journal Nature. The team found that at last two-thirds of massive galaxies appeared after the first 3 billion years following the Big Bang. However, a significant fraction of them are already in place in the early Universe. The GDDS was completed using the Gemini North telescope and the Gemini Multi-Object Spectrograph (GMOS-N). The team observed four widely-separated 30 arcmin2 fields. The spectroscopic exposure time for each field was about 30,000 seconds. The spectrograph was operated in the Nod & Shuffle mode. This technique enables the removal of contamination by the earth’s atmospheric luminescence to a high degree. Spectra of several hundred distant galaxies were obtained and measured. As has been suspected, massive, evolved galaxies are found at an epoch earlier than half …

30 Junio 2004: Large galaxy clusters represent the largest gravitationally stable assemblies of matter in the universe. Massive clusters of galaxies consist of thousands of galaxies and vast quantities of extremely hot intergalactic gas all held together by gravity. It is believed that clusters of galaxies grow in size and in number through time and we see many more galaxy clusters in the nearby (recent) universe than in the distant past. The assembly and growth of massive clusters involve complex interactions between dark matter, diffuse gas, and thousands of individual galaxies. The physical details of these interactions are currently not fully understood. Both computer simulations and theoretical work predict that the growth process of massive clusters is highly non-isotropic with the in-fall of matter and galaxy mergers occurring along preferred directions. The coalescence and funneling of matter should produce highly correlated structures in space, enhancing visibility in these preferred directions. This is referred …

18 Mayo 2004: May 18, 2004 Using a sophisticated technique called Nod & Shuffle, combined with the Gemini Multi-Object Spectrograph, ultra-deep spectra of several hundred distant, elusive galaxies were captured. These observations by the Frederick C. Gillett Gemini North Telescope help to paint a new picture of the nature and evolution of galaxies some 7 - 10 billion years ago. Multiple recent discoveries of galaxies at very high redshifts have opened a fascinating window into what happened less than a billion year after the Big Bang. However, there is a more recent time interval in the past history of the universe that has remained relatively unexplored until very recently. The so-called "redshift desert" corresponds to an era when the universe was between one-third and one-half its present age (between redshifts 1 < z <2). Relatively little is known of the galaxies in this period due to a combination of intrinsically faint galaxy spectra …

4 Mayo 2004: Gemini North Near Infrared Imager (NIRI) observations have confirmed that many of the "irregular" satellites around Jupiter and Saturn share a common ancestry. All the known planets of the solar system have moons, except for Mercury and Venus. Out in the realm of the gas giants large numbers of little worlds swarm around Jupiter, Saturn, Uranus, and Neptune. The "regular" satellites (often the largest and brightest) go around their planets in a prograde direction (the same direction as all the planet orbits around the Sun). They probably formed in planetocentric disks with nearly circular prograde orbits close to the equatorial plane of their planets. But the gas giants also have a surprisingly large retinue of "irregular" satellites (smaller and fainter) on highly inclined and eccentric orbits, both prograde and retrograde. Their "chaotic" orbits suggest that these small worlds formed outside circumplanetary disks and were captured by gravitational influences. Irregular satellites …

27 Abril 2004: The new GNIRS Integral Field Unit (IFU) arrived on Cerro Pachón (Gemini South) in February in a deceptively small package. The new IFU is about the size of a large paperback, but contains some 66 miniature optical elements. Designed and built by the University of Durham (UK), the IFU fits in the GNIRS slit slide mechanism, providing an alternative input "aperture" to the variety of traditional slit masks that feed the long-slit and cross-dispersed configurations of the instrument. With the IFU in the optical path, a 2-dimensional input field of roughly 3” x 5” is divided into 21 slices of 0.15” x 4.9” each. Then these are arranged end-to-end to form a pseudo-slit that is dispersed by one of the spectrograph's three gratings as if it was a normal long-slit. This gives GNIRS the ability to form spectra of each 0.15” x 0.15” sample over the entire field without gaps. …

12 Abril 2004: A team of Brazilian and French astronomers led by C. Mendes de Oliveira has discovered four surprisingly metal-rich HII regions and associated clusters of hot young stars in an otherwise empty region of intergalactic space near the galaxy group called Stephan's Quintet. This collection of interacting galaxies (which lies about 280 million light-years away from us) is spreading clouds of gas and newborn stars across space. The newly discovered HII regions lie more than 80,000 light-years away from the center of action. Their relative youth and lack of apparent connection to the star-forming regions in the nearby quintet of galaxies raise questions about the sequence of events leading to their formation. A team of Brazilian and French astronomers led by C. Mendes de Oliveira has discovered four surprisingly metal-rich HII regions and associated clusters of hot young stars in an otherwise empty region of intergalactic space near the galaxy group …

8 Marzo 2004: The GLARE (Gemini Lyman Alpha at Reionisation Era) team, an international group of astronomers using Gemini to study the early universe, has just discovered a surprisingly large number (three) very high redshift galaxies ( z = 5.83, 5.79 and 5.94) in a same region of the southern GOODS field. Two of the Lyman alpha emitters measured are the faintest of any previous spectroscopic study. The objects are red (i' - z') > 1.3 and the faintest one has a z' magnitude of 27.15. This finding suggests the existence of large-scale structure at this redshift. This field is very close to the Hubble Ultra-Deep Field (UDF), a small portion of sky in the southern hemisphere recently imaged by the Hubble Space Telescope. The UDF is the deepest imaging ever done of a region in the sky. The completed survey and the images are being released by the Space Telescope Science Institute. …