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3 January 2006: Galaxy Clusters Galaxies frequently appear in large numbers as physical units bound by gravity. The largest are the galaxy clusters with hundreds of members, and at the smaller end are the compact groups of galaxies with a maximum of about 10 members. Between these are the “fossil groups” with members numbering in the dozens. A fossil group of galaxies is a system with a large extended x-ray halo, dominated by one very luminous elliptical galaxy that is surrounded by low-luminosity companions. Claudia L. Mendes de Oliveira (Universidade de Sao Paulo, Brazil) and her collaborators used GMOS, the optical imager/multi-object spectrograph on the Gemini North Telescope, to determine the first luminosity function (LF) of the galaxies in a fossil group based on spectroscopy of the member galaxies. The team observed the fossil group RX J1552.2+2013, and measured a mean redshift of z = 0.136 for 36 of its confirmed members. The …

12 December 2005: NGC 1068 The Closest Active Galactic Nucleus NGC 1068 is located about 14.4 megaparsecs away, making it the closest and best-studied example of an active galactic nucleus (AGN). An AGN emits copious amounts of energy from its nucleus, from very energetic x-rays to long wavelength radio waves. In addition to the intense radiation field, the nucleus of NGC 1068 contains a large amount of highly ionized and fast moving gas. In fact, some of the gas has been measured moving at up to several thousand kilometers per second. The accepted view is that the high-energy photons and high speed of the gases are generated in the vicinity of a massive black hole at the very center of the galaxy which is thought to have a mass of several million times that of the Sun. Studying the properties of gas and hot dust in such environment is a powerful approach to …

22 November 2005: The instrument clusters located at the Cassegrain foci of the Gemini telescopes are perhaps the most unique collections of astronomical instrumentation ever assembled on ground-based telescopes. Each cluster contains as many as four specialized instruments, each of which observes in a particular wavelength regime. When fully populated, both Gemini North and South can observe from the optical, through the near-infrared, and into the mid-infrared, covering a wavelength range from 0.4 to 25 microns. The Gemini South complement of instruments contains the optical imager and multi-object spectrograph GMOS, the mid-infrared imager/spectrograph T-ReCS, the near-infrared spectrograph GNIRS, and the high resolution spectrograph Phoenix. In addition, the optical high-resolution spectrograph bHROS is located in the pier of the telescope and is fed by a fiber link from GMOS. At Gemini North, the optical imager and multi-object spectrograph GMOS, the mid-infrared imager/spectrograph MICHELLE, the near-infrared imager/spectrograph NIRI, and the "point-and-shoot" adaptive optics system ALTAIR …

21 November 2005: International team of North American and European scientists has just published the first set of spectra of high- redshift supernovae based on the Supernova Legacy Survey (SNLS) conducted with MegaPrime/MegaCam at the Canada-France-Hawaii Telescope. The results impact our understanding of dark energy, and have appeared in two scientific papers led by D.A. Howell (University of Toronto) and another by P. Astier (LPNHU, Centre National de la Recherche Scientifique (CNRS) and Universitis Paris VI & VII). A large fraction of the supernova spectra have been obtained with the Gemini telescopes. SNLS uses Type Ia supernovae as standard candles to study the acceleration of the universe. Programs are underway at Gemini and other large telescopes to characterize the dark energy driving this expansion by measuring its average equation of state, w = p/ρ. Dark energy is a new, unaccounted-for form of energy that opposes the self-attraction of matter (due to gravity) and …

28 October 2005: The recent addition of a field lens in the Altair adaptive optics system has resulted in a significant improvement in near-infrared imaging capabilities at Gemini North. Altair with the field lens will begin regular science use in semester 2006A. Adaptive Optics - Straightening Bent Starlight Adaptive optics (AO) technology uses deformable mirrors to remove distortions to starlight caused by turbulence in Earth's atmosphere. Using this technology, astronomers can improve near-infrared images to rival the resolution of space-based observations. The technology is rapidly evolving and technologies such as laser guide stars and 3-dimensional turbulence mapping (multi-conjugate AO) are making the technology even more powerful. The lens was installed based on recent turbulence monitoring that demonstrated that about 60% of the turbulence on Mauna Kea occurs close to the ground. Altair was originally designed based on the assumption of a dominant turbulence layer at 6.5 kilometers. According to Gemini’s Associate Project Scientist …

5 October 2005: Based on Press Release from the University of Hawaii, Institute for Astronomy Astronomers using the Frederick C. Gillett Gemini Telescope on Mauna Kea have found the source of short flashes of gamma rays from outer space: a collision of two dead stars. For 35 years, astronomers have been fascinated by mysterious flashes of high-energy radiation from apparently random places in the sky. These events, known as gamma-ray bursts, were first discovered by U.S. military satellites designed to monitor nuclear tests in space. A typical burst lasts less than a few seconds, which makes them notoriously difficult to catch. In fact, until recently astronomers had been uncertain whether the bursts were coming from the solar system, the Milky Way, or distant galaxies. Because of this, research on the short bursts floundered for decades. However on July 9, 2005, Paul Price of the University of Hawaii Institute for Astronomy and Kathy Roth …

20 September 2005: With system and science verification complete, the Gemini Bench-mounted High-Resolution Spectrograph (bHROS) is available for science programs in 2006A. Proposals are due September 30, 2005. BHROS: a new and unique high-resolution optical spectrograph on Gemini South is the highest resolution optical (400-1000 nm) echelle spectrograph optimized for use on an 8-meter telescope. It achieves efficiencies of 13-18% (depending upon fiber mode with median seeing), with well-sampled spectra at a spectral resolution of R=150,000. Located within the thermally stable pier of the Gemini South telescope, bHROS is fiber-fed through the core of the telescope from the cassegrain focus. It is anticipated that bHROS will be well-suited for studies that include: High precision abundance analysis including determination of the 6Li/7Li isotopic ratio, abundances in ultra metal-poor stars, ISM, etc. Analysis of absorption line profiles High-precision radial velocity measurements (planet searches etc.)

7 July 2005: The Gemini community has embarked on a broad, multi-faceted search for planets around other stars. The prospect of answering the age-old question of how common solar systems like our own are in the universe captured the imaginations of astronomers who attended the June 2003 Aspen meeting, where new capabilities for the Gemini telescopes were imagined. In preparation for the next generation of planet-finding instruments, Gemini Observatory is actively looking for sub-stellar mass companions using the existing Adaptive Optics (AO) system Altair on Gemini North, and building the specialized near-infrared coronagraph (NICI) with its own AO system for Gemini South. Proposing for the NICI Planet Search Campaign We request that astronomers interested in participating in the NICI Planet Search Campaign send a short letter of interest to Joe Jensen, including the following details: name and institution; names and affiliations of other possible team members with whom you plan to or would …

2 July 2005: The Gemini North telescope on Mauna Kea successfully captured the dramatic fireworks display produced by the collision of NASA's Deep Impact probe with Comet 9P/Tempel 1. Researchers in two control rooms on Hawaii’s Big Island (on Mauna Kea and in Hilo) were able to keep enough composure amid an almost giddy excitement to perform a preliminary analysis of the data. They concluded from the mid-infrared spectroscopic observations that there was strong evidence for silicates or rocky material exposed by the impact. Little doubt remains that the unprecedented quality of the Gemini data will keep astronomers busy for years. “The properties of the mid-infrared light were completely transformed after impact,” said David Harker of the University of San Diego, co-investigator for the research team. “In addition to brightening by a factor of about 4, the characteristics of the mid-infrared light was like a chameleon and within five minutes of the collision …

28 June 2005: Imaging by Gemini North's Michelle mid-infrared imager/spectrograph has allowed an international team of researchers to isolate and characterize the dusty remains of the supernova remnant SN 2002hh some 20 million light-years away. Led by UK astronomer Michael Barlow (University College London), the team imaged SN 2002hh in the relatively nearby galaxy NGC 6946 to study the dust expelled (and/or created) during the supernova explosion. Earlier Spitzer Space Telescope observations identified the dust excess from the supernova as part of the Survey for Evolution of Emission from Dust in Supernovae (SEEDS) project using Spitzer Infrared Nearby Galaxy Survey (SINGS) Legacy data set. However, due to a lack of spatial resolution, these observations failed to confirm the identity of Source 1 (see Figure 1) as the supernova. The new Gemini results provided an approximately ten-fold increase in resolution at 11.2 and 18.5 microns and were able to clearly isolate the supernova source …

15 June 2005: It's Tough Being Small(At Least in the Trapezium Region...) The observed distribution of stars as a function of mass has a well-established behavior known as the initial mass function (IMF). For normal stars the IMF says that the quantity of more massive stars is lower than the number of less massive counterparts. In other words, smaller stars are more numerous than bigger ones. How does the IMF behave at lower masses, e.g. subsolar masses or for brown dwarfs, or even planetary size bodies? Stars in the Orion Trapezium region are bombarded by intense ultraviolet radiation. Does such a hostile environment influence the IMF? We do not yet know the answers to these questions. To help provide answers, Gemini South Flamingos-I observations of the outer Trapezium region by Lucas et al. have probed the region to very faint levels in the infrared. These observations provide partial but very instructive clues. Lucas …

1 June 2005: Dust Growth and Planet Formation Silicates found in the general interstellar medium or molecular clouds are exclusively amorphous, non-crystalline dust grains. However, both amorphous and crystalline dust grains are observed in more evolved stellar and planetary systems including those that, while still young, are in their later stages of formation. Thus, crystalline dust is present near T Tauri and Herbig Ae/Be stars, which are only a million or so years old, debris disks such as Beta Pic, which is 15-20 million years old, and our solar system, which is billions of years old (e.g., Comet C/1996 Q1). During the early formation and evolution of the dust in these systems, crystalline silicates form by a process that is still a mystery. The earlier we can look into the process of stellar evolution the better we can understand how the dust surrounding a young star is processed. Spectroscopy in the mid-infrared provides …

28 April 2005: A joint Chile-United Kingdom team led by Simon Casassus (University of Chile) has used the NOAO-built Phoenix near-infrared spectrometer on Gemini South to obtain high-resolution spectra (R~75,000) of the [Al VI] 3.66-micron line region in the planetary nebula NGC 6302 (the Bug Nebula). By modeling the multi-component structure of the line, the team has been able to derive values for the electric quadrupole constant in the [Al VI] transition and measure a reliable isotopic ratio for aluminum. This is the first time such a constant in an atomic transition has been measured in any astrophysical object. The isotopic ratio of Aluminum (Al-26/Al-27) is of astrophysical interest because it is a signpost of recent nucleosynthesis. Al-27 is the stable isotope, while Al-26 is radioactive – with a half-life of 720,000 years. Because the ratio is poorly established, the origin of Al-26 is currently assigned to a range of astrophysical processes ranging …

12 April 2005: Recent spectroscopic studies of infrared light reflected from the surface of Sedna reveal that it is probably unlike Pluto and Charon since Sedna's surface does not display evidence for a large amount of either water or methane ice. Due to Sedna’s extreme distance from the Sun, the frigid surface has probably been untouched for millions of years by anything except cosmic rays and solar ultraviolet radiation. Gemini Observatory astronomer Chad Trujillo led an effort by the same California Institute of Technology research team responsible for Sedna's original discovery to obtain spectra of this distant planetoid using the Near Infrared Imager (NIRI) on Gemini North. Their aim was to better understand the surface of this distant world and how it has evolved since its formation. “It is likely that Sedna has experienced an extremely isolated life in the outskirts of our solar system,” said Trujillo. “Out there beyond what we used …

28 March 2005: Can galaxies observed at very high redshifts (at a time when the universe was a fraction of its current age) evolve to look like today's nearby galaxies simply by growing older? The answer is no according to an international team of scientists led by Inger Jørgenson (Gemini Observatory) who used GMOS on Gemini North, combined with HST imaging data to survey distant galaxies and chart their evolution. The team's results demonstrate that cluster galaxies closer to us are not aged versions of the kinds of early galaxies seen in distant clusters that existed when the universe was half its current age, about seven billion years ago. To evolve into galaxies like those we see in nearby clusters, these galaxies require more than just a single episode of star formation as current theories suggest — the distant early "progenitors" have to undergo a set of profound transformations that most likely include …

11 March 2005: How do massive stars form? The time scale for massive star formation is much shorter than for low-mass stars. During the birth process, a massive core will form first and begin evolving (converting hydrogen to helium) while the larger protostar is still accreting material. Like their lower-mass cousins, massive stellar objects are obscured by overlying envelopes of gas and dust during their formation which makes this stage of massive star formation a challenge to observe. Despite the difficulty of discerning the massive cores as they form, progress is being made on both theoretical and observational fronts. New, large-aperture ground-based telescopes (like Gemini) are providing capabilities which allow astronomers to look much farther away to study more of these rare massive stars in their formative stages and evolve in their birth environments. An international team including Robert Blum (CTIO), Peter Conti (JILA), Augusto Damineli, Elysandra Figuerêdo, and Cássio Barbosa (University of …

23 February 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 January 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 December 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 November 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 …