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22 Octubre 2003: The Gemini Observatory recently reached an important milestone - successful coating of the secondary mirror on Gemini South with silver. Previously, with aluminum coatings on both primary and secondary mirrors, Gemini's combined emissivity was 3.8%. Reaching this new milestone, we are increasingly confident that achieving our ambitious goal of 2% total telescope emissivity is attainable. Reflectivity and emissivity are two measures of a mirror's performance. A highly reflective mirror is desirable in any optical telescope in order to maximize the amount of light reaching the science instrument. Ideally, a coating should reflect as close to 100% of the light that strikes it. In the thermal infrared region of the spectrum, however, a mirror coating emits a great deal of infrared radiation, and the statistical "noisiness" of this emission reduces an infrared instrument's sensitivity to emission from astronomical sources. The emissivity of an optical surface is defined as the ratio between …

2 Octubre 2003: Daniel Stern of the Jet Propulsion Laboratory and his USA-UK-Chile team of astronomers (including Gemini-South Astronomer Michael Ledlow) used the visiting instrument FLAMINGOS, a multi-object near infrared spectrograph at Gemini South to study the high redshift quasar SDSS J083643.85+005453.3 (SDSS J0836+0054). SDSS refers to the Sloan Digital Sky Survey, where the quasar was first discovered. The authors report their findings in "Gemini-South+FLAMINGOS Demonstration Science: Near-Infrared Spectroscopy of the z = 5.77 Quasar SDSS J083643.85+005453.3", The Astrophysical Journal Letters, 10 October 2003. Both CIV (at 1549 Angstroms) and CIII] (1909 Angstroms) were detected in the quasar at a redshift of z = 5.774 +/- 0.003 (See Figure 2). The new redshift derived from these lines is more accurate than the previous optical estimate (z=5.82), based on a single broad line, Lyman alpha (See Figure 1). Because of its high redshift and foreground absorption by our own galaxy, the quasar is invisible …

2 Septiembre 2003: The deflection of light by the deep gravitational potential of galaxy clusters can be harnessed to greatly increase the effective collecting area of astronomical telescopes. Mark Swinbank (Ph.D. student at the University of Durham, U.K.) and his international team used Gemini's Multi-Object Spectrograph with Integral Field Unit (GMOS-IFU) on The Frederick C. Gillett Gemini Telescope (Gemini North) to exploit the rich galaxy cluster A 2218. They used A 2218 as a magnifying glass to observe distant background galaxies at a comparable level of detail to galaxies at redshift z ~ 0.1. This work is part of Mark's Ph. D. project––to explore the Tully-Fisher relation and chemical abundance gradients in distant young galaxies. Swinbank et al., report on their first result of spatially-resolved [OII]3727 nebular gas emission from a lensed galaxy at a redshift z=1.034. This corresponds to an epoch half the present age of the universe. Using a detailed model …

19 Agosto 2003: PHOENIX was used to sample multiple stellar atmospheres and has revealed tantalizing clues that neutrino interaction during the supernovae explosion of massive stars is involved in the genesis of fluorine. PHOENIX uses a Gemini supplied 1024 x 1024 InSb Aladdin II array. Despite our awareness of fluorine's unique properties, its astrophysical origin is not well understood. Like most heavy elements, fluorine is a product of nuclear reactions in the hot cores of stars during various phases of their evolution. Furthermore, fluorine is not easy to observe in the universe, and very few spectroscopic measurements of fluorine in stars exist. Until the recent Gemini work reported here, only a meager set of data for a few stars in our own Milky Way was available. A spectroscopic program conducted at Gemini South, located on Cerro Pachón, Chile, has changed this picture. Katia Cunha (Observatório Nacional, Brazil) led a PHOENIX team of researchers …

6 Agosto 2003: High spatial resolution NIRI images taken in the 1.69-micron methane absorption band expose the detailed structure and varying chemistry of the clouds high in the Jovian atmosphere. The image of Jupiter was obtained as part of a systems check for the Gemini Near-Infrared Imager (NIRI) and was also used for a contest in which a Canadian elementary school student selected Jupiter as a target for Gemini. The Canadian Gemini Office located at the Herzberg Institute of Astrophysics in Victoria, BC, together with the Canadian Gemini Scientist sponsored a contest for Canadian school children. The aim was to make students more aware of astronomy in general and the Gemini Observatory in particular. Each entrant submitted a short paragraph on their favorite object in the sky and the winners were selected on the basis of the originality of the object and the reasons why it was their favorite celestial object. Two prizes …

23 Julio 2003: As a part of commissioning and engineering runs at the Frederick C. Gillett Gemini North Telescope in June and July 2003, the mid-infrared imager and spectrograph MICHELLE was used to image the young planetary nebula NGC 7027. Planetary nebula is the name given to the gas ejected from, and heated by, a low to intermediate mass star as the star makes the transition from red giant to white dwarf. As the radiation pressure from the contracting and heating core of the red giant causes the star to lose its outer atmospheric layers, the intense ultraviolet radiation from the core raises the temperature of those layers to tens of thousands of degrees Kelvin, causing the gas to glow. The planetary nebula phase of stellar evolution lasts only a few tens of thousands of years before the gas is so distant from the star that it no longer glows. NGC 7027 is …

17 Junio 2003: On the second night of its first commissioning run on the Gemini South Telescope, the facility mid-infrared imager/spectrograph T-ReCS was used to obtain an image of Mars using a spectral filter centered at a wavelength of 12.8 microns. The image was made at 7h27m UTC on 2003 June 4. Bright areas are relatively warm, and dark areas may be cooler. In the "raw" image on the left, the bright region corresponds to the sub-solar point; there is a brightness gradient roughly symmetrical about the sub-solar point, actually skewed a bit towards mid-afternoon due to thermal inertia. The middle image shows a specially processed (unsharp-mask) version of the T-ReCS data that accentuates finer details. The right image is a composite of visible data from the Mars Global Surveyor (National Geographic Society, MOLA Science Team, MSSS, JPL, NASA) taken from the Mars Now webpage and shows Mars at approximately the same orientation …

27 Mayo 2003: Issue #26 (June 2003) of the Gemini Newsletter has been printed and is now being shipped to all partner offices.

12 Mayo 2003: In 1943 the American astronomer Carl K. Seyfert reported that a small percentage of galaxies have very bright nuclei that are the source of broad optical emission lines seen in their spectra. Nearly stellar in appearance, these nuclei are responsible for the emission of strong lines produced by atoms in a wide range of ionization stages. Today these objects are known as Seyfert Galaxies and the spiral galaxy NGC 4151 is a good example of this type of object. Seyfert Galaxies belong to a broader class of objects called Active Galactic Nuclei (AGN) that are characterized by energetic emission across the entire electromagnetic spectrum, from the radio to X-rays. The power source for an AGN is thought to be a central supermassive black hole where energy is generated by matter accreting onto the black hole itself and onto its surrounding accretion disk. James Radomski of the University of Florida and …

29 Abril 2003: Some highly magnetized neutron stars (magnetars) are known to periodically flare up and emit large quantities of X-rays. These bursts are thought to be caused when the solid surface of the neutron star cracks, triggering "star quakes." The energy is transferred to the magnetic field and out into the hot gas that is trapped near the magnetar. One such X-ray burst was recently observed from a type of magnetar that had not been seen to burst before, conclusively linking two types of neutron stars that had previously been thought to be different. Gemini's Near-Infrared Imager, NIRI, was trained on the magnetar 1E 2259+586 shortly after X-ray bursts were detected in June of 2002. The magnetar was observed to be more than 3 times brighter in the infrared than it is in its quiescent phase. NIRI re-imaged the magnetar a week later and confirmed that it was fading, showing that the …

15 Abril 2003: Binary stars evolve in interesting ways. The more massive star in a pair evolves faster and may explode as a supernova if its original mass is greater than about 7 times the mass of our Sun. The result is that either a neutron star or a black hole is found orbiting the lower-mass companion star - as is the case with A0620-00. This system consists of an X-ray novae star, powered by the sporadic accretion material from its companion, a K5 main-sequence star. The relative faintness of the secondary star has allowed the measurement of the radial velocity of both the accretion disk around the black hole and the companion star. The black hole mass is still not well known; the most recent estimate is 11.0+/-1.9Msun (solar mass). 2668-2678, November 2001). A more robust measure is that the mass has to be greater than 2.72+/-0.06Msun. Soft X-ray transients (SXT), also …

2 Abril 2003: Saturn's moon Titan, the second largest moon in the solar system, is surrounded by a thick atmosphere of molecular nitrogen with a few percentage points of methane. This atmosphere appears to host a variety of meteorological features that show a seasonal cycle. Titan's apparent angular diameter from Earth (~0.8 arcseconds) can be resolved from the ground only with advanced techniques like adaptive optics. The opacity of Titan's stratospheric haze decreases sharply with wavelengths across the visible into the infrared. There are narrow spectral windows in the near infrared between the methane bands through which astronomers can probe Titan's surface and lower atmosphere. Henry Roe (University of California, Berkeley) and his collaborators used adaptive optics on the Gemini North and Keck II telescopes to study the tropospheric haze and the discrete clouds of Titan, and to probe its surface (Figure 1). Their observations have revealed that the southern hemisphere shows more …

25 Marzo 2003: Over 5 days in late February/early March, staff members completely moved into the new Gemini South Southern Base Facility in La Serena, Chile. The 15,000-plus-square-foot facility features 30 offices, a 42-seat lecture hall, 2 instrument labs, 2 conference rooms and the Gemini South sea-level control room. Approximately 40 staff members currently occupy the facility.

26 Febrero 2003: The Gemini Near-infrared Imager (NIRI) has been working reliably and delivering excellent images at wavelengths between 1 and 5 microns. In one NIRI program, very sharp images (0.35 arcsecs FWHM without adaptive optics correction) of 11 different sub-regions of the nearby spiral galaxy M33 were collected over a period of two nights in September 2002. The infrared NIRI images probe through the intervening dust in M33 and allow us a clear view of the many evolved giant stars in this galaxy. In the inset infrared (IR) image, 22,000 individual giant stars were detected and measured. The image on the left shows what this same field looks like at visible wavelengths with a seeing of 0.75 arcsecs (FWHM). The dust seen in the optical image all but disappears in the NIRI IR image (a composite of 1.6 and 2.1 micron images). Taking a census of the stars in other galaxies is …

12 Febrero 2003: The tightest orbiting brown dwarf companion ever seen has been discovered orbiting the low mass star LHS 2397a, using adaptive optics on Gemini North. The faint companion completes its orbit around the parent star at a distance of about 3 astronomical units (AUs) every 20 years. The images above show LHS 2397a in four bandpasses. The first image on the left is an optical image in the I Band obtained with the Hubble Space Telescope (HST) on April 12, 1997. The brown dwarf is seen as the very faint object at nine o'clock and is very difficult to detect in this unenhanced image. The next three images were obtained using adaptive optics in the near infrared (J, H and K' bands) on Gemini North five years later (February 7, 2002). The Gemini images use a Fourier filter to enhance the visibility of the companion, hence the presence of the companion …

28 Enero 2003: Today, in a live videoconference connecting Hawai`i with Chile, the six teachers selected to participate in the Gemini Observatory StarTeachers Exchange Program were officially announced. During the event, the 3 teachers from each location met and shared some of their ideas for the exchange using the same advanced high-speed internet videoconferencing technology that they will use to present lessons to their students back home during the exchange. The Hawai`i teachers are scheduled to visit their colleagues in Chile for two weeks in March and the Chilean teachers will make a reciprocal visit to Hawai`i in October 2003. The three Big Island StarTeachers selected are Kristen Luning, Chairperson of the Math Department at Keaau High School; Alicia Hui, a fifth grade teacher at Haili Christian School; and Christine Copes, a math and Resource Teacher at Waiakea Elementary School. The three Chilean teachers are Carmen Luz Briones, Viviana Calderon and Jenny Opazo. …

21 Enero 2003: Violent bush fires ravaging Canberra destroyed most of the facilities at the Stromlo Observatory. Fortunately there were no additional human injuries or casualties. More details on the loss of Gemini's Near-Infrared Integral Field Spectrograph can be found at the links below. Astronomy projects in ruins as observatory obliterated Aussie Fires Destroy Mount Stromlo Observatory Australian fire felt in Hilo Gemini Near-Infrared Integral-Field Spectrograph (NIFS): Destroyed by Bushfire January 2003 Historic Australian observatory gutted The Mount Stromlo Fires: A Major Heritage Loss For Australian Astronomy Mount Stromlo Observatory Destroyed by Fire Pictures of the aftermath of the fire of Saturday, 18 January 2003, at Mount Stromlo Observatory

9 Enero 2003: Gemini South Assistant Astronomer Dr. Michael Ledlow has helped confirm the existence of a giant, subatomic particle jet streaming from a spiral galaxy similar to the Milky Way. Though long known to be associated with elliptical and merging galaxies, the discovery of such jets streaming from a spiral galaxy raises significant questions about current theories on jet production. The discovery was made possible by the combination of radio, optical and infrared observations. The findings were reported at the American Astronomical Society's meeting in Seattle. Dr. Ledlow's infrared work at Gemini South was instrumental in complementing research by the team leader, Dr. William Keel with the University of Alabama, and Dr. Frazer Owen with the National Radio Astronomy Observatory. The galaxy, known as 0313-192, first came to the attention of Dr. Owen more than 20 years ago during a galaxy survey he conducted using the Very Large Array (VLA). Gemini South's …

18 Diciembre 2002: The Gemini Multi-Object Spectrograph (GMOS) at Gemini South Gemini South took delivery of GMOS-S in November 2002 and is preparing to install it on the telescope for commissioning very early in 2003. It is anticipated that GMOS-S will be available during semester 2003B in both imaging and several spectroscopic modes. Like its twin that began observations in 2001 on Gemini North, GMOS-S was built as a collaboration between Canada (HIA), and the UK (Astronomical Technology Centre at ROE and University of Durham). The GMOS detector system was provided by the US (National Optical Astronomy Observatory). The two GMOSs are the primary instruments for optical (0.36-1.10 µm) slit/multi-slit/integral field spectroscopy as well as imaging (5.5 arcmin field of view) on the Gemini telescopes. Michelle at Gemini North The facility mid-infrared imager and spectrometer Michelle arrived at Gemini North in the first week of December, however, Michelle did not arrive from the …

2 Diciembre 2002: The Large Magellanic Cloud, a small satellite galaxy at a distance of about 50,000 parsecs, is a prime target in which to probe the chemical evolution of stars. Because this galaxy has a different star formation history than our own galaxy, the properties of its stars are different. Variations in galaxy evolution can lead to differences in chemical composition, which result in stars that noticeably differ in the later phases of their evolution. Measuring and understanding these chemical differences help unravel the physics of the complexes processes of nuclear burning and mixing that take place in the red giant and later phases. Within a given stellar population in a galaxy, chemical evolution is driven primarily by stellar nucleosynthesis, with the dispersal of the processed material back into the galactic interstellar medium (ISM). This heavy-element enrichment over time depends on such processes as star formation history, internal stellar evolution and nucleosynthesis …