Announcement: Gemini Observatory

25 Febrero 2004: A Canadian/Gemini team led by Tim Davidge (Herzberg Institute of Astrophysics) used the ALTAIR adaptive optics system with the Near Infrared Imager (NIRI) on the Frederick C. Gillett Gemini North Telescope to probe the red stellar content in the starburst galaxy M-82. The field studied is at a projected distance of 1 kiloparsec above the disk plane of the galaxy. This amorphous, nearly edge-on galaxy is the third brightest member of a nearby collection of galaxies called the M-81 group which is located about 12 million light-years from our Galaxy. The interactions of galaxies in the M-81 group spur bursts of star formation in its members and M-82 appears to now be experiencing such a violent outburst. This activity in the disk of M-82 appears to drive a bipolar galactic wind that feeds gas to the outer regions of the galaxy. This work indicates that recent star formation in M-82 …

2 Diciembre 2003: Verne Smith of the University of Texas El Paso led an international team of American, Canadian, Brazilian and Japanese astronomers to a detailed study of the physical properties of the recently discovered nearby brown dwarf companion to Epsilon Indi, the fifth brightest star of the southern hemisphere constellation Indus. This T-dwarf star was discovered at Gemini South by Kevin Volk et al (2003) to be a close optical double consisting of an early T dwarf (Epsilon Indi Ba) and a late T dwarf (Epsilon Indi Bb) separated by 0.6 arcsec - see previous announcement, "Gemini Detects Something "Cool" in Our Neighborhood". With an accurately known distance of 3.626 +/- 0.009 pc, Epsilon Indi Ba and Bb are the nearest known brown dwarfs. High-resolution infrared (IR) spectra were obtained on Epsilon Indi Ba using the Gemini South Telescope and the NOAO PHOENIX spectrometer. The properties of Epsilon Indi Ba were explored …

19 Noviembre 2003: The prototype of the Gemini Science Archive (GSAp), shown in the picture below, was recently released to the astronomical community and the general public. This is a significant event in Gemini's maturation since it adds an end-point to the development sequence of high-level software systems. Now a Gemini user can seamlessly move from the application process via the Phase I Tool (the PIT), to observation definition using the Observing Tool (the OT), to observation execution using the Observatory Control System (the OCS), through data handling and storage (via the DHS), and finally into a permanent data archive (via the GSA). The release of the GSAp is an auspicious event and marks the first availability of Gemini science data to not just a project's principal investigator (PI) but to anyone who wants to make use of it. Many ground-based observatories and all space-based telescopes have previously developed data archives (for example, …

4 Noviembre 2003: November 4, 2003 A group of astronomers has recently studied the chemical make-up of distant galaxies in the "redshift desert," which is a virtually unexplored region of space between eight billion and ten billion light years away. Because the light from these galaxies moves at a finite speed, the galaxies are being seen when the Universe was between 20% and 40% of its present age. Studying the properties of galaxies at this particular time is important because it corresponds to a special age in the history of the Universe - a time during which it is thought to have made most of its stars. These observations were undertaken using the Gemini North telescope and a uniquely capable instrument, the Gemini Multi-Object Spectrograph (GMOS), which is able to target extraordinarily faint galaxies using a newly developed technique known as "nod and shuffle." This work is reported in "The Gemini Deep Deep …

29 Octubre 2003: ...Is a message that the StarTeachers successfully delivered to thousands of students in Chile and Hawai`i. The second-half of the inspiring StarTeachers program began on Saturday, October 11, in Waikoloa, Hawai`i, with a welcoming gala. During the gala, Gemini was honored to receive the Gabriela Mistral Medal for excellence in education from the Chilean Ministry of Education. The gala event kicked-off two weeks of teaching and cultural exchange. The StarTeachers have been busy on the Big Island. More images are provided in the StarTeacher's Photo Album. Additional information about the individual teachers and background information on the StarTeachers program is also available at our website. The StarTeachers spent most of their time in schools and classrooms in East Hawaii infusing students and other educators with their love of science, astronomy and culture. They visited 9 schools total with focused efforts at the Hawaiian StarTeachers' home schools - Keaau High School, …

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 …