National Optical Astronomy Observatories National Optical Astronomy Observatories Quarterly Report October - December 1989 National Optical Astronomy Observatories Quarterly Report October - December 1989 TABLE OF CONTENTS I. INTRODUCTION 1 II. SCIENTIFIC HIGHLIGHTS 2 A. The Brightest Hydrogen Emission Region in the Small Magellanic Qoud . 2 B. Measurements of Stratospheric Hydrogen-Fluoride (HF) 2 C. Rotation of Solar Active Regions 3 D. Reduction of the South Pole Data 3 E. The Effect of Large-Scale Flows on Oscillation Ring Diagrams 3 F. The Kinematics of Very Low Mass Galaxies: Is Dark Matter Ubiquitous? . 4 G. Outflows in YSOs: Dynamics Revealed by New Technology 4 III. PERSONNEL 6 A. Visiting Scientists 6 IV. INSTRUMENTATION, NEW PROJECTS AND OBSERVATORY ACTIVITIES 7 A. Future Telescope Technology Program (FTT) 7 B. Global Oscillation Network Group (GONG) 7 C. Instrumentation Projects 9 D. Observatory Activities 13 V. PROGRAM SUPPORT 15 A. Director's Office 15 B. 8-M Office 18 C. Central Administrative Services 18 D. Central Computer Services 18 E. Central Facilities Operations 19 F. Engineering and Technical Services 20 G. Publications and Information Resources 20 Appendices Appendix A Telescope Usage Statistics Appendix B Observational Programs Appendix C Annual Safety Report I. INTRODUCTION This quarterly report covers scientific highlights for the period of October - December 1989, as well as personnel changes for the period. Highlights emphasize concluded projects rather than work, in progress. The report also discusses new technology for telescopes and instrumentation, GONG, instrumentation projects, and observatory activities. The Engineering and Technical Services division now submits reports for the instrumentation projects, with contributions from program scientists, if necessary. The Associate Directors for CTIO and NSO continue to provide the information of efforts at La Serena/Cerro Tololo and Sacramento Peak. Activities of the NOAO units are included, and the appendices list telescope usage statistics, observational programs, and the NOAO annual safety report. H. SCIENTIFIC HIGHLIGHTS A. The Brightest Hydrogen Emission Region in the Small Magellanic Cloud. The most prominent and strikingly beautiful feature of the Small Magellanic Cloud is a large, bright (H II) region of hydrogen emission, designated as NGC 346, found in the northern part of this nearby galaxy. The source of ionizing radiation has long been suspected to be luminous stars with extremely high photospheric temperatures. In 1978 CTIO staff astronomer N.R. Walbom found, with the CTIO 4-m telescope, two such stars near the center of NGC 346. One of the stars, designated as NGC 346-1, was so hot and luminous (spectral type 04 III) that it was spectroscopically similar to Zeta Puppis, which is suspected to be one of the most luminous galactic stars known. However, as Walbom recognized, NGC 346-1 by itself could not produce the required ionizing radiation. This star was, however, part of a cluster of luminous stars. Indeed Walbom, who by 1986 had become a staff member at the Space Telescope Science Inst, and his collaborator J.C. Blades (European Space Agency) found, with the Anglo-Australian 3.9-m telescope, another extraordinarily luminous star in that cluster. Designated as NGC 346-3, the contribution of this new star (of spectral type 03 III) appeared to be comparable to that of NGC 346-1, but Walbom and Blades concluded that an assessment of their role in the total required ionization had to await further studies. Recently, P. Massey (KPNO), collaborating with J.W. Parker and CD. Garmany (U. of Colorado), reobserved at CTIO the central cluster in NGC 346. Photometry with the 0.9-m telescope and spectroscopy with the 4-m telescope of 42 cluster members identified 33 hot, luminous (0 type) stars, doubling the total number of such stars previously known in the Small Magellanic Cloud. The total ionizing flux of all the hot stars now known to exist within NGC 346 is consistent with the brightness of the hydrogen H n emission regioa Furthermore, and astrophysically more interesting, is the fact that the cluster contains very young bright stars estimated to fall in the mass range 40 to 85 solar masses~at the upper known limit of stellar masses. Thus this group of stars shows how extremely massive stars may be distributed in a star forming region and confirms their existence in significant numbers in the Small Magellanic Cloud. In addition, there is a group of somewhat older less massive stars; five of them are probably red supergiants and two are blue supergiants with masses estimated at about 15 solar masses. The presence of the evolved stars together with the more massive stars is not only an example of how massive stars evolve, but is evidence that one can not always assume, as is usually taken for granted, that all members of a star cluster field are coeval. B. Measurements of Stratospheric Hydrogen-Fluoride (HF). The molecule hydrogen-fluoride is one of several end products from a series of chemical reactions originating from the industrial release of fluorocarbons. Not found near ground level nor in the troposphere, HF appears confined to the stratosphere. Its presence is therefore not measured by normal gas sampling schemes. Thanks to a suggestion of C. Rinsland (NASA/Langley), L. Wallace (KPNO) and W. Livingston (NSO/T) have measured the strength of the HF feature at 24752.05 A in the 'Stokes' archives 1979-1985. HF is found to have doubled in strength over this time interval. New FTS data show the trend continues. The eruption of Mt. Redoubt in Alaska may also cause new increases of HF. Jet streams in December brought volcanic ash to Arizona for a short time. NSO is presently attempting to monitor HF using the 13.5-m vertical spectrograph. C. Rotation of Solar Active Regions. R. Howard (NSO/T) has examined the rotation of solar active regions using data from Mt. Wilson. He finds generally good agreement with some previous studies of plage and active region rotation characteristics, although the rates are slightly slower than those found previously for magnetic fields and faculae. Reversed polarity regions show little if any differential rotation, and the scatter in their rotation rates is larger than for regions showing normal polarity orientation. Larger regions rotate more slowly than smaller regions. There is a correlation of rotation rate with activity cycle phase that is similar in nature to that found in sunspot data. Leading and following portions of regions show very similar rotation rates, unlike spot groups, where the leading portions rotate more rapidly than the following portions. Active regions with polarity orientations nearest the normal orientation tend to show rotation rates nearest the mean values. In general these results support the notion that older, weaker magnetic fields at the solar surface have evolved different subsurface connections from the time that they were a part of sunspots or plages. It seems possible that they are connected at a shallower layer than are sunspot or plage fields. D. Reduction of the South Pole Data. S. Jefferies (Bartol/NSO/T) has continued work on the analysis of the 1981 and 1987 South Pole data sets. To address the issue of possible temporal variations in the mode frequencies due to changing solar activity, the differences in the mode frequencies from the two data sets (taken at times of high and low solar activity respectively), were computed for the frequency range 2.4 < v < 4.8 mHz and the degree range 3 < / < 98. It was found that the differences appeared to be independent of v and / over these ranges, with a mean difference (v„81 - v19g7) of 224 ± 19 nHz. This result is consistent with reports of increasing frequency with increasing solar activity. The line width measurements from the two data sets showed the same variation with frequency as that previously reported by K. Libbrecht (Big Bear Solar Obs.), an increase with degree (/) and with solar activity. Investigations are continuing into the line width measurements and their apparent variation with solar cycle. The 1987 data set was also used to make measurements of the rotational splittings of the sectoral modes (m = ± I) in the range (3 < / < 15). The measurements showed no indication of a dependence on the depth of the lower turning points of the modes. E. The Effect of Large-Scale Flows on Oscillation Ring Diagrams. F. Hill (NSO/T) has continued his development of the oscillation ring diagrams as a tool for mapping convection zone flows by theoretically computing the effects of large-scale flows on the ring diagrams. To do this, Hill has analyzed the forward problem, wherein a large-scale velocity field as a function of depth is assumed, the corresponding depth-weighted velocity for a given ring is computed, a dispersion relation is assumed, a set of artificial rings is generated, the artificial rings are fitted with ellipses, and the artificial ellipse parameters are compared with those obtained from the data. The computed results are sensitive to the choice of parameters in the assumed dispersion relation, and point out the need for more accurate determinations of these quantities. The chosen parameters minimize the rms deviation between the calculated ellipses using the velocity curves actually determined from the data, and the observed ellipses. These same dispersion relation parameters were then used to investigate the effect of different velocity curves on the rings. It was found that velocity curves with a local maximum were much better fits to the data than curves that varied monotonically. This is consistent with the velocity curve actually inferred from the data. F. The Kinematics of Very Low Mass Galaxies: Is Dark Matter Ubiquitous? Over a decade ago, work by V. Rubin (Dept. of Terrestrial Magnetism) and others on the rotation curves of spiral galaxies began to provide definite evidence for some amounts of non luminous matter in large spiral galaxies.