K. Michael Merrill

Tucson Nighttime Scientific Staff


Areas of Interest

Star Formation, Young Stellar Objects, Interstellar Medium, Circumstellar Envelopes, Late Stellar Evolution, Infrared Instrumentation, Data Acquisition and Reduction

Recent Research Results

Merrill and Gatley have recently discovered a striking correlation between the results of two very different approaches to the study of the ionized gas in the Galactic center. Specifically, the dynamical model by Lacy et al. 1991 (ApJ 380, L71), based on observations of the neon 12.8 micron line, isolates a one-armed Keplerian spiral structure that is also prominent in Merrill and Gatley's images of the reddening of the ionized gas, based on KPNO 1.3 meter COB Brackett alpha and gamma emission line images. They will deploy capabilities unique to KPNO to study the "central engine" buried within the Galactic center, which is otherwise hidden from conventional optical techniques by massive extinction. Observations at both high angular resolution to get spatial details (provided by the DLIRIM real-time shift and add facility which produces diffraction-limited images at the 4 meter telescope) and high spectral resolution to get the kinematics (provided by the Phoenix spectrograph) will be required to scry the truth from the tangle in the Galactic center. These observations (currently scheduled for June, 1997) will significantly improve the database for ionized gas kinematics and star counts, providing a stringent test for the "central engine". Furthermore, because the Lacy spiral shows up as a distinct feature at a characteristic value in the extinction map one can confidently predict that the kinematic profiles at Brackett alpha and Brackett gamma will show differential extinction which will make it possible to tie the kinematic and the imaging experiments together.

Future Research Plans

The cosmic interface between "stellar systems engineering" and "practical astrophysics", which conspire to produce a continual supply of new stars, has has been the object of continued fascination to astronomers for many decades with each new discovery somehow whetting the appetite for more. Following the SQIID upgrade, Merrill will resume his pioneering study of regions of active star formation which has awaited extension to a significantly wider field of view (4x area) and higher sensitivity (20x) with high relative stability. The unprecedented ability to survey large regions with absolutely registered JHK(L) imaging will give renewed impetus to systematic studies of the more global aspects of the star formation process which had heretofore been stalled by the complexity of the observations and the attendant data reduction which are required to adequately sample the full luminosity range over a FOV measured in tens of arc minutes in the presence of heavy, patchy extinction. Statistically significant star counts, with derived mass and luminosity functions, and the detailed distribution of the attendant gas and dust will all be amenable to careful study for a regions of star formation covering a wide range in distance, total mass, and age.

Service

As an Infrared Imaging Scientist at KPNO, Merrill oversees the IR imagers and attendant visitor support at KPNO, including instrument set-ups and observer checkouts, and is the point of contact on performance issues for both proposers and the TAC during the proposal cycle. He is project scientist for the KPNO SQIID upgrade to 512x512 InSb and actively involved with the shake-down and deployment of new IR instrumentation. As the responsible scientist for user support of IR data reductions, he advises observers, programs and supports data reduction scripts, and interacts with the IRAF programming group to improve and extend IR specific capabilities within IRAF. As package scientist for the the next generation Gemini/NOAO Array Controller project and (with I. Gatley) responsible scientist for the Aladdin InSb 1024X1024 IR array R&D effort, Merrill plays a significant role in developing the deploying state of the art IR detection capability to the wider community. Merrill continues as advisor to Gemini for IR instrumentation - detectors, array controllers, limiting performance and observation techniques. Merrill has been an active participant in outreach activities within the local schools, including teaching classes and coaching Science Olympiad teams, and at scientific meetings.


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NOAO is operated by the Association of U niversities for Research in Astronomy (AURA), Inc. under cooperative agreement with the National Science Foundation
Posted: 06Dec1996