April 1998 • Volume 15, Number 2 SPACE TELESCOPE SCIENCE INSTITUTE Highlights of this issue: • Pure Parallel Program — page 5 • NGST-DRM — page 14 • Outreach Programs Newsletter — page 6 A New Director for STScI URA has selected Steven V. graduate student, he designed and Heidelberg, where two generations of W. Beckwith as the next constructed a thermal IR photometer wide-field IR cameras were built for ADirector of the Space that he used at Mount Wilson. His the Calar Alto 3.5 m telescope. The Telescope Science Institute. thesis dealt with molecular hydrogen first observations with these cameras We were fortunate to have a number emission from many different sources, led to detection of a starburst galaxy at of outstanding individuals who were such as planetary nebulae, T Tauri redshift 2.4 and the start of the Calar willing to assume the responsibilities stars, and the ISM. He continued this Alto Deep Imaging Survey, a search of running STScI. The short list of line of work when he went to Cornell candidates remains confidential, of and built a new spectrometer for the course, but Steve’s qualifications Kuiper Airborne Observatory to study demonstrate why he was a first choice. molecular lines and broad dust features Steve comes to STScI from the in the thermal IR. Max Planck Institut für Astronomie The detection of scattered light from in Heidelberg, where he has been the pre-main sequence object HL Tauri Managing Director since 1994, and a (Beckwith et al. 1986, ApJ, 287, 793) Director since 1991. His academic and subsequently the millimeter-wave career is summarized as: emission from the same object (Beckwith et al. 1986, ApJ, 309, 755) 1973 — B.S. in Engineering Physics stimulated his work on circumstellar from Cornell (in 3 years) disks. The disk mass estimated from 1978 — Ph.D. in Physics from Caltech the dust emission appeared to be sufficient to build a planetary system, 1978-1984 — Assistant Professor of and a more thorough survey (Beckwith Astronomy, Cornell Steven Beckwith (left) and Bob Williams (right) at a recent et al. 1990, AJ, 99, 924) demonstrated visit of Steven to STScI. 1984-1989 — Associate Professor of that almost half the young stars in Astronomy, Cornell Taurus had circumstellar disks that could lead to planets. The study of for optical emission-line galaxies at 1989-1992 — Professor of Astronomy, these disks and their properties has redshifts greater than 5. Cornell been fundamental for estimating the Upon coming to Heidelberg, Steve’s Among other distinctions, Steve was number of other planetary systems in goals were to equip the Calar Alto an Alfred P. Sloan Fellow from 1982 the Galaxy. This study of proto- Observatory, operated by MPI to 1985. planetary disks continued with ISO Heidelberg, with modern instrumenta- and with instrument development for tion by decreasing the time and cost Steve is well known as an infrared the Very Large Telescope Interferom- needed for instrument projects, to astronomer and developer of instru- eter (VLTI). With the VLTI, his group establish collaborations with other mentation. While at Caltech as a will attempt to resolve circumstellar institutes, and to diversify the staff of disks at 10 and 20 microns. about 190 people. These changes led to Editor’s Note: Steve acquired an interest in early a faster pace of scientific output by a This article is based on a letter galaxy formation while at Cornell and staff acting with greater self-direction. Dr. Beckwith sent to the AURA Director Search Committee as part of his started a project to observe the IR New instruments have included IR application to become Director of signatures of primeval galaxies. This continued page 4 STScI. It is excerpted with permission. work continued after he went to Newsletter • Space Telescope Science Institute Director’s Perspective Bob Williams ST is entering an important phase in the life of the mission. In the coming year decisions will be taken that will affect how the telescope will be configured and operated in the final years after the last scheduled servicing mission in H 2002. The cryogenic cooler proposed for installation on NICMOS during the third servicing mission in 1999 will be flight tested this October on the same Shuttle mission that will carry Sen. John Glenn back into space. The construction of a new facility-class imager, WFC3, recommended by the same external advisory committee that evaluated the 2002 instrument propos- als, will be defined and developed if the Project is successful in identifying adequate funding, as now seems likely. A realistic plan for operating HST far more cheaply than currently possible, beyond 2002 when the servicing missions (with their new hardware and associated commanding software) are not the large cost drivers they now are, is being developed jointly by the Project and the Institute. Called ‘Cheap Ops’ by us, the implementation of a substantially cheaper way of operating HST is absolutely essential if the mission is to be extended until 2010 and for the timely development of the Next Generation Space Telescope. The larger question of how best to maintain the high scientific productivity of HST in the era when it must be operated cheaply, when telescope hardware failures cannot be serviced and when budgetary constraints will not allow extensive software maintenance or development, is an important matter that will be addressed in the ‘HST Second Decade Study’ that is being conducted by the Institute with wide community participation. All of the above items are critical in defining what HST’s capabilities will be and how it can best be used scientifically after 2002. It is hoped that this epoch will also see collaborative programs jointly carried out on HST, SIRTF, and NGST. Our experi- ence with HST has demonstrated the important effect that a highly productive mission can have on other related NASA space astronomy missions. I would say that the essential ingredients of this productivity have been: the unique capabilities of HST; broad community support, including European participation in the HST Project; adequate data reduction funding; and an aggressive outreach and education program. Short term, the NASA data reduction funds for HST are projected to be very healthy in the coming years, and this augurs well for the vital soft money infrastructure that has developed in U.S. astronomy associated with HST. Finally, we are very pleased with AURA’s announcement that the next STScI Director will be Dr. Steven Beckwith, currently Managing Director of the Max- Planck-Institut für Astronomie in Heidelberg. Steve will assume his new responsibilities in early September, when I stand down at the end of my current term to devote more of my time to research activity. We note two corrections related to items in the previous (1998 January) Newsletter. First, in the article on NGC 5253 by Daniela Calzetti, what should have been Figure 1b appears as Figure 2. Therefore what is labeled as an Hα image is really through the F814W filter. The error occurred in production and is not the fault of the author. Second, we would like to note that the appreciation of Chris Skinner in the January Newsletter was based on an obituary of Chris published in Astronomy and Geophysics, a publication of the Royal Astronomical Society. 2 April 1998 Optical Jets in Blazars and Radio Galaxies Riccardo Scarpa and C. Megan Urry [email protected], [email protected] L Lacertae objects are through the jet are responsible for believed to be radio galaxies electron reacceleration. Bviewed along their radio jet The first object we observed, PKS axis. As part of an HST snapshot 0521-365, has been known to have a survey of BL Lacertae objects, we used large optical jet for some time WFPC2 to observe the optical jet of (Danziger et al. 1979). At HST two well-known extragalactic radio resolution (Fig. 1), the optical jet sources, PKS 0521-365 and 3C371. shows a knotty structure; it is resolved Both are relatively nearby (z=0.055 also orthogonally to the axis, and has and 0.050, respectively), and can be an almost constant transversal size of studied with unprecedented detail ~1.2 arcsec. The total magnitude of the ± with HST. jet is mR=19.9 0.2. Assuming there is In the radio band, jets are observed equipartition of energy among particles in hundreds of radio galaxies and and magnetic field, we derive for each quasars. Based on their broad band knot the intensity of the magnetic field. flux energy distribution, and the high Surprisingly, despite the increasing Fig. 1: The optical image (grayscale) overplotted with a polarization that characterize the jet distance from the center, the inferred 2-cm radio map (contour) of the jet of PKS 0521-365. The optical image was obtained in 300 seconds with the emission, astronomers think the intensity is almost constant, WFPC2 camera plus the F702W filter. The host galaxy and emission is produced by relativistic B ~ 4 × 10-4 Gauss. the bright central point source (indicated by two thick electrons in a magnetic field via the The optical and radio (Keel 1986) black pointers) has been subtracted from the image. The synchrotron process. Synchrotron images are similar, with the general total length of the jet is 5.8 arcsec. North is approximately emission is very efficient at producing shape and the total length of the jet on the top and east on the left. radio waves, while to produce optical almost exactly reproduced in the two radiation the electrons must be bands. This is particularly true for the extremely energetic (up to ~107 times brightest knot, which is well resolved their rest energy). The higher the in both bands.