Shuttle Ground Operations Efficiencies/Technologies Study (SGOE/T). Volume 5: Technical Information Sheets (TIS)

The Technology Information Sheet was assembled in database format during Phase I. This document was designed to provide a repository for information pertaining to 144 Operations and Maintenance Instructions (OMI) controlled operations in the Orbiter Processing Facility (OPF), Vehicle Assembly Building (VAB), and PAD. It provides a way to accumulate information about required crew sizes, operations task time duration (serial and/or parallel), special Ground Support Equipment (GSE). required, and identification of a potential application of existing technology or the need for the development of a new technolgoy item

Shuttle Ground Operations Efficiencies/Technologies (SGOE/T) study. Volume 2: Ground Operations evaluation

The Ground Operations Evaluation describes the breath and depth of the various study elements selected as a result of an operational analysis conducted during the early part of the study. Analysis techniques used for the evaluation are described in detail. Elements selected for further evaluation are identified; the results of the analysis documented; and a follow-on course of action recommended. The background and rationale for developing recommendations for the current Shuttle or for future programs is presented

Shuttle Ground Operations Efficiencies/Technologies (SGOE/T) study. Volume 1: Executive summary

Methods and technolgoy were defined to reduce the overall operations cost of a major space program. Space Shuttle processing at Kennedy Space Center (KSC) was designed as the working model that would be the source of the operational information. Methods of improving efficiency of ground operations were assessed and technology elements that could reduce cost identified. Emphasis is on: (1) specific technology items and (2) management approaches required to develop and support efficient ground operations. Prime study results are to be recommendations on how to achieve more efficient operations and identification of existing or new technology that would make vehicle processing in both the current program and future programs more efficient and, therefore, less costly

Near Infrared Spectroscopy of Young Brown Dwarfs in Upper Scorpius

Spectroscopic follow-up is a pre-requisite for studies of the formation and early evolution of brown dwarfs. Here we present IRTF/SpeX near-infrared spectroscopy of 30 candidate members of the young Upper Scorpius association, selected from our previous survey work. All 24 high confidence members are confirmed as young very low mass objects with spectral types from M5 to L1, 15-20 of them are likely brown dwarfs. This high yield confirms that brown dwarfs in Upper Scorpius can be identified from photometry and proper motions alone, with negligible contamination from field objects (<4%). Out of the 6 candidates with lower confidence, 5 might still be young very low mass members of Upper Scorpius, according to our spectroscopy. We demonstrate that some very low mass class II objects exhibit radically different near infrared (0.6 - 2.5micron) spectra from class III objects, with strong excess emission increasing towards longer wavelengths and partially filled in features at wavelengths shorter than 1.25micron. These characteristics can obscure the contribution of the photosphere within such spectra. Therefore, we caution that near infrared derived spectral types for objects with discs may be unreliable. Furthermore, we show that the same characteristics can be seen to some extent in all class II and even a significant fraction of class III objects (~40%), indicating that some of them are still surrounded by traces of dust and gas. Based on our spectra, we select a sample of objects with spectral types of M5 to L1, whose near-infrared emission represents the photosphere only. We recommend the use of these objects as spectroscopic templates for young brown dwarfs in the future.Comment: 12 pages, 9 figures, Accepted in MNRA

Cool White Dwarfs Revisited -- New Spectroscopy and Photometry

In this paper we present new and improved data on 38 cool white dwarfs identified by Oppenheimer et al. 2001 (OHDHS) as candidate dark halo objects. Using the high-res spectra obtained with LRIS, we measure radial velocities for 13 WDs that show an H alpha line. We show that the knowledge of RVs decreases the UV-plane velocities by only 6%. The radial velocity sample has a W-velocity dispersion of sig_W = 59 km/s--in between the values associated with the thick disk and the stellar halo. We also see indications for the presence of two populations by analyzing the velocities in the UV plane. In addition, we present CCD photometry for half of the sample, and with it recalibrate the photographic photometry of the remaining WDs. Using the new photometry in standard bands, and by applying the appropriate color-magnitude relations for H and He atmospheres, we obtain new distance estimates. New distances of the WDs that were not originally selected as halo candidates yield 13 new candidates. On average, new distances produce velocities in the UV plane that are larger by 10%, with already fast objects gaining more. Using the new data, while applying the same UV-velocity cut (94 km/s) as in OHDHS, we find a density of cool WDs of 1.7e-4 pc^-3, confirming the value of OHDHS. In addition, we derive the density as a function of the UV-velocity cutoff. The density (corrected for losses due to higher UV cuts) starts to flatten out at 150 km/s (0.4e-4 pc^-3), and is minimized (thus minimizing a possible non-halo contamination) at 190 km/s (0.3e-4 pc^-3). These densities are in a rough agreement with the estimates for the stellar halo WDs, corresponding to a factor of 1.9 and 1.4 higher values.Comment: Accepted to ApJ. New version contains some additional data. Results unchange

Observations of Mira stars with the IOTA/FLUOR interferometer and comparison with Mira star models

We present K'-band observations of five Mira stars with the IOTA interferometer. The interferograms were obtained with the FLUOR fiber optics beam combiner, which provides high-accuracy visibility measurements in spite of time-variable atmospheric conditions. For the M-type Miras X Oph, R Aql, RU Her, R Ser, and the C-type Mira V CrB we derived the uniform-disk diameters 11.7mas, 10.9mas, 8.4mas, 8.1mas, and 7.9mas (+/- 0.3mas), respectively. Simultaneous photometric observations yielded the bolometric fluxes. The derived angular Rosseland radii and the bolometric fluxes allowed the determination of effective temperatures. For instance, the effective temperature of R Aql was determined to be 2970 +/- 110 K. A linear Rosseland radius for R Aql of (250 +100/-60) Rsun was derived from the angular Rosseland radius of 5.5mas +/- 0.2mas and the HIPPARCOS parallax of 4.73mas +/- 1.19mas. The observations were compared with theoretical Mira star models of Bessel et al. (1996) and Hofmann et al. (1998). The effective temperatures of the M-type Miras and the linear radius of R Aql indicate fundamental mode pulsation.Comment: 12 pages, 4 postscript figure

Shuttle ground operations efficiencies/technologies study. Volume 4: Preliminary Issues Database (PIDB) catalog

The Preliminary Issues Database (PIDB) was assembled very early in the study as one of the fundamental tools to be used throughout the study. Data was acquired from a variety of sources and compiled in such a way that the data could be easily sorted in accordance with a number of different analytical objectives. The system was computerized to significantly expedite sorting and make it more usable. The information contained in the PIDB is summarized and the reader is provided with the capability to manually find items of interest

Measurement of Orbital Decay in the Double Neutron Star Binary PSR B2127+11C

We report the direct measurement of orbital period decay in the double neutron star pulsar system PSR B2127+11C in the globular cluster M15 at the rate of $(-3.95 \pm 0.13) \times 10^{-12}$, consistent with the prediction of general relativity at the $\sim 3$ level. We find the pulsar mass to be $m_p = (1.358 \pm 0.010) M_\odot$ and the companion mass $m_c = (1.354 \pm 0.010) M_\odot$. We also report long-term pulse timing results for the pulsars PSR B2127+11A and PSR B2127+11B, including confirmation of the cluster proper motion.Comment: 12 pages, 4 figures, accepted for publication in ApJ

Rotation and activity of pre-main-sequence stars

We present a study of rotation (vsini) and chromospheric activity (Halpha EW) based on an extensive set of high-resolution optical spectra obtained with MIKE on the 6.5m Magellan Clay telescope. Our targets are 74 F-M dwarfs in the young stellar associations Eta Cha, TW Hydrae, Beta Pic, and Tuc-Hor, spanning ages from 6 to 30 Myr. While the Halpha EW for most F and G stars are consistent with pure photospheric absorption, most K and M stars show chromospheric emission. By comparing Halpha EW in our sample to results in the literature, we see a clear evolutionary sequence: Chromospheric activity declines steadily from the T Tauri phase to the main sequence. Using activity as an age indicator, we find a plausible age range for the Tuc-Hor association of 10-40 Myr. Between 5 and 30 Myr, we do not see evidence for rotational braking in the total sample, thus angular momentum is conserved, in contrast to younger stars. This difference indicates a change in the rotational regulation at 5-10 Myr, possibly because disk braking cannot operate longer than typical disk lifetimes, allowing the objects to spin up. The rotation-activity relation is flat in our sample; in contrast to main-sequence stars, there is no linear correlation for slow rotators. We argue that this is because young stars generate their magnetic fields in a fundamentally different way from main-sequence stars, and not just the result of a saturated solar-type dynamo. By comparing our rotational velocities with published rotation periods for a subset of stars, we determine ages of 13 (7-20) Myr and 9 (7-17} Myr for the Eta Cha and TWA associations, respectively, consistent with previous estimates. Thus we conclude that stellar radii from evolutionary models by Baraffe et al. (1998) are in agreement with the observed radii within +-15%. (abridged)Comment: 40 pages, 8 figures, ApJ, in pres