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We investigate the physical structure and conditions of photodissociation regions (PDRs) and molecular gas within the Pillars of Creation in the Eagle Nebula using SOFIA FEEDBACK observations of the [C II] 158 micron line. These observations are velocity resolved to 0.5 km s$^{-1}$ and are analyzed alongside a collection of complimentary data with similar spatial and spectral resolution: the [O I] 63 micron line, also observed with SOFIA, and rotational lines of CO, HCN, HCO$^{+}$, CS, and N$_2$H$^{+}$. Using the superb spectral resolution of SOFIA, APEX, CARMA, and BIMA, we reveal the relationships between the warm PDR and cool molecular gas layers in context of the Pillars' kinematic structure. We assemble a geometric picture of the Pillars and their surroundings informed by illumination patterns and kinematic relationships and derive physical conditions in the PDRs associated with the Pillars. We estimate an average molecular gas density $n_{{\rm H}_2} \sim 1.3 \times 10^5$ cm$^{-3}$ and an average atomic gas density $n_{\rm H} \sim 1.8 \times 10^4$ cm$^{-3}$ and infer that the ionized, atomic, and molecular phases are in pressure equilibrium if the atomic gas is magnetically supported. We find pillar masses of 103, 78, 103, and 18 solar masses for P1a, P1b, P2, and P3 respectively, and evaporation times of $\sim$1-2 Myr. The dense clumps at the tops of the pillars are currently supported by the magnetic field. Our analysis suggests that ambipolar diffusion is rapid and these clumps are likely to collapse within their photoevaporation timescales., Comment: 42 pages, 16 figures. Accepted for publication in The Astronomical Journal

We present a new set of measurements obtained with the Combined Array for Research in Millimeter-wave Astronomy (CARMA) of Jupiter's microwave thermal emission near the 1.3 cm ammonia (NH$_{3}$) absorption band. We use these observations to investigate the ammonia mole fraction in the upper troposphere, near $0.3 < P < 2$ bar, based on radiative transfer modeling. We find that the ammonia mole fraction must be $\sim2.4\times 10^{-4}$ below the NH$_{3}$ ice cloud, i.e., at $0.8 < P < 8$ bar, in agreement with results by de Pater et al. (2001, 2016a). We find the NH$_{3}$ cloud-forming region between $0.3 < P < 0.8$ bar to be globally sub-saturated by 55% on average, in accordance with the result in Gibson et al. (2005). Although our data are not very sensitive to the region above the cloud layer, we are able to set an upper limit of $2.4\times 10^{-7}$ on the mole fraction here, a factor of $\sim$10 above the saturated vapor curve., Comment: 11 pages, 5 figures, submitted to AJ. For data behind Figure 1, see https://www.astro.umd.edu/~rkarim/SZA_Jupiter/

We prove that every infinite, discrete abelian group admits a pair of $I_0$ sets whose union is not $I_0$. In particular, this implies that every such group contains a Sidon set that is not $I_{0}$.

A subset $E$ of a discrete abelian group is called $\epsilon $-Kronecker if all $E$-functions of modulus one can be approximated to within $\epsilon$ by characters. $E$ is called a Sidon set if all bounded $E$-functions can be interpolated by the Fourier transform of measures on the dual group. As $\epsilon$-Kronecker sets with $\epsilon <2$ possess the same arithmetic properties as Sidon sets, it is natural to ask if they are Sidon. We use the Pisier net characterization of Sidonicity to prove this is true., Comment: 7 pages

For any three element set of positive integers, $\{a,b,n\}$, with $a

Various upper and lower bounds are provided for the (angular) Kronecker constants of sets of integers. Some examples are provided where the bounds are attained. It is proved that 5=16 bounds the angular Kronecker constants of 3-element sets of positive integers. However, numerous examples suggest that the minimum upper bound is 1=4 for 3-element sets of positive integers.

We present spectroscopic rotation velocities (v sin i) for 56 M dwarf stars using high resolution HET HRS red spectroscopy. In addition we have also determined photometric effective temperatures, masses and metallicities ([Fe/H]) for some stars observed here and in the literature where we could acquire accurate parallax measurements and relevant photometry. We have increased the number of known v sin is for mid M stars by around 80% and can confirm a weakly increasing rotation velocity with decreasing effective temperature. Our sample of v sin is peak at low velocities (~3 km/s). We find a change in the rotational velocity distribution between early M and late M stars, which is likely due to the changing field topology between partially and fully convective stars. There is also a possible further change in the rotational distribution towards the late M dwarfs where dust begins to play a role in the stellar atmospheres. We also link v sin i to age and show how it can be used to provide mid-M star age limits. When all literature velocities for M dwarfs are added to our sample there are 198 with v sin i less than or equal to 10 km/s and 124 in the mid-to-late M star regime (M3.0-M9.5) where measuring precision optical radial-velocities is difficult. In addition we also search the spectra for any significant Halpha emission or absorption. 43% were found to exhibit such emission and could represent young, active objects with high levels of radial-velocity noise. The tables presented here will aid any future M star planet search target selection to extract stars that will exhibit low radial-velocity jitter., Comment: 22 pages, 11 figures, 4 tables, Accepted for publication in ApJ

We have designed and tested an in-plane echelle spectrograph configured to investigate precision radial velocities from ground-based near-infrared observations. The spectrograph operates across the spectral range of 0.9-1.7 mm at a spectral resolution of R = 50,000, and uses a liquid nitrogen-cooled HAWAII 1K detector. Repeated measurements of the Earth's rotation via integrated Sunlight with two different instrument arrangements in the near infrared Y band have produced radial velocities with ~10 m/s RMS over a period of several hours. The most recent instrument configuration has achieved an unbinned RMS of 7 m/s and suggests that infrared radial velocity precisions may be able to approach those achieved at optical wavelengths., Comment: 18 pages, 8 figures, accepted for publication in PASP

We report the discovery of a substellar-mass companion to the K0-giant HD 17092 with the Hobby-Eberly Telescope. In the absence of any correlation of the observed 360-day periodicity with the standard indicators of stellar activity, the observed radial velocity variations are most plausibly explained in terms of a Keplerian motion of a planetary-mass body around the star. With the estimated stellar mass of 2.3Msun, the minimum mass of the planet is 4.6MJ. The planet's orbit is characterized by a mild eccentricity of e=0.17 and a semi-major axis of 1.3 AU. This is the tenth published detection of a planetary companion around a red giant star. Such discoveries add to our understanding of planet formation around intermediate-mass stars and they provide dynamical information on the evolution of planetary systems around post-main sequence stars., Comment: 13 pages, 3 figures, 2 tables. Submitted to ApJ

Let $e^{2\pi i\Q}$ denote the set of roots of unity. We consider subsets $E\subset e^{2\pi i\Q}$ that are quasi-independent or algebraically independent (as subsets of the discrete plane). A bijective map on $e^{2\pi i\Q}$ preserves the algebraically independent sets iff it preserves the quasi-independent sets, and those maps are characterized. The effect on the size of quasi-independent sets in the $n^{th}$ roots of unity $Z_n$ of increasing a prime factor of $n$ is studied.

High resolution echelle spectra of PW And (HD~1405) have been taken during eight observing runs from 1999 to 2002. The detailed analysis of the spectra allow us to determine its spectral type (K2V), mean heliocentric radial velocity (V_hel = -11.15 km/s) rotational velocity (vsin{i} = 22.6 km/s), and equivalent width of the lithium line 6707.8 AA (EW(LiI) = 273 mAA). The kinematic (Galactic Velocity (U, V, W)) confirms its membership of the Local Association moving group, in agreement with the age (30 to 80 Myrs) inferred from the color magnitude diagram and the lithium equivalent width. Photospheric activity (presence of cool spots that disturb the profiles of the photospheric lines) has been detected as changes in the the bisectors of the cross correlation function (CCF) resulting of cross-correlate the spectra of PW And with the spectrum of a non active star of similar spectral type. These variations of the CCF bisectors are related to the variations in the measured radial velocities and are modulated with a period similar to the photometric period of the star. At the same time, chromospheric activity has been analyzed, using the spectral subtraction technique and simultaneous spectroscopic observations of the H_alpha, H_beta, NaI D_1 and D_2$, HeI D_3, MgI b triplet, CaII H&K, and CaII infrared triplet lines. A flare was observed during the last observing run of 2001, showing an enhancement in the observed chromospheric lines. A less powerful flare was observed on 2002 August 23. The variations of the chromospheric activity indicators seem to be related to the photospheric activity. A correlation between radial velocity, changes in the CCF bisectors and equivalent width of different chromospheric lines is observed with a different behaviour between epochs 1999, 2001 and 2002., Comment: Latex file with 20 pages, 21 figures tar'ed gzip'ed. Full postscript (text, figures and tables) available at http://www.ucm.es/info/Astrof/users/dmg/pub_dmg.html Accepted for publication in: Astronomy & Astrophysics (A&A)

We present results from a 221.9 ks Chandra exposure of the HDF-N and its vicinity, concentrating on the 8.6' X 8.7' area covered by the Caltech Faint Field Galaxy Redshift Survey (the `Caltech area'). The minimum detectable fluxes in the 0.5-2 keV and 2-8 keV bands are 1.3e-16 cgs and 6.5e-16 cgs, respectively and a total of 82 sources are detected. More than 80% of the extragalactic X-ray background in the 2-8 keV band is resolved. Redshifts are available for 96% of the sources with R<23; the redshift range is 0.1-3.5 with most sources having z < 1.5. Eight of the X-ray sources are located in the HDF-N itself, including two not previously reported. A population of X-ray faint, optically bright, nearby galaxies emerges at soft-band fluxes of ~< 3e-16 cgs. We set the tightest constraints to date on the X-ray emission properties of microJy radio sources, mid-infrared sources detected by ISO, and very red (R-K_s > 5.0) objects. Where both the infrared and the X-ray coverage are deepest, 75% of the X-ray sources are detected by ISO; the high X-ray to infrared matching rate bodes well for future sensitive infrared observations of faint X-ray sources. Four of the 33 very red objects that have been identified in the Caltech area by Hogg et al. (2000) are detected in X-rays; these four are among our hardest Chandra sources, and we argue that they contain moderately luminous obscured AGN. Overall, however, the small Chandra detection fraction suggests a relatively small AGN content in the optically selected very red object population. (Abridged), Comment: 75 pages, ApJ, in press, version with full resolution figures available from http://www.astro.psu.edu/users/niel/hdf/hdf-chandra.html

We present results from a study of 2-8 keV X-ray sources detected by the Advanced CCD Imaging Spectrometer (ACIS) instrument on the Chandra X-ray Observatory in the field of the z=0.516 cluster CRSS J0030.5+2618. In our 63.5 arcmin^2 search area, we detect 10 sources with 2-8 keV fluxes down to approximately 4x10^{-15} erg cm^{-2} s$^{-1}; our lowest flux sources are approximately 10 times fainter than those previously available for study in this band. Our derived source density is about an order of magnitude larger than previous source counts above 2 keV, although this density may be enhanced somewhat due to the presence of the cluster. We detail our methods for source detection and characterization, and we show that the resulting source list and parameters are robust. We have used the Marcario Low Resolution Spectrograph on the Hobby-Eberly Telescope to obtain optical spectra for several of our sources; combining these spectra with archival data we find that the sources appear to be active galaxies, often with narrow permitted lines, red optical continua or hard X-ray spectra. Four of the X-ray sources are undetected to R=21.7; if they reside in L* galaxies they must have z > 0.55-0.75 and hard X-ray luminosities of L_{2-8} > 4x10^{42} erg s^{-1}. We detect all but one of our 2-8 keV sources in the 0.2-2 keV band as well. This result extends to significantly lower fluxes the constraints on any large, completely new population of X-ray sources that appears above 2-3 keV., Comment: 22 pages, AJ, in press

This paper describes spectra of quasar candidates acquired during the commissioning phase of the Low-Resolution Spectrograph of the Hobby-Eberly Telescope. The objects were identified as possible quasars from multicolor image data from the Sloan Digital Sky Survey. The ten sources had typical r' magnitudes of 19-20, except for one extremely red object with r' of approximately 23. The data, obtained with exposure times between 10 and 25 minutes, reveal that the spectra of four candidates are essentially featureless and are not quasars, five are quasars with redshifts between 2.92 and 4.15 (including one Broad Absorption Line quasar), and the red source is a very late M, Comment: Accepted for publication in P.A.S.P., 10 pages including 2 figures

2RE J0743+224 (BD +23 1799) is a chromospherically active star selected by X-rays and EUV emission detected in the Einstein Slew Survey and ROSAT Wide Field Camara (WFC) all sky survey, and classified as single-lined spectroscopic binary by (Jeffries et al. 1995). We present here high resolution echelle spectroscopic observations of this binary, obtained during a 10 night run 12-21 January 1998 using the 2.1m telescope at McDonald Observatory. These observations reveal it is a double-lined spectroscopic binary. A dramatic increase in the chromospheric emissions (H_alpha and Ca II IRT lines) is detected during the observations. Several arguments favor the interpretation of this behavior as an unusual long-duration flare. First the temporal evolution of the event is similar to the observed in other solar and stellar flares, with an initial impulsive phase characterized by a strong increase in the chromospheric lines (the H_alpha EW change in a factor of 5 in only one day) and thereafter, the line emission decreased gradually over several days. Second, a broad component in the H_alpha line profile is observed just at the beginning of the event. Third, the detection of the He I D_{3} in emission and a filled-in He I 6678 A. We detect a Li I 6708 A line enhancement which is clearly related with the temporal evolution of the flare. The maximum Li I enhancement occurs just after the maximum chromospheric emission observed in the flare. We suggest that this Li I is produced by spallation reactions in the flare. This is the first time that such LiI enhancement associate with a stellar flare is reported, and probably the long-duration of this flare is a key factor for this detection., Comment: Latex file with 5 figures tar'ed gzip'ed. Full postscript (text & figures) available at http://www.ucm.es/OTROS/Astrof/pub_dmg.html, to be published in ASP Conf. Ser., Solar and Stellar Activity: Similarities and Differences (meeting dedicated to Brendan Byrne, Armagh 2-4th Sep. 1998) C.J. Butler and J.G. Doyle, eds

We have started a high resolution optical observation program dedicated to the study of chromospheric activity in weak-lined T Tauri stars (WTTS) recently discovered by the ROSAT All-Sky Survey (RASS). It is our purpose to quantify the phenomenology of the chromospheric activity of each star determining stellar surface fluxes in the more important chromospheric activity indicators (Ca II H & K, H_beta, H_alpha, Ca II IRT) as well as obtain the Li I abundance, a better determination of the stellar parameters, spectral type, and possible binarity. A large number of WTTS have been discovered by the RASS in and around differen star formation clouds.Whether these stars are really WTTS, or post-TTS, or even young main sequence stars is a matter of ongoing debate. However, we have centered our study only on objects for which very recent studies, of Li I abundance (greater than Pleiads of the same spectral type) or radio properties, clearly confirmed their pre-main sequence (PMS) nature. In this contribution we present preliminary results of our January 1998 high resolution echelle spectroscopic observations at the 2.1m telescope of the McDonald Observatory. We have analysed, using the spectral subtraction technique, the H_alpha and Ca II IRT lines of six WTTS (RXJ0312.8-0414NW, SE; RXJ0333.1+1036; RXJ0348.5+0832; RXJ0512.0+1020; RXJ0444.9+2717) located in and around the Taurus-Auriga molecular clouds. A broad and variable double-picked H_alpha emission is observed in RXJ0444.9+2717. Emission above the continuum in H_alpha and Ca II IRT lines is detected in RXJ0333.1+1036 and a filling-in of these lines is present in the rest of the stars. Our spectral type and Li I EW deterninations confirm the PMS nature of these objects., Comment: Latex file with 5 figures tar'ed gzip'ed. Full postscript (text & figures) available at http://www.ucm.es/OTROS/Astrof/pub_dmg.html, to be published in ASP Conf. Ser., Solar and Stellar Activity: Similarities and Differences (meeting dedicated to Brendan Byrne, Armagh 2-4th Sep. 1998) C.J. Butler and J.G. Doyle, eds

We report the detection of a long-duration optical flare in the recenltly discovered, X-ray selected, chromospherically binary 2RE J0743+224. The high resolution echelle spectroscopic observations taken in 12-21th January 1998 exhibit a dramatic increase in the chromospheric emissions (H_alpha and CaII IRT lines) that we interpret as a flare based on: the temporal evolution of the event, the broad component observed in the H_alpha line profile, the detection of the HeI D_3 in emission and a filled-in HeI 6678 A. During these obsevations we detect a LiI 6708 A line enhancement which is clearly related with the temporal evolution of the flare. The maximum LiI enhancement occurs just after the maximum chromospheric emission observed in the flare. A significant increase of the 6Li/7Li isotopic ratio is also detected. From all this we suggest that this LiI enhancement is produced by spallation reactions during the flare. This is the first time that such LiI enhancement associate with a stellar flare is reported, and probably the long-duration of this flare is a key factor for this detection. A large fraction of the stellar surface seems to be covered by starspots during the event, as we deduce for the analysis of the TiO 7055 A band. Thus taking into account that LiI line is very temperature sensitive, we can not discard that the LiI variations are related the presence of starspots. However, the correlation with the temporal evolution of the flare, lack of detection of changes in the other photospheric absorption lines, and the large changes observed in the core of the LiI, as predict the models, argue in favour of the hypothesis that the LiI is produced during the flare., Comment: Latex file with 5 figures tar'ed gzip'ed. Full postscript (text and figures) available at http://www.ucm.es/OTROS/Astrof/fgkmsl/rej0743.html Presented at the: 192nd Meeting of the AAS (June 7-11 1998), to be published in Bull. American Astron. Soc

We have developed an optical design for a high resolution spectrograph in response to NASA's call for an extreme precision Doppler spectrometer (EPDS) for the WIYN telescope. Our instrument covers a wavelength range of 380 to 930 nm using a single detector and with a resolution of 100,000. To deliver the most stable spectrum, we avoid the use of an image slicer, in favor of a large (195 mm diameter) beam footprint on a 1x2 mosaic R4 Echelle grating. The optical design is based on a classic white pupil layout, with a single parabolic mirror that is used as the main and transfer collimator. Cross dispersion is provided by a single large PBM2Y glass prism. The refractive camera consists of only four rotationally symmetric lenses made from i-Line glasses, yet delivers very high image quality over the full spectral bandpass. We present the optical design of the main spectrograph bench and discuss the design trade-offs and expected performance.

We present an ongoing effort to characterize chemistry in Mars' atmosphere in multiple seasons on timescales longer than spaceflight missions through coordinated efforts by GSFC's HIPWAC spectrometer and Mars Express SPICAM, archival measurements, and tests/application of photochemical models. The trace species ozone (03) is an effective probe of Mars' atmospheric chemistry because it is destroyed by odd-hydrogen species (HOx, from water vapor photolysis). Observed ozone is a critical test for specific predictions by 3-D photochemical models (spatial, diurnal, seasonal). Coordinated measurements by HIPWAC and SPICAM quantitatively linked mission data to the 23-year GSFC ozone data record and also revealed unanticipated inter-decadal variability of same-season ozone abundances, a possible indicator of changing cloud activity (heterogeneous sink for HOx). A detailed study of long-term conditions is critical to characterizing the predictability of Mars' seasonal chemical behavior, particularly in light of the implications of and the lack of explanation for reported methane behavior.