The 25th New Mexico Symposium



Dust to Dust: Grain Formation & Evolution in Classical Novae

J. Bornak, T. E. Harrison (NMSU) & K. D. Gordon (STScI)

Dust masses derived from observations of classical novae often equal the total ejected mass. This is unphysical. We propose the flaw resides in assuming that the dust is in homogeneous shells. Images of old novae show that the ejected gas is extremely inhomogeneous. We discuss results of using the advanced dust modeling code, DIRTY, to over 200 days of OIR photometry and spectroscopy of Nova Cen 1991 (V868 Cen), a classical novae with dust formation and strong evidence of inhomogeneous ejecta.

EVLA Observations of the Orion Hot Core: a Taste of the Future.

NRAO-NM Staff, presented by Claire Chandler

A 12-station subset of the final EVLA correlator has been undergoing extensive testing and system integration leading up to the final shutdown of the VLA correlator in January 2010. To illustrate the future power of the EVLA we have used this 12-station correlator to observe the Orion Hot Core at a wavelength of 1.2 cm, covering a total bandwidth of 3 GHz with 24,000 channels (a spectral resolution of ~1.5 km/s). The resulting cube contains emission from many transitions of ammonia, methanol, and sulphur dioxide, each of which shows a different spatial distribution within the Hot Core. The data cube is publicly available.

Magdalena Ridge Observatory Interferometer: Advancing to First Light and New Science

M. Creech-Eakman, V. Romero, C. Cormier (NMT), C. Haniff, D. Buscher, J. Young (Cavendish Laboratory, Cambridge), D. Westpfahl & the MROI Team (NMT)

We report on the final stages of the design and build efforts for the Magdalena Ridge Observatory Interferometer. Located at an elevation of 10,500 ft, approximately 1 hour west of Socorro, NM, the observatory is being built by the New Mexico Institute of Mining and Technology in close collaboration with scientists from the Cavendish Laboratory at the University of Cambridge. The MROI is being designed and built by a distributed team of about 25 scientists and engineers at these two universities who are actively designing, assembling and integrating the array sub-systems including the first-light beam combiner, the fringe tracker, the delay lines and carriages, an end-to-end vacuum beam transport system, an automated alignment system and all the control software infrastructure. Additionally we are working with subcontractors on several other major sub-systems including the unit telescopes and optics, the telescope enclosures, and the overall array infrastructure. This talk presents an overview of the design of the entire facility, discussions of innovative approaches on several subsystems, and a timeline toward first fringes and scientific commissioning of MROI. Delivery of the first telescope is anticipated in 2010, with first light anticipated in 2011.

IRAS 19190+1102: A New Water Fountain PPN

F. Day, Y. Pihlstrom (UNM), M.J. Claussen (NRAO) & R. Sahai (JPL/Caltech)

Water fountain pre-planetary nebulae (PPNs) are intermediate-mass stars undergoing a transition from the asymptotic giant branch (AGB) phase to becoming planetary nebulae (PPNs). These water fountain PPNs show high-velocity, collimated outflows that are indicative of the presence of jets. There exists only a handful of known water fountain PPNs, and in this talk we introduce the newest member of this class of objects--IRAS 19190+1102. We report on high resolution VLBA observations of H2O masers from jets in this dying star.

The New Zealand Cosmic Noise Expedition of 1948- Revisited

M. Goss (NRAO)

In the 24th New Mexico Symposium I described my 2008 trip to New Zealand to find the two sites of the Bolton Stanley 1948 expedition. They brought a 100 MHz gun laying radar set from Sydney to Auckland to use as a radio telescope in the sea cliff interferometer mode. Based on this data Taurus A was identified with the Crab Nebula; other identifications were made : Virgo A with M87, and Centaurus A with NGC 5128. In November 2009 I made returned visits to these sites. Now we have found the families who were the hosts of the Australian group in 1948; pictures and letters have been identified and we have now found the exact site of the radio telescopes on the east coast - Pakiri Hill near Leigh- and Piha on the west coast of the north Island within a 100 km of Auckland.

Studying Hybrid gamma Doradus/delta Scuti Variable Stars with Kepler

J. A. Guzik & the Kepler Asteroseismic Consortium Working Groups #4 and #10

In its search for earthlike planets, the NASA Kepler mission is observing thousands of stars with unprecedented photometric precision. Among these are main sequence gamma Doradus and delta Scuti variables. The gamma Dor stars pulsate in gravity modes with periods of about a day, while the delta Scuti stars pulsate in pressure modes with periods order two hours. Stars that are hybrids, i.e., pulsate in both types of modes simultaneously, would be especially useful to study the interior structure of these stars. We will discuss the theoretical predictions for hybrids, and first Kepler results on candidates found to date.

Exoplanetary Circumstellar Environments and Disk Explorer (EXCEDE): A new space telescope concept for NASA's Explorers Program.

D. Hines (Space Science Institute)

The Exoplanetary Circumstellar Environments and Disk Explorer (EXCEDE) will directly image material in the planet forming regions of stars exhibiting thermal-IR emission above their stellar photospheric levels (a signpost planetary system formation). EXCEDE will provide contrast-limited scattered-light detection sensitivities 100-1000 greater than the HST and JWST coronagraphs at smaller inner working angle, enabling the exploration and characterization of exoplanetary circumstellar disk systems in currently inaccessible observational domains. EXCEDE will also directly image and characterize extrasolar giant planets with orbital distances >1.5AU and disk substructures influenced by co-orbiting planets - for the first time within the terrestrial planet zone (< 5AU).

Estimating atmospheric dust contributions on Mars from laboratory studies of dust devils

L.D.V. Neakrase(Arizona State & NMSU) & Ronald Greeley(NMSU)

Recent laboratory work involved sediment fluxes for lab-scaled dust devils using the Arizona State University Vortex Generator. Sediment flux measurements were conducted using dust (< 63 µm) and sand (~90 to 2000 µm) with densities (1300 to 4800 kg m-3) at Earth-ambient (~1000 mbar) and Mars-analog (~10 mbar) atmospheric conditions. Flux was represented as a function of core pressure that could be compared to natural distributions on Mars to yield estimates of atmospheric dust contributions. Resulting flux estimates yielded the highest values (~1 to 43 kg km-2 sol-1) with ranges depending on average sizes, activity duration, and surface roughness effects.

The VLBA Sensitivity Upgrade: Science and Status

J.D.Romney, J.S. Ulvestad, W.F. Brisken, R.C. Walker, & S.J. Durand (NRAO)

The VLBA Sensitivity Upgrade Project will yield a nearly sixfold increase in the sensitivity of continuum observations, the first significant increase since the instrument?s construction in the 1980s. Modern technology allows enhanced performance, flexibility, and compatibility to be achieved at relatively modest cost, expanding the simultaneously observable data path to accommodate the entire 500-MHz dual-polarization IF bandwidth. For 2-bit Nyquist sampling, this requires sustained recording at 4 Gbit/sec, a goal the project aims to achieve by 2011. This talk will highlight some of the most compelling scientific drivers, as well as the substantial progress achieved since the previous NM Symposium.

The massive red sequence of cluster galaxies at z~1.4

V. Strazzullo (NRAO), P. Rosati (ESO), M. Pannella (NRAO), C. Lidman (ESO), C. Mullis (Wachovia Corp.), R. Demarco (Concepción), R. Gobat (CEA Paris) & M. Nonino (INAF)

A clear red sequence is already in place in the color--magnitude diagram of massive galaxy clusters even earlier than redshift one. The very presence of this structure points toward an early evolution of massive cluster galaxies on a similar time scale. On the other hand, signatures of structural evolution of these same objects might indicate a more complex evolutionary path. Distant galaxy clusters provide a unique opportunity to observe these galaxies at a significant look-back time, and thus to set tighter constraints on massive galaxy evolution in overdense environments. I will focus on the red sequence in the massive X-ray luminous cluster XMMU J2235-2557 at z=1.39, one of the best observed systems among the handful of clusters in the z~1.5 redshift range.

Probing the TeV Emission and Jet Collimation Regions in M87

R.C. Walker (NRAO), M. Beilicke (Washington U.), F. Davies (NRAO and NMT ), P.E. Hardee (U. of Alabama ), H. Krawczynski (Washington U.), D. Mazin (Institut de Fisica d'Altes Energies), R. Wagner (MPIfP), M. Raue (MPIfK), S. Wagner (Landessternwarte Heidelberg), C. Ly (UCLA) & W. Junor (LANL)

M87 was monitored intensively in early 2008 using the imaging atmospheric Cerenkov telescopes (VERITAS, H.E.S.S. and MAGIC) and the VLBA. Flares stronger than any seen before were observed both at TeV energies and in the unresolved radio core at 43 GHz, with the TeV flares occuring near the time that the radio flux density started to rise. The results pinpoint the location of the TeV emission to within a few tens of Schwarzschild radii of the black hole - a many-orders-of-magnitude improvement over previous position determinations. These results, along with others from the VLBA monitoring project will be presented.


Dust in Intermediate Polars: Light Curves from the Spitzer Space Telescope

K.E. Belle (LANL), D.W. Hoard (SSC) & S.B. Howell (NOAO)

Our recent observations of cataclysmic variables (CVs) with the Spitzer Space Telescope have identified two modes of "dustiness": non-magnetic CVs have a large reservoir of dust located inside the binary, just beyond the outer edge of the optically visible accretion disk, while magnetic CVs have dust located outside of the binary. These results motivated us to add intermediate polars (IPs) to the list of CVs observed with Spitzer.

Here we present Spitzer 4.5 um light curves of two IPs and we compare these results with our previous observations of magnetic and non-magnetic systems.

The contribution of the DiFX software correlator to the VLBA sensitivity upgrade

A. Deller, W. Brisken, J. Romney & C. Walker (NRAO)

The VLBA sensitivity upgrade is an ambitious plan to triple the continuum sensitivity of the VLBA via a bandwidth expansion. Meeting this goal required replacing the original VLBA hardware correlator, which is based on 1980s technology and unable to process the wider bandwidths. The chosen replacement is DiFX, a flexible and powerful software correlator which entered production usage in 2009 as the first completed element of the sensitivity upgrade. In addition to facilitating the forthcoming bandwidth expansion, DiFX brings a host of new capabilities to enable exciting new science with the VLBA, including high spectral and temporal resolution analysis, widefield imaging, pulsar studies, and efficient wide area surveying.

Using Twisted Helices to Model the M87 Jet

J. Eilek (NMT/NRAO), P. Hardee (U. Alabama), A. Lobanov (MPIfR/Bonn) & F. Owen (NRAO).

The inner jet in M87 contains a twisted, double-helix structure. The helix wavelength increases going along the jet, at the same time as the jet flow speed declines. Such a structure is reminiscent of the elliptical surface mode of the Kelvin-Helmholtz instability. Our numerical models show that this instability can explain the observations, if the jet plasma is mildly relativistic and if the jet is immediately surrounded by a hot plasma sheath. We also simulate a pseudo-synchrotron radio image of the jet, including relativistic and orientation effects. We find that the modelled jet deceleration maintains approximately the right average surface brightness, but that the bright knots require {\it in situ} energization (possibly by low-Mach shocks). We speculate that the jet disruption past knots A/B is due to the helical mode of the same instability.

Microwave Observations of Neptune

B. Hesman (NRAO), M. Hofstadter (JPL), B. Butler (NRAO) & K. Devaraj (Georgia Tech)

Images of Neptune in the microwave are used to study the troposphere of this dynamic planet. VLA images at X, U, and K-band VLA have shown that Neptune's atmosphere has large mid-latitude dim regions and a bright pole. The dim regions indicate convective activity and the bright pole indicates a decreased amount of opacity from absorbers (NH3, H2S, and H2O). These observations will be presented.

NESSI: the New Mexico Tech Extrasolar Spectroscopic Survey Instrument

K. Houairi, C. Jurgenson, M. Creech-Eakman (NMT/MRO), G. Vasisht, M. Swain (NASA/JPL), F. Santoro (NMT/MRO), P. Deroo (NASA/JPL), P. Boston (NMT) & P. Chen (NASA/JPL)

Less than 20 years after the discovery of the first extrasolar planet, exoplanetology is rapidly growing with more than one discovery every week on average since 2007. An important step in exoplanetology is the chemical characterization of exoplanet atmospheres. It has recently been shown that molecular signatures of transiting exoplanets can be studied. To advance this idea and prepare more ambitious projects such as THESIS, a dedicated spectrometer named New Mexico Tech Extrasolar Spectroscopic Survey Instrument (NESSI) is being built at New Mexico Tech in collaboration with the NASA Jet Propulsion Lab. This paper focuses on the NESSI optical design.

Formation of Coronal Holes on Ashes of Decaying Active Regions

N. Karachik & A.A. Pevtsov (NSO)

We study formation of three coronal holes (CHs) during recent deep minimum of sunspot activity. Coronal holes have developed in unipolar areas of magnetic field which on previous solar rotations were part of bipolar active regions. In one case, the CH has developed in following polarity and two cases, CHs have formed in place of leading polarity of decaying regions. In all cases, coronal holes contain a significant fraction of active region magnetic field. Using potential field extrapolation we have found that magnetic field lines of these coronal holes were closed to polar coronal hole at solar North, which at the time of the events was in imbalance with the polar coronal hole at South pole. We discuss our findings in the framework of Babcock-Leighton phenomenological model of solar cycle.

The Arecibo L-Band Feed Array (ALFA) Zone of Avoidance Survey

T. McIntyre, P.A. Henning (UNM) & R. Minchin (Arecibo, NAIC)

The ALFA Zone of Avoidance survey studies galaxies hidden behind the plane of the Milky Way by observing the 21cm line of neutral hydrogen (HI) using the Arecibo Radio Telescope. This survey will detect thousands of previously undiscovered galaxies in regions of the universe that have never been observed before. It will map the mass distribution of the local universe, uncover large scale structure, and contribute to the understanding of the HI mass function in the deepest, wide-angle HI survey ever conducted.

The LEAP of Pulsars in the Milky Way

M. McKinnon (NRAO)

The location of objects on the celestial sphere is a fundamental measurement in astronomy, and the distribution of these objects within the Milky Way is important for understanding their evolution as well as the large scale structure of the Galaxy. Here, physical concepts in Galactic astronomy are illustrated using straightforward mathematics and simplifying assumptions regarding the geometry of the Galaxy. Specifically, an analytical model for a smooth distribution of particles in an oblate ellipsoid is used to replicate the observed distributions of the Galactic coordinates for pulsars (PSRs) and supernova remnants (SNRs). The distributions and the Lambert equal area projections (LEAPs) of the coordinates suggest that the dominant factors determining the general shape of the distributions are the heavy concentration of objects in the Galactic Plane (GP) and the offset of the Galactic Center from the coordinate system origin. The LEAPs and the distributions also show that the dispersion of PSRs about and along the GP are much larger than that for SNRs. Additionally, the model can be used to derive an analytical expression for dispersion measure (DM) along any line of sight within the Galaxy. The expression is used to create a hypothetical DM-distance map for PSRs in the Galaxy.

Supernova 1987A Interpreted through the SLIP Model

J. Middleditch (LANL)

The model of superluminally induced polariation currents is used to explain the very early phenomena observed from SN 1987A. The central 2.14 ms pulsar literally eviscerated ~10 solar masses of ejecta, forcing the remnant into two high velocity jets (0.95 c), and a toroidal equatorial component. This applies to all SNe observed so far.

Analysis of Images from the Apache Point Observatory LCROSS Impact Observation Campaign

C. Miller, N.J. Chanover, R.T. Hamilton (NMSU), R.M. Suggs (NASA/MSFC) & R.J. McMillan (APO).

The 2009 LCROSS impact in Cabeus crater at the lunar south pole provided an opportunity to observe the ejecta plume from an impactor of known mass, velocity, and entry angle. We observed the LCROSS target with the 3.5 meter and 1.0 meter telescopes at Apache Point Observatory and the 0.6 meter telescope at Tortugas Mountain in Las Cruces. We discuss the challenges of observing a diffuse plume against the illuminated lunar limb. We also present images of Cabeus before and after impact and analyze these images for evidence of a faint plume. This work is supported by USRA grant number GR0002970.

VLA HI Imaging of HIPASS-Selected Early Type Galaxies

K. Nyland, L. Young, D. Lucero (NMT), R. Morganti (ASTRON) & E. Sadler (U. of Sydney)

We present the preliminary results of VLA HI imaging of a statistically well-defined sample of 35 HIPASS-selected early-type galaxies. Our sample compliments that of Oosterloo et al. 2006, which was heavily weighted towards lenticulars. This project aims to provide much needed statistical information regarding the properties of cold gas in elliptical galaxies, which will ultimately help constrain the general formation histories of elliptical vs. lenticular galaxies. Our results demonstrate that the HI morphologies of elliptical galaxies are varied - we find some regular, relaxed disks as well as disturbed, interacting systems with prominent features such as HI tidal tails.

HII Regions in the Outer Disk and Tidal Arms of M81

M.T. Patterson, R.A.M. Walterbos (NMSU), D.A. Thilker (Johns Hopkins), R.C. Kennicutt (Institute of Astronomy) & C. Chiappini (Geneva Observatory & INAF-OATrieste)

The outer disk spiral arms of M81 are fertile grounds for exploring star formation in low density environments. Much attention has focused on the evidence for star formation and on the properties of the stellar populations detected in the extended HI features. We report on a study of the HII region population around M81, derived from a Burrell Schmidt H-alpha composite supplemented with ARC 3.5-m emission line images. We discuss the luminosities and morphologies of the HII regions and compare the current massive star formation with the recent rates inferred from the stellar populations detected in the outer disk features.

A Spitzer Spectroscopic View of Gaseous Halos

Richard Rand (UNM), Robert A. Benjamin (U. of Wisconsin) & Kenny Wood (U. of St. Andrews)

We present Spitzer measurements of [Ne III]/[Ne II] in the halos of edge-on galaxies NGC 891, NGC 5775 and NGC 3044. In the first two galaxies, the neon ratio is higher in the halo than in the disk, presenting serious problems for photo-ionization models. Scale heights for 10-20 micron PAHs and HI are comparable. In NGC 891, the 8 micron scale height is lower, suggesting a drop in PAH ionization with height. Scatter confuses the situation in NGC 3044. For all three galaxies, most EWs are higher in the halos, suggesting a subtle change in the PAH population.

Quantitative Agreement of Pulsar Spectra with the Emission from a Rotating Faster-than-light Source Across Sixteen Orders of Magnitude

A. Schmidt (UNM/LANL), J. Singleton (LANL), H. Ardavan (Cambridge), J. Fasel (LANL), D. Bizzozero (UNM/LANL) & J. Middleditch (LANL)

We compare the multiwavelength observations of 9 broad-band pulsars (Crab, Vela, Geminga, B0656+14, B1055-52, B1509-58, B1706-44, B1929+10, and B1951+32) with the spectrum of the radiation generated by an extended polarization current whose distribution pattern rotates faster than light in vacuo and show that the entire spectrum of each pulsar can be accounted for quantitatively in terms of this single emission process.

The Winding HI Spiral Arms of the Barred Galaxy NGC 1365

J. Speights & D. Westpfahl (NMT)

We present a new method for solving the Tremaine-Weinberg equations for a pattern speed that is allowed to vary as a function of radius. The method transforms an integral equation for the pattern speed to a least squares problem with well established solution techniques and procedures for statistical analysis. It is exceptional for its ability to test whether the pattern speed is constant or if the spiral arms are winding - the former being a crucial assumption in density-wave theory. Tests of the method on patternless galaxies have produced a result of zero for the pattern speed. The method has been applied to the HI spiral arms of the barred grand-design spiral galaxy NGC 1365. Results for NGC 1365 show that the HI spiral arms more closely resemble material arms than a density wave with a constant pattern speed.

Dynamic screening in solar p-p reactions

K. Mussack (LANL)

Although the Salpeter approximation for static screening is widely accepted and used in stellar modeling, the question of dynamic screening has been revisited. Here we reproduce Shaviv and Shaviv's numerical analysis of the screening energy for p-p reactions in the solar core using the techniques of molecular dynamics to directly calculate the motion of ions and electrons due to Coulomb interactions without the mean-field assumption inherent in the Salpeter approximation. We conclude that the effects of dynamic screening are relevant and should be included in the treatment of the plasma, especially in the computation of nuclear reaction rates.

A Progress Report on the Long Wavelength Array

G.B. Taylor & J. Craig on behalf of the LWA Collaboration

The Long Wavelength Array (LWA), a SKA Pathfinder, will consist of 53 phased-array ?stations,? each consisting of 256 pairs of crossed-dipole antennas, operating with Galactic noise-limited sensitivity over the frequency range 20?80 MHz. The stations will be distributed over the state of New Mexico, which has a relatively benign RFI environment, with maximum baselines (distances between stations) of up to 400 km, and nominally 16 stations in a ?core? within the central 10 km. The LWA will form four independent (in both frequency and pointing) beams on the sky, with instantaneous bandwidths of 8 MHz per beam, spectral resolutions down to 100 Hz, and temporal resolutions to 0.1 ms. It will image wide fields of view with sufficient diversity of baselines to study both compact and complex sources in interferometric mode. The planned sensitivity in each beam will be a few mJy in 8 hours with a resolution of 8" to 2" (20 to 80 MHz).

The first LWA station is under construction, and should be operating with a partial digital system by February 2010, and in full operation by November 2010. In addition to verifying the technical design elements, LWA-1 will provide critical engineering studies that must be done before proceeding to the next stations. It will also host a number of scientific programs addressing pulsars, general transient searches, radio recombination lines, solar and Jupiter bursts, and ionospheric phenomena.

Polarization Properties of Active Galaxies on Parsec Scales

S.E. Trembla, G.B. Taylor, G.B. (UNM) & J.F. Helmboldt (NRL)

The VLBA Imaging and Polarimetry Survey (VIPS; Helmboldt et al. 2007) collected polarization data on a flux limited sample of 1119 sources. We have also obtained VLBA follow-up observations of a number of sources to clarify their morphological type and to obtain multi-frequency VLBI polarimetry. Here we present a preliminary statistical analysis on these data. As expected, core-jet sources are more likely to be polarized than Compact Symmetric Objects (CSOs) which are likely to be oriented closer to the plane of the sky, and are thus viewed through greater Faraday depths. However, since there exist CSOs with detected polarization, further work needs to be done to test and possibly expand this simple model.

Modeling Vertically Extdended Neutral Gas in the Edge-on Galaxy NGC4302

L.K. Zschaechner, R.J. Rand (UNM), R.A. Walterbos (NMSU) & R.A. Benjamin (U. of Wisconsin)

Recent realizations concerning kinematic measurements of gaseous halos in nearby galaxies may provide important clues to the origin of such halos and thereby the growth and evolution of galaxy disks. In particular, recent measurements have shown a decrease in rotation speed with height in a few halos, leading to various models which attempt to understand this gradient in terms of disk-halo flows and accretion of primordial gas. One observational issue is whether ionized and neutral halos show the same kinematics, suggesting a common origin or whether they diverge, leading to potentially different origins. The steepest gradient of rotation speed is -30 km/s/kpc in NGC 4302 (Heald et al. 2007), a galaxy with relatively weak star formation activity. Here we present deep VLA HI observations of this galaxy in the B and C configurations. From these observations, we clearly detect a vertically extended component. We present models showing whether the kinematics of this component are best represented by a flare, a warp along the line of sight, a lagging halo or a combination of the three. Due to asymmetries in the galaxy itself, these models vary somewhat between the approaching and receding halves. At this time we have successfully modeled a warp along the line of site and will have put constraints on any flare or lagging halo by January 15.

Last modified 2010 Jan 13 by Amy Mioduszewski.