Aavso paper Session I sunday Sunday, May 22, 2011, 9: 30 am – 12: 00 pm

127

Supernovae. Planetary Nebulae, Evolved Stars, Cataclysmic Variables, Novae

Poster Session

Essex Ballroom

127.01

8:00 AM - 7:00 PM

In order to prepare students in grades 4-12 for a global workforce, NASA supports science, technology, engineering, and math (STEM) immersion education for secondary students. Secondary schools, through the NASA Explorer School program, the Spitzer Space Telescope, the National Optical Astronomy Observatory, and the WISE (Wide Field Infrared Survey Explorer) Telescope Teacher Ambassador program, offer authentic research opportunities for students. Spitzer and WISE studied the sky in infrared light. Among the objects WISE studied are asteroids, the coolest and dimmest stars, and the most luminous galaxies. The lessons learned from the NASA Explorer School program and Spitzer and WISE teacher and student programs can be applied to other programs, engaging students in authentic research experiences by using data from space-borne and earth-based observatories such Kitt Peak Observatory. Several ground based telescopes at Kitt Peak Observatory study visible light from objects such as supernovae. Utilizing a student research immersion philosophy along with data analysis skills learned from the Spitzer and WISE student research programs, an analysis of supernovae distribution with respect to location in the Andromeda galaxy was conducted using images of the Andromeda galaxy taken from the WIYN 0.9 meter telescope on Kitt Peak. A comparison was made between the 12 outer fields (spiral arms) and the 4 inner fields (central bulge). Novae were found by “blinking” images of each field throughout 100 epochs of data. Blinking is a technique used to compare images of fields and noting brightness (via x,y coordinates) in one field that is not visible in the same field during a different epoch. Although the central bulge was expected to contain more supernovae due to stellar density and proximity of stars to each other, analysis of data indicates that the there is also a concentration of supernovae that appeared in outer regions. WISE Telescope funding is gratefully acknowledged.

127.02

8:00 AM - 7:00 PM

Constraining Explosion Date and Progenitor Properties of SN 1998S with Early Photometry

8:00 AM - 7:00 PM

A core-collapse supernova (SN) would produce an expanding shell of charged particles which interact with the surrounding magnetic field of the progenitor star producing a transient radio pulse. Approximately one supernova event per century is expected in a galaxy. The radio waves emitted are detectable by a new generation of low-frequency radio telescope arrays. We present details of an ongoing search for such events by the Eight-meter-wavelength Transient Array (ETA) and the Long Wavelength Array (LWA).

127.04

Late Phase Light Curves of SN 2005hk

Jessica Crist Lair¹, P. Milne², G. Bryngelson³, M. Leising^3
1Eastern Kentucky Univ., ²Steward Observatory, ³Clemson University.

8:00 AM - 7:00 PM

Understanding the light curves of Type Ia Supernovae (SNe Ia) is essential to their use as standard candles in cosmological studies. Recent observations of SNe Ia have shown brighter than expected NIR emission at very late phases resulting in brighter than expected bolometric luminosity at that epoch. Also, some observations showed that the optical bands at very late phases were brighter than expected relative to the 200-330 day slope. Further study of these objects in both the optical and NIR bands is needed to better understand their behavior. We present the optical and NIR late phase light curves of the peculiar SN 2005hk as a tool to probe these questions.

127.05
Pulsar-driven Jets In Sne, Grbs, Lmxbs, Ss 433, And The Universe
John Middleditch^1
1LANL.
8:00 AM - 7:00 PM
Essex Ballroom
The model of pulsar emission through superluminally induced polarization currents, (SLIP), predicts that pulsations produced by such currents at many light cylinder radii by a rotating, magnetized body, will drive pulsations close to the axis of rotation. In SN 1987A, the possible Rosetta Stone for 99% of SNe, GRBs, ms pulsars, and SS 433, such highly collimated (<1 in 10,000) 2.14 ms pulsations, and the similarly collimated jets of particles which they drove, including 1e-6 solar masses with velocities ~0.95 c, were responsible for its very early light curve (days 3-20), its "Mystery Spot," observed slightly later (0.5 to 0.3 c, at days 30-50 and after), and still later, in less collimated form, its bipolarity. The axially driven pulsations enforce a toroidal geometry onto all early SNRs, rendering even SNe Ia unsuitable as standard candles. The numbers for Sco X-1's jet are identical, while those for SS 433 are lower (0.26 c), because of the absence of velocity "boosting" via collisions of heavy elements with lighter ones, due to the nearly pure hydrogen content of the supercritical accretion. SLIP also drives positrons from SNe to high energies, possibly accounting for the excess seen by PAMELA at scores of GeV, and predicts that almost all pulsars with very sharp single pulses have been detected because the Earth is in a favored direction where their fluxes diminish only as 1/distance, and this has been verified in the laboratory as well as for the Parkes Multibeam Survey. SLIP also predicts that GRB afterglows will be 100% pulsed at 500 Hz in their proper frame. Finally, SLIP jets from SNe of the first stars may allow galaxies to form without the need for dark matter. This work was supported in part by the Department of Energy through the Los Alamos Directed Research Grant DR20080085.

127.06

8:00 AM - 7:00 PM

Krisciunas et al. (2011) recently presented optical and near-IR photometry, plus many optical spectra of the Type Ia SN 2001ay. Its decline rate parameter dm15(B) = 0.68 mag, making it the most slowly declining Type Ia SN known to date. This object was not overluminous in optical bands, and was

127.07

8:00 AM - 7:00 PM

A critical component behind a supernova explosion is the spherical accretion shock instability, or SASI. Two theories describing this mechanism exist. An advective-acoustic mechanism says that entropy perturbations generated at the shock travel inward with the accretion flow at the free-fall velocity, which couple to an acoustic wave. If these perturbations amplify, the advective and acoustic waves lead to an instability. The acoustic theory states that the SASI is purely an acoustic phenomenon in which a sound wave travels around the circumference of the shock. This project attempts to resolve the debate between the two theories by observing the SASI in a regime where the timescales become disparate. Because the sound speed behind the shock is determined by the gravitational potential and the post shock flow speed is a strong function of the ratio of specific heats, gamma, the advective-acoustic mechanism has a much longer timescale for small values of gamma. We find that the timescales become highly disparate when gamma equals 1.2 and use two-dimensional simulations when gamma is 1.2 to quantify the growth rate of the instability. This will allow us to determine whether the SASI operates as an advective-acoustic or purely acoustic phenomenon.

127.08

High-Velocity Ca II in Type Ia Supernovae

G. H. Marion^1
1Harvard - CfA.

8:00 AM - 7:00 PM

We investigate the behavior of high-velocity (HV) Ca II absorption features in spectra of Type Ia supernovae (SNe Ia). HV features are found at velocities that are several thousand kilometers per second greater than typical photospheric (PS) velocities. We present data obtained between -14d and +1d and explore similarities and differences in the velocities and line profiles for features from the Ca II H&K lines and the Ca II Infrared Triplet (IR3). The evolution of HV Ca II is revealed in spectral series obtained from individual SNe Ia and these data are compared to spectra from more than 20 additional SNe Ia. HV Ca II appears in nearly all spectra obtained earlier than -5d, but we demonstrate that there are exceptions in which HV features are not detected. We also explore diversity in HV Ca II features from SNe Ia observed at the same epochs and the behavior of HV Ca II is compared to that of other spectral features and to light curve parameters.

127.09

Classification and Redshift Determination of Pan-STARRS Supernovae with Optical Cross Correlation Filters

Daniel Scolnic¹, A. Riess¹, M. Huber¹, S. Rodney¹, J. Tonry², PS1 Science Consortium
¹Johns Hopkins University, ²University of Hawaii.

8:00 AM - 7:00 PM

127.10

8:00 AM - 7:00 PM

We are undertaking a survey to establish an upper limit on the space density of cataclysmic variables (CVs) and related objects in the solar neighborhood through a proper-motion based approach. We start with the new Lépine-Shara proper motion survey, which is sensitive down to 40 mas/yr, and select CV candidates from this using NUV - V colors from GALEX and V - K colors from 2MASS. In our first exploratory spectroscopic run, using the 2.4m Hiltner telescope at MDM Observatory, we identified a single new CV, LSPM 03338+3320 In this presentation we give details on this new CV. Briefly, its orbital period is near 96 minutes, its spectrum shows the double-peaked Balmer emission lines characteristic of quiescent dwarf novae, and its V magnitude is near 18.2.

127.11

The Unusually Luminous Extragalactic Nova SN 2010U

Ian Czekala¹, R. Chornock¹, E. Berger¹, A. Pastorello², G. H. Marion³, P. Challis¹, J. C. Wheeler⁴, M. T. Botticella², S. Smartt², M. Ergon⁵, J. Sollerman^5
1Harvard University, ²Queen's University Belfast, United Kingdom, ³Harvard University/UT Austin, ⁴UT Austin, ⁵Stockholm University, Sweden.

8:00 AM - 7:00 PM

With the rise of time-domain astronomy and the advent of survey facilities such as Pan-STARRS, Palomar Transient Factory, and, in the future, LSST, exotic optical transients are now being found in ever-increasing numbers. These events can be distinct from the traditional categories of novae and supernovae, which are typically clustered around -8 and -18 absolute magnitudes, respectively. Objects intermediate in luminosity have been broadly labeled "supernovae imposters" because although the objects are initially bright enough to be classified as supernovae, upon further spectral analysis they mainly turn out to be luminous blue variables (LBVs). SN 2010U is one such supernovae impostor that is in fact a fast and luminous extragalactic nova (Humphreys et al. 2010). We present an early-time spectrum of SN 2010U two days after discovery that clearly identifies SN 2010U as an Fe II-type nova. Additionally, we present a complete r-band lightcurve that confirms that SN 2010U was a very fast and bright nova with absolute magnitude in excess of -10. The discovery of this exotic nova has implications for the mass of the white dwarf progenitor, accreted material, and theoretical brightness relations such as the maximum-magnitude versus rate of decline (MMRD) relationship. The supernova imposter SN 2010U probes a new phase space of transient phenomenon.

127.12

High Velocity Precessing Jet from the Water Fountain IRAS 18286-0959 Revealed by VLBA Observations

Bosco Yung¹, J. Nakashima¹, H. Imai², S. Deguchi³, P. J. Diamond⁴, S. Kwok^1
1The University of Hong Kong, Hong Kong, ²Kagoshima University, Japan, ³Nobeyama Radio Observatory, Japan, ⁴CSIRO Astronomy and Space Science, Australia.

8:00 AM - 7:00 PM

We report the multi-epoch VLBA observations of 22.2GHz water maser emission associated with the "water fountain" star IRAS 18286-0959. The detected maser emission are distributed in the velocity range from -50km/s to 150km/s. The spatial distribution of over 70% of the identified maser features is found to be highly collimated along a spiral jet (namely, jet 1) extended from southeast to northwest direction, and the rest of the features appear to trace another spiral jet (jet 2) with a different orientation. The two jets form a "double-helix" pattern which lies across ~200 milliarcseconds (mas). The maser features are reasonably fit by a model consisting of two precessing jets. The velocities of jet 1 and jet 2 are derived to be 138km/s and 99km/s, respectively. The precession period of jet 1 is about 56 years, and for jet 2 it is about 73 years. We propose that the appearance of two jets observed are the result of a single driving source with a significant proper motion. This research was supported by grants from the Research Grants Council of the Hong Kong Special Administrative Region, China, the Seed Funding Programme for Basic Research of the University of Hong Kong, Grant-in-Aid for Young Scientists from the Ministry 9 of Education, Culture, Sports, Science, and Technology, and Grant-in-Aid for Scientific Research from Japan Society for Promotion Science.

127.13

Time-resolved Optical Spectroscopy of the Classical Nova V723 Cas

Thomas Vonderharr¹, C. E. Woodward¹, R. M. Wagner², G. Schwarz³, L. A. Helton⁴, C. Hamilton-Drager⁵, K. A. Recine^5
1University of Minnesota, ²Large Binocular Telescope Observatory, ³American Astronomical Society (Corporate Offices), ⁴Stratospheric Observatory for Infrared Astronomy, ⁵Dickinson College.

8:00 AM - 7:00 PM

We present the results of time-resolved optical spectroscopy of the classical nova and super-soft X-ray source V723 Cas (Nova Cas 1995). The spectra were obtained at the Steward Observatory Bok 2.3-m telescope (range: 4180-5320 Angstroms) on Kitt Peak and at the MDM Observatory Hilter 2.4-m telescope (range: 4000-7500 Angstroms) in 2007, 2008, and 2010. Both sets of spectra were obtained at a spectral resolution of about 2 Angstroms. Exposure times of the individual spectra were about 20 minutes which is short compared to the 16.6-hour binary orbital period, thus minimizing velocity smearing of spectral features. V723 Cas is an unusual system, being an active super-soft X-ray source for more than 15 years since the 1995 outburst, in contrast to the median X-ray turn off time of only 1.4 years. This may be indicative of steady hydrogen burning on the white dwarf due to renewed accretion (Ness et al. 2008, AJ, 135, 1328). Phasing the individual spectra to the 16.6-hour binary photometric orbital period (Goranskij et al. 2007, Ast. Bull. 62, 125), we find that the Balmer emission lines exhibit a double-peaked accretion disk line profile convolved with a variable Gaussian emission line S-wave component. The He II 4686 emission line exhibits phase-dependent line profile variations as well. We have modeled both emission line profiles with a double-peaked accretion disk line component assuming different disk properties and an independent Gaussian component. The results of our line profile modeling compared to the orbital photometric behavior of V723 Cas are presented and we discuss the interpretation of our synoptic observations in the context of the post-outburst evolution of super-soft X-ray sources and this unusual classical nova.

127.14

Analysis of the High Dispersion Spectra of the Planetary Nebula NGC 7027

Siek Hyung¹, S. Lee¹, M. Otsuka², A. Tajitsu^3
1ChungBuk National Univ., Korea, Republic of, ²Space Telescope Science Institute, ³Subaru Telescope.

8:00 AM - 7:00 PM

Using the high dispersion spectra taken with the Keck I HIRES in 1998 August 13 - 15, we analyzed the electron density and electron temperature variation of the nebular gas shell of the planetary nebula NGC 7027. The employed slit dimensions and the observed wavelength regions are the following four settings: 1) 14" x 0.862" (8530 - 6309A; red collimator); 2) 10" x 0.862" (5130 - 7475A; red collimator); 3) 7" x 0.862" (3100 - 4100A; red collimator); and 4) 3.5" x 0.862" (3450 - 5900A; blue collimator). Since these employed slit lengths were shorter than the dimension of NGC 7027, we shifted the slit entrance of the HIRES on a nebular image and obtained various diagnostic spectral lines from the major and minor axes of the nebula. Many diagnostic lines, such as [N II]5755, 6583; [O III]4363, 4959+5007; [O II]3726, 3729; and [Ar IV]4711, 4740 that were useful in finding the physical conditions, were obtained. We present the line ratios and the anlayzed physical conditions in the main shell of the nebula that show some variation; log N_e = 4.25 - 4.75 cm^-3 ([S II], [Cl III], & [Ar IV]) and T_e = 13000 - 18000 K ([O III]). Although the analysis shows fluctuations in the physical condition, we postpone any conclusion on the existence of fine-structures in the main shell, responsible for high-density or high electron temperature components.

127.15

The Symbiotic Nature of M2-9

Jerica M. Green¹, B. Balick¹, J. Lutz^1
1University of Washington.

8:00 AM - 7:00 PM

We present moderate resolution deep stellar spectra of the object Minkowski 2-9 (M2-9) also known as the "Butterfly" or the Twin-Jet Nebula. M2-9's central star has been identified as a symbiotic star because bright H-alpha and weaker [NII] emission lines have been seen in its spectra, and its near infrared flux is more similar to symbiotic stars than planetary nebulae. Our calibrated and extracted spectra show that the star has dozens of faint emission lines, and those lines probably arise in a very dense circumstellar envelope. We compare the features from the central star of M2-9 to some well-known symbiotic stars.

127.16

Properties and Spatial Distribution of Dust Emission in the Crab Nebula

Tea Temim¹, G. Sonneborn², E. Dwek², R. G. Arendt³, R. D. Gehrz⁴, P. O. Slane^5
1NASA/GSFC/ORAU, ²NASA/GSFC, ³CRESST/UMBC, ⁴Univ. of Minnesota, ⁵Harvard-Smithsonian, CfA.

8:00 AM - 7:00 PM

The nature and quantity of dust produced in supernovae (SNe) is still not understood. Recent infrared (IR) observations of freshly-formed dust in supernova remnants (SNRs) have yielded significantly lower dust masses than predicted by theoretical models and high redshift observations. The Crab Nebula's pulsar wind is thought to be sweeping up freshly-formed SN dust along with the SN ejecta. The evidence for this dust was found in the form of an IR bump in the integrated spectrum of the Crab and in extinction against the synchrotron nebula that revealed the presence of dust in the filament cores. We present the first spatially resolved emission spectra of dust in the Crab Nebula acquired with the Spitzer Space Telescope. The IR spectra are dominated by synchrotron emission and show forbidden line emission from both sides of the expanding nebula, including emission from S, Si, Ne, Ar, Fe, and Ni. We extrapolated a synchrotron spectral cube from the Spitzer 3.6 and 4.5 micron images, and subtracted this contribution from our spectral data to produce a map of the residual continuum emission from dust. The emission appears to be concentrated along the ejecta filaments and is well fitted by astronomical silicates at an average temperature of 52 K. We discuss the spatial variations in the dust spectrum across the nebula and revise the total dust mass estimates.

127.17

Extending The Sma Spectral-line Survey Of Irc+10216 In The 400 Ghz Band

Nimesh A. Patel¹, K. Young¹, C. Gottlieb¹, P. Thaddeus¹, K. Menten², M. McCarthy¹, E. Keto¹, R. Wilson^1
1Harvard-Smithsonian Center for Astrophysics, ²Max Planck Institute for Radio Astronomy, Germany.

8:00 AM - 7:00 PM

Interstellar dust grains are thought to evolve in the colder regions of space from the gas and solids there, material believed to come from Asymptotic Giant Branch (AGB) stars. IRC+10216 is a well studied such star with high mass loss. Close to the Sun (~150 pc), it is an ideal place to study the physical and chemical processes in AGB circumstellar envelopes. Using the Submillimeter Array (SMA), we recently carried out the first interferometric spectral line-survey of IRC+10216 in the 345 GHz band, with an angular resolution of 3"x2". This survey has led to the discovery of many narrow lines of molecular emission, implying expansion velocities of ~4 km/s (in contrast with the typical value of the expansion velocity of 14.5 km/s known from previous surveys). Maps of these lines show that they are produced in the inner envelope, within 60 AU of the star, where the stellar wind is still being accelerated. Following this line survey in the 294-355 GHz frequency range, we are now extending the frequency coverage to 396-420 GHz. We will add higher frequency transitions for several molecules that were detected in our 345 GHz line survey, allowing us to better characterize the physical conditions in the inner circumstellar envelope. We will be able to derive abundances of several molecular species, for comparison with chemical models. Continuum fluxes at higher frequencies will help constrain the SED due to dust emission. These observations partially fill the gap between our previous survey (379-355 GHz) and the recently published survey at even higher frequencies (490-1900 GHz) with the Herschel HIFI. The SMA is a joint collaboration between the Smithsonian Astrophysical Observatory and the Academia Sinica Institute of Astronomy and Astrophysics.