Stars, Interstellar Medium and the Galaxy Commons^™

Back Half Of The Year, Ian R. Clarke

Physics and Astronomy Faculty Publications

Here we are in the back half of 2016, and the days are getting shorter. We have, as of today, lost 18 minutes since the solstice on June 20, and the speed of that change is quickening. You may wonder why it is that we have our hottest weather after our longest day is behind us. The simple answer is that it takes time for land and water masses to warm up. That’s the reason that Sept. 21 is likely to be a lot warmer than March 21, even though they have the same amount of daylight. [excerpt]

Living In The Milky Way, Ian R. Clarke

Physics and Astronomy Faculty Publications

It’s finally here. Today, June 20 at 6:34 p.m., is the the summer solstice, also known as the first day of summer and, confusingly enough, midsummer’s eve. From a scientific perspective, it marks the moment the sun reaches its northernmost point in our sky. As a result of that position, it’s the shortest night and longest day if you live north of the equator. [excerpt]

Peering Through The Dust: Nustar Observations Of Two First-2mass Red Quasars, Stephanie M. Lamassa, Angelo Ricarte, Eilat Glikman, C. Megan Urry, Daniel Stern, Tahir Yaqoob, George B. Lansbury, Francesca Civano

Dartmouth Scholarship

Some reddened quasars appear to be transitional objects in the merger-induced black hole growth/galaxy evolution paradigm, where a heavily obscured nucleus starts to be unveiled by powerful quasar winds evacuating the surrounding cocoon of dust and gas. Hard X-ray observations are able to peer through this gas and dust, revealing the properties of circumnuclear obscuration. Here, we present NuSTAR and XMM-Newton/Chandra observations of FIRST-2MASS selected red quasars F2M 0830+3759 and F2M 1227+3214. We find that though F2M 0830+3759 is moderately obscured (N_H,Z=2.1±0.2×10²² cm⁻²) and F2M 1227+3214 is mildly absorbed (N_H,Z=3.4+0.8−0.7×10²¹ cm^{−2 …}

Building A Scalable Global Data Processing Pipeline For Large Astronomical Photometric Datasets, Paul Doyle

Other

Astronomical photometry is the science of measuring the flux of a celestial object. Since its introduction, the CCD has been the principle method of measuring flux to calculate the apparent magnitude of an object. Each CCD image taken must go through a process of cleaning and calibration prior to its use. As the number of research telescopes increases the overall computing resources required for image processing also increases. Existing processing techniques are primarily sequential in nature, requiring increasingly powerful servers, faster disks and faster networks to process data. Existing High Performance Computing solutions involving high capacity data centres are complex …

Maximizing Precision Of Variable Star Photometry With Digital Cameras In Suburban Environments, David Hergesheimer

STAR Program Research Presentations

Photometry is the measure of the brightness of an object. When making such measurements on stars, it is done is units of magnitude, which is on a logarithmic scale with a base of ~2.512. Variable star photometry using a commercially available digital camera is not going to be as accurate and precise as equipment used by astronomers, and because of the logarithmic scale of magnitude used, determining how much of an effect different error reduction strategies have is not straightforward, and is best done experimentally.

My research is conducting photometry on variable stars (changing brightness) with a digital camera, and …

1207-3900_Nir_Spex, Jonathan Gagné

Publications and Research

No abstract provided.

1207-3900_Opt_Mage, Jonathan Gagné

Publications and Research

No abstract provided.

Book Review: Cosmic Dawn: The Search For The First Stars And Galaxies, T. D. Oswalt

Publications

This document is Dr. Oswalt’s review of Cosmic Dawn : the Search for the First Stars and Galaxies by George Rhee, springer, 2013. 279p, 9781461478126 $39.99, 9781461478133 $29.99.

Book Review: The Observer's Guide To Planetary Motion: Explaining The Cycles Of The Night Sky, T. D. Oswalt

Publications

This document is Dr. Oswalt’s review of The Observer's Guide to Planetary Motion : Explaining the Cycles of the Night Sky by Dominic Ford. Springer, 2014 240p index afp, 9781493906284 $34.99.

0112+1703_Nir_Gnirs, Michael C. Liu

Publications and Research

No abstract provided.

2114-2251_Nir_Gnirs, Michael C. Liu

Publications and Research

No abstract provided.

Optical And X-Ray Studies Of 10 X-Ray-Selected Cataclysmic Binaries, John R. Thorstensen, Jules Halpern

Dartmouth Scholarship

We report on ground-based optical observations of 10 cataclysmic binaries that were discovered through their X-ray emission. Time-resolved radial velocity spectroscopy yields unambiguous orbital periods for eight objects and ambiguous results for the remaining two. The orbital periods range from 87 minutes to 9.38 hr. We also obtained time-series optical photometry for six targets, four of which have coherent pulsations. These periods are 1218 s for 1RXS J045707.4+452751, 628 s for AX J1740.2–2903, 477 s for AX J1853.3–0128, and 935 s for IGR J19267+1325. A total of seven of the sources have coherent oscillations in X-rays or optical, indicating that …

Analyzing The Performance Of The Sofia Infrared Telescope, Sarah M. Bass, Jeffrey Van Cleve, Zaheer Ali

STAR Program Research Presentations

The Stratospheric Observatory for Infrared Astronomy (SOFIA) is an airborne near-space observatory onboard a modified Boeing 747-SP aircraft, which flies at altitudes of 45,000 ft., above 99% of the Earth’s water vapor. SOFIA contains an effective 2.5 m infrared (IR) telescope that has a dichroic tertiary mirror, reflecting IR and visible wavelengths to the science instrument (SI) and focal plane imager (FPI), respectively. To date, seven different SIs have been designed to cover a wide range of wavelengths and spectral resolutions. Since the telescope operates in the infrared, different techniques, including chopping, nodding, and dithering, are used to reduce the …

Astronomy / Galactic Structure - Rensselaer Polytechnic Institute, Kathryn M. Dunn

Data Curation Profiles Directory

The researcher participates in large-scale astronomical survey projects, which are collaborative efforts of many institutions and individuals. Management of the raw and processed/calibrated data is handled by those projects, but data for specific research questions is handled by the researcher. The researcher would like to have a better way to share the data behind the figures in their published papers with other researchers. The effort involved in retrieving and documenting the data so it’s usable by others is a barrier to sharing the data. It would be easier to share data from publications if it could be deposited to a …

The Interior Structure Constants As An Age Diagnostic For Low-Mass, Pre-Main-Sequence Detached Eclipsing Binary Stars, Gregory A. Feiden, Aaron Dotter

Dartmouth Scholarship

We propose a novel method for determining the ages of low-mass, pre-main-sequence stellar systems using the apsidal motion of low-mass detached eclipsing binaries. The apsidal motion of a binary system with an eccentric orbit provides information regarding the interior structure constants of the individual stars. These constants are related to the normalized stellar interior density distribution and can be extracted from the predictions of stellar evolution models. We demonstrate that low-mass, pre-main-sequence stars undergoing radiative core contraction display rapidly changing interior structure constants (greater than 5% per 10 Myr) that, when combined with observational determinations of the interior structure constants …

Contellation: Taurus, Gabriel Chaille

Natural Sciences Student Research Presentations

Using the constellation Taurus, the purpose of this project was to gain insight on how information is gathered about stars and what purpose that information serves.

Supernova Resonance-Scattering Line Profiles In The Absence Of A Photosphere, Brian Friesen, E. Baron, David Branch, Bin Chen, Jerod T. Parrent, R. C. Thomas

Dartmouth Scholarship

In supernova (SN) spectroscopy relatively little attention has been given to the properties of optically thick spectral lines in epochs following the photosphere's recession. Most treatments and analyses of post-photospheric optical spectra of SNe assume that forbidden-line emission comprises most if not all spectral features. However, evidence exists that suggests that some spectra exhibit line profiles formed via optically thick resonance-scattering even months or years after the SN explosion. To explore this possibility, we present a geometrical approach to SN spectrum formation based on the "Elementary Supernova" model, wherein we investigate the characteristics of resonance-scattering in optically thick lines while …

High-Velocity Outflows Without Agn Feedback: Eddington-Limited Star Formation In Compact Massive Galaxies, Aleksandar M. Diamond-Stanic, John Moustakas, Christy A. Tremonti, Alison L. Coil, Ryan C. Hickox

Dartmouth Scholarship

We present the discovery of compact, obscured star formation in galaxies at z ~ 0.6 that exhibit 1000 km s^–1 outflows. Using optical morphologies from the Hubble Space Telescope and infrared photometry from the Wide-field Infrared Survey Explorer, we estimate star formation rate (SFR) surface densities that approach Σ_SFR ≈ 3000 M _☉ yr^–1 kpc^–2, comparable to the Eddington limit from radiation pressure on dust grains. We argue that feedback associated with a compact starburst in the form of radiation pressure from massive stars and ram pressure from supernovae and stellar winds is sufficient …

Telescope Assembly Alignment Simulator Performance Optimization, Joshua G. Thompson, Brian Eney, Zaheer Ali, Bob Thompson

STAR Program Research Presentations

The Telescope Assembly Alignment Simulator (TAAS) calibrates scientific instruments (SI’s) that are installed on the Stratospheric Observatory For Infrared Astronomy (SOFIA). An SI’s accuracy is directly dependent on the consistent performance of the TAAS, which has never been fully characterized. After designing various thermal and optical experiments to identify the current unknowns of TAAS, we now have a far better grasp on how the equipment behaves.

Analysis Of The Early-Time Optical Spectra Of Sn 2011fe In M101, J. T. Parrent, D. A. Howell, B. Friesen, R. C. Thomas

Dartmouth Scholarship

The nearby Type Ia supernova SN 2011fe in M101 (cz=241 km s^-1) provides a unique opportunity to study the early evolution of a "normal" Type Ia supernova, its compositional structure, and its elusive progenitor system. We present 18 high signal-to-noise spectra of SN 2011fe during its first month beginning 1.2 days post-explosion and with an average cadence of 1.8 days. This gives a clear picture of how various line-forming species are distributed within the outer layers of the ejecta, including that of unburned material (C+O). We follow the evolution of C II absorption features until they diminish near maximum light, …

Late-Time Optical Emission From Core-Collapse Supernovae, Dan Milisavljevic, Robert A. Fesen, Roger A. Chevalier, Robert P. Kirshner

Dartmouth Scholarship

Ground-based optical spectra and Hubble Space Telescope images of 10 core-collapse supernovae (CCSNe) obtained several years to decades after outburst are analyzed with the aim of understanding the general properties of their late-time emissions. New observations of SN 1957D, 1970G, 1980K, and 1993J are included as part of the study. Blueshifted line emissions in oxygen and/or hydrogen with conspicuous line substructure are a common and long-lasting phenomenon in the late-time spectra. Followed through multiple epochs, changes in the relative strengths and velocity widths of the emission lines are consistent with expectations for emissions produced by interaction between SN ejecta and …

1112+3548_Nir_Spex, J. Patience

Publications and Research

No abstract provided.

The Sn 393-Snr Rx J1713.7-3946 (G347.3-0.5) Connection, Robert A. Fesen, Richard Kremer, Daniel Patnaude, Dan Milisavljevic

Dartmouth Scholarship

Although the connection of the Chinese "guest" star of 393 AD with the Galactic supernova remnant RX J1713.7-3946 (G347.3-0.5) made by Wang et al. in 1997 is consistent with the remnant's relatively young properties and the guest star's projected position within the "tail" of the constellation Scorpius, there are difficulties with such an association. The brief Chinese texts concerning the 393 AD guest star make no comment about its apparent brightness, stating only that it disappeared after eight months. However, at the remnant's current estimated 1-1.3 kpc distance and A _V 3, its supernova (SN) should have been a visually …

Book Review: Clocks In The Sky: The Story Of Pulsars, T. D. Oswalt

Publications

This document is Dr. Oswalt’s review of Clocks in the Sky: The Story of Pulsars by Geoff McNamara, Springer/Praxis, 2008 190p, 9780387765600 $29.95.

General Search For Stars With Rapid Optical Variations: Test Fields, Elizabeth Fagg, Jieun Park, Kelly Pearson, Robert Kehoe

Journal of Undergraduate Research

We present a search for stars exhibiting short time-scale optical lightvariations. Our search employs archival data taken by the ROTSE1 telephotoarray in two eight degree fields of view. This is a test study considering two fields which overlap fields previously mined for variables, but with different dataand search techniques. Each field was observed for approximately six continuous hours. We employ a general search strategy based on statistical properties of theobserved light curves for each object. The analysis is sensitive to sources with variations < 0.25 day and > 0.1 mag and with mean magnitudes between 9.5 magand 14 mag. We identify 42 variable stars with …

Statistical Analysis Of Stellar Evolution, David A. Van Dyk, Ted Von Hippel, Steven Degenarro, Nathan Stein, William Jefferys

Publications

Color-Magnitude Diagrams (CMDs) are plots that compare the magnitudes (luminosities) of stars in different wavelengths of light (colors). High nonlinear correlations among the mass, color, and surface temperature of newly formed stars induce a long narrow curved point cloud in a CMD known as the main sequence. Aging stars form new CMD groups of red giants and white dwarfs. The physical processes that govern this evolution can be described with mathematical models and explored using complex computer models. These calculations are designed to predict the plotted magnitudes as a function of parameters of scientific interest, such as stellar age, mass, …

Book Review: Guide To Observing Deep-Sky Objects: A Complete Global Resource For Astronomers, T. D. Oswalt

Publications

This document is Dr. Oswalt’s review of Guide to Observing Deep-Sky Objects : a Complete Global Resource for Astronomers by Jeff A. Farinacci. Springer, 2007 189p, 9780387728506 $29.95

1139-3159_Nir_Spex, Dagny L. Looper

Publications and Research

No abstract provided.

1021-0304_Mir_Irs, Michael C. Cushing

Publications and Research

No abstract provided.

Stargazing: Observatories At Gettysburg College, 1874-Present, Andrew A. Carlson

Hidden in Plain Sight Projects

Astronomy has long been a subject which has attracted the interest of man. Examples of early astronomers can be found in many ancient civilizations, including but not limited to, the Egyptians, the Chinese and the Greeks. As time passed the methods for interpreting the stars and theories that surrounded them changed concordant with the technology available. One of the largest breakthroughs in the world of astronomy was the invention of the telescope in the early seventeenth century. Often mis-attributed to Galileo (who was responsible for building the first reflecting telescope in 1688), the telescope was actually first designed by a …