Astrophysics and Astronomy Commons^™

Modeling The Light Curves Of The Luminous Type Ic Supernova 2007d, Shan-Qin Wang, Zach Cano, Long Li, Liang-Duan Liu, Ling-Jun Wang, Weikang Zheng, Zi-Gao Dai, En-Wei Liang, Alexei V. Filippenko

Physics & Astronomy Faculty Research

SN 2007D is a nearby (redshift z = 0.023146), luminous Type Ic supernova (SN) having a narrow light curve (LC) and high peak luminosity. Previous research based on the assumption that it was powered by the 56Ni cascade decay suggested that the inferred 56Ni mass and the ejecta mass are ~1.5 M ⊙ and ~3.5 M ⊙, respectively. In this paper, we employ some multiband LC models to model the R-band LC and the color (V − R) evolution of SN 2007D to investigate the possible energy sources powering them. We find that the pure 56Ni model is disfavored; the …

Real-Time Rfi Mitigation In Radio Astronomy, Emily Ramey, Nick Joslyn, Richard Prestage, Michael Lam, Luke Hawkins, Tim Blattner, Mark Whitehead

Senior Honors Papers / Undergraduate Theses

As the use of wireless technology has increased around the world, Radio Frequency Interference (RFI) has become more and more of a problem for radio astronomers. Preventative measures exist to limit the presence of RFI, and programs exist to remove it from saved data, but the use of algorithms to detect and remove RFI as an observation is occurring is much less common. Such a method would be incredibly useful for observations in which the data must undergo several rounds of processing before being saved, as in pulsar timing studies. Strategies for real-time mitigation have been discussed and tested with …

Arecibo Message, Joshua P. Tan

Open Educational Resources

This two week assignment asks students to interpret and analyze the 1974 Arecibo Message sent by Drake and Sagan. Week 1 introduces the concepts behind the construction of the message and engages with a critical analysis of the architecture and the contents of the message. Week 2 asks students to develop software in a Jupyter Notebook (available for free from the Anaconda Python Distribution) to interpret messages that were similar to those produced by Drake and Sagan.

Relativistic Astronomy. Ii. In-Flight Solution Of Motion And Test Of Special Relativity Light Aberration, Jin-Ping Zhu, Bing Zhang, Yuan-Pei Yang

Physics & Astronomy Faculty Research

The Breakthrough Starshot project aims to send centimeter-sized, gram-scale "StarChip" probes to Alpha Centauri at a speed of ~0.2 c. On the other hand, Zhang & Li recently proposed that transrelativistic cameras may be sent to any direction to study astronomical objects and test special relativity. To conduct such "relativistic astronomy," one needs to solve the motion of the probe in flight. We solve the motion of the probe (including the moving direction and the velocity) by comparing the positions of three or more point sources observed in the Earth rest frame and in the probe's comoving frame. When the …

Cosmology-Independent Estimate Of The Fraction Of Baryon Mass In The Igm From Fast Radio Burst Observations, Zhengxiang Li, He Gao, Jun-Jie Wei, Yuan-Pei Yang, Bing Zhang, Zong-Hong Zhu

Physics & Astronomy Faculty Research

The excessive dispersion measure (DM) of fast radio bursts (FRBs) has been proposed to be a powerful tool to study intergalactic medium (IGM) and to perform cosmography. One issue is that the fraction of baryons in the IGM, f IGM, is not properly constrained. Here, we propose a method of estimating f IGM using a putative sample of FRBs with the measurements of both DM and luminosity distance d L. The latter can be obtained if the FRB is associated with a distance indicator (e.g., a gamma-ray burst or a gravitational-wave event), or the redshift z of the FRB is …

Haro 11, Pox 186, And Vcc 1313: The Enigmatic Behavior Of Hi Non-Emitters, Sarah H. Taft

Macalester Journal of Physics and Astronomy

We present neutral hydrogen (HI) observations from the Very Large Array (VLA) telescope of the galaxies Haro 11, Pox 186, and VCC 1313. 24 hours of deep spectral line observation at the 21 cm line were obtained from the program 17B-287 of Haro 11, the primary galaxy studied in this capstone, and 176 and 203 respective minutes of archival VLA data at the 21 cm line were obtained from the program AS0832 of Pox 186 and VCC 1313, the secondary and tertiary sources of study for this capstone. Haro 11 is one of a very small number of local dwarf …

Binary Neutron Star Merger Rates. Predictions From Observations Of Dwarf Galaxies And Observable Rates With Ground-Based Gravitational-Wave Detectors, Karen Perez Sarmiento

Macalester Journal of Physics and Astronomy

Binary Neutron Star (BNS) mergers are interesting events in the field of multi-messenger astronomy since they are sources of detectable gravitational wave signals and electromagnetic transients. Here I introduce a new method to calculate a conservative, lower-limit for the rate of BNS merger events that is proportional to the stellar mass and is based on evidence of an r-process event in the dwarf galaxy Reticulum II. Two estimates of the stellar mass in the nearby universe were made using a Schechter Mass Function and a modified version of the 2MASS Extended Source Catalog (2MASS XSC). The BNS merger event rates …

Uv Led System For Pl Measurements On Gan Samples, Dona H. Pantova

Macalester Journal of Physics and Astronomy

Gallium Nitride materials are direct bandgap semiconductors with important applications, such as in the production of light-emitting diodes and transistors. The process of photoluminescence, in which excited electron and holes emit electro-magnetic radiation when they recombine, can be used to study the structure and quality of Gallium Nitride materials. Due to the size of the bandgap in these materials (3.4eV), ultraviolet light is required to create electron-hole pairs in GaN. We designed and built a system, which uses ultraviolet light, to take measurements on GaN samples provided by a local company, Lightwave Photonics, who were interested in the quality of …

Investigation On The Electrical Properties Of Cdo/Zno Thin Films Using Thz Spectroscopy, Ramon Molina

Macalester Journal of Physics and Astronomy

In this work, we study the electrical properties of transparent conducting oxides using physical and optical techniques. The objective is to characterize the conductivity of a series of cadmium oxide zinc-oxide thin films with varying cadmium concentrations using three methods. The Hall Effect estimates carrier concentration, sheet conductivity, and carrier mobility. Optical methods, such as FTIR spectroscopy, can provide estimates of the plasma frequency, which describes a metal’s transition from being transparent to opaque to light. THz spectroscopy extracts the complex conductivity of materials in the far infrared spectrum and provides insights on the optical transport properties of conductors. Our …

Understanding Solar Activity During The Last 400 Years, Sam Q. Hollenbach

Macalester Journal of Physics and Astronomy

The solar cycle has a profound effect on both terrestrial and extra-terrestrial operations. Understanding the history of the solar cycle is necessary for studying long term trends, however older data is difficult to calibrate due to the sparsity of observations. In this paper we propose a new method for calibrating sunspot number data that does not rely on observational overlap. Initial testing shows promise in this method’s success, though more work must be done to ensure calibration consistency across all observers.

Recent Evolution Of The Eta Carinae Supernova Imposter System, Greta L. Helmel

Macalester Journal of Physics and Astronomy

The supernova imposter Eta Carinae and its surrounding Homunculus reflection nebula have been of great interest for the last several decades. As the most massive star known in our Galaxy, this object is of particular importance in understanding high mass loss episodes and final stages in the evolution of other similarly massive stars in the later stages of their lives. Observations using the STIS CCD Instrument have been taken over the past 20 years for both the central star and the Homunculus as part of the Hubble Space Telescope (HST) Treasury Program on Eta Carinae. Recent changes in …

The Neutral Hydrogen Kinematics Of The Dwarf Galaxy Merger Ngc 3239, Robert N. Ford

Macalester Journal of Physics and Astronomy

We present H I spectral line images of the nearby dwarf galaxy NGC 3239. The galaxy’s curious morphology suggests that it is a post-merger system. We propose that NGC 3239 is a merger because it has multiple tidal tails, an enhanced velocity dispersion throughout the disk, and widespread star formation. We have produced kinematic moment maps corresponding to the H I column density, radial velocity, and velocity dispersion. Further, position velocity (P-V) slices of the galaxy were taken and three-color images were made using the SDSS G, R, and I, filters for comparison with the moment maps. These slices illustrate …

Hst/Stis Analysis Of The First Main Sequence Pulsar Cu Virginis, Jiří Krtička, Zdeněk Mikulášek, Gregory W. Henry, Jan Janík, Oleg Kochukhov, Andrzej Pigulski, P. Leto, Corrado Trigilio, Iva Krtičková, Theresa Lüftinger, Milan Prvák, A. Tichý

Information Systems and Engineering Management Research Publications

Context. CU Vir has been the first main sequence star that showed regular radio pulses that persist for decades, resembling the radio lighthouse of pulsars and interpreted as auroral radio emission similar to that found in planets. The star belongs to a rare group of magnetic chemically peculiar stars with variable rotational period.

Aims. We study the ultraviolet (UV) spectrum of CU Vir obtained using STIS spectrograph onboard the Hubble Space Telescope (HST) to search for the source of radio emission and to test the model of the rotational period evolution.

Methods. We used our own far-UV and visual photometric …

Equation Of State Of A Magnetized Dense Neutron System, Efrain J. Ferrer, Aric Hackebill

Physics & Astronomy Faculty Publications

We discuss how a magnetic field can affect the equation of state of a many-particle neutron system. We show that, due to the anisotropy in the pressures, the pressure transverse to the magnetic field direction increases with the magnetic field, while the one along the field direction decreases. We also show that in this medium there exists a significant negative field-dependent contribution associated with the vacuum pressure. This negative pressure demands a neutron density sufficiently high (corresponding to a baryonic chemical potential of ��=2.25 GeV) to produce the necessary positive matter pressure that can compensate for the gravitational pull. The …

Machine Learning Pipeline For Exoplanet Classification, George Clayton Sturrock, Brychan Manry, Sohail Rafiqi

SMU Data Science Review

Planet identification has typically been a tasked performed exclusively by teams of astronomers and astrophysicists using methods and tools accessible only to those with years of academic education and training. NASA’s Exoplanet Exploration program has introduced modern satellites capable of capturing a vast array of data regarding celestial objects of interest to assist with researching these objects. The availability of satellite data has opened up the task of planet identification to individuals capable of writing and interpreting machine learning models. In this study, several classification models and datasets are utilized to assign a probability of an observation being an exoplanet. …

On The Time-Frequency Downward Drifting Of Repeating Fast Radio Bursts, Weiyang Wang, Bing Zhang, Xuelei Chen, Renxin Xu

Physics & Astronomy Faculty Research

The newly discovered second repeating fast radio burst (FRB) source, FRB 180814.J0422+73, was reported to exhibit a time–frequency downward drifting pattern, which is also seen in the first repeater FRB 121102. We propose a generic geometrical model to account for the observed downward drifting of sub-pulse frequency, within the framework of coherent curvature radiation by bunches of electron–positron pairs in the magnetosphere of a neutron star (NS). A sudden trigger event excites these coherent bunches of charged particles, which stream outward along open field lines. As the field lines sweep across the line of sight, the bunches seen later travel …

The Sophie Search For Northern Extrasolar Planets Xiv. A Temperate (Teq ~ 300 K) Super-Earth Around The Nearby Star Gliese 411, R. F. Díaz, Xavier Delfosse, Melissa J. Hobson, Isabelle Boisse, Nicola Astudillo-Defru, Xavier Bonfils, Gregory W. Henry, Luc Arnold, François Bouchy, Vincent Bourrier, Bastien Brugger, Shweta Dalal, Magali Deleuil, Olivier Demangeon, F. Dolon, Xavier Dumusque, Thierry Forveille, Nathan Hara, Guillaume Hébrard, ‪Flavien Kiefer, Théodore Lopez, ‪Lucile Mignon, F. Moreau, Olivier Mousis, C. Moutou, Francesco Pepe, S. Perruchot, Y. Richaud, Alexandre Santerne, Nuno Santos, R. Sottile, Manu Stalport, Damien Ségransan, Stéphane Udry, N. Unger, Paul A. Wilson

Information Systems and Engineering Management Research Publications

Periodic radial velocity variations in the nearby M-dwarf star Gl 411 are reported, based on measurements with the SOPHIE spectrograph. Current data do not allow us to distinguish between a 12.95-day period and its one-day alias at 1.08 days, but favour the former slightly. The velocity variation has an amplitude of 1.6 m s−1, making this the lowest-amplitude signal detected with SOPHIE up to now. We have performed a detailed analysis of the significance of the signal and its origin, including extensive simulations with both uncorrelated and correlated noise, representing the signal induced by stellar activity. The signal is significantly …

Absolute Dimensions Of The Early F-Type Eclipsing Binary V506 Ophiuchi, Guillermo Torres, Claud H. Sandberg Lacy, Francis C. Fekel, Matthew W. Muterspaugh

Information Systems and Engineering Management Research Publications

We report extensive differential V-band photometry and high-resolution spectroscopic observations of the early F-type, 1.06-day detached eclipsing binary V506 Oph. The observations, along with times of minimum light from the literature, are used to derive a very precise ephemeris and the physical properties for the components, with the absolute masses and radii being determined to 0.7% or better. The masses are 1.4153 ± 0.0100 M☉ and 1.4023 ± 0.0094 M☉ for the primary and secondary, the radii are 1.725 ± 0.010 R☉ and 1.692 ± 0.012 R☉, and the effective temperatures are 6840 ± 150 K and 6780 ± 110 …

Stability Of Binary Colloidal Crystals Immersed In A Cholesteric Liquid Crystal, Setarehalsadat Changizrezaei, Colin Denniston

Physics and Astronomy Publications

In this paper, we model a number of both closed-packed and non-closed-packed crystals inside a cholesteric liquid crystal (LC) with different pitch values and nematic LC through the Landau–de Gennes free-energy method. We used binary boundary conditions (normal and planar anchoring) applied on the surface of colloids as we are interested in investigating the stability of binary crystals. The results indicate that body-centered-cubic (BCC) crystals have a lower-energy lattice defect structure than the diamond crystal, and the most energetically favorable BCC lattice can be formed in a cholesteric liquid crystal with a pitch value commensurate with the lattice spacing. Furthermore, …

Studies On The Generation And Detection Of Orbital Angular Momentum Based On Beam-Shaping Techniques, Xijie Luo

Physics & Astronomy ETDs

Light carrying orbital angular momentum (OAM) has many applications ranging from optical manipulation, imaging and remote sensing, and optical communications, and can be used to perform fundamental studies in quantum mechanics and quantum information. Moreover, single photons with high-order OAM allow for increasing the amount of information carried per photon in quantum communication. This thesis describes the study of methods for the preparation and detection of OAM of light in high mode order by utilizing beam shaping techniques using spatial light modulators (SLMs). The quality of the generated high-order OAM mode is limited by optical aberrations which are induced by …