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Figure 6: Simulation Results For Flux Tube Entropy And Specific Entropy In Saturn's Magnetosphere, Xuanye Ma, Peter A. Delamere, Michelle F. Thomsen, Antonius Otto, Bishwa Neupane, Brandon Burkholder, Katariina Nykyri 2019 Embry-Riddle Aeronautical University

Figure 6: Simulation Results For Flux Tube Entropy And Specific Entropy In Saturn's Magnetosphere, Xuanye Ma, Peter A. Delamere, Michelle F. Thomsen, Antonius Otto, Bishwa Neupane, Brandon Burkholder, Katariina Nykyri

Katariina Nykyri

No abstract provided.


Microcontroller Differential Gps To Subtract Signal Delay Due To Ambient Free Electrons In The Ionosphere, Diana Jane Swanson 2019 California Polytechnic State University, San Luis Obispo

Microcontroller Differential Gps To Subtract Signal Delay Due To Ambient Free Electrons In The Ionosphere, Diana Jane Swanson

Physics

The goal of this project is to create a Global Positioning System (GPS) receiver that is more precise than one GPS receiver on its own. The technique is to take the difference between a GPS receiver’s measured position and its actual position, then use radio frequency (RF) communication to send that differential value to another microcontroller GPS receiver. This differential value will be added to the measured second location to get a more accurate position for the second GPS receiver, thus creating a differential GPS.


Long-Term Dust Formation By Core Collapse Supernovae, Kelsie Marie Krafton 2019 Louisiana State University and Agricultural and Mechanical College

Long-Term Dust Formation By Core Collapse Supernovae, Kelsie Marie Krafton

LSU Doctoral Dissertations

Studying long-term dust formation by CCSNe is an important step toward understanding the large dust masses found in early galaxies. The amazing new discovery of approximately a solar mass of cold dust in the ejecta of SN 1987A has caused a complete re-evaluation of dust formation in core collapse supernovae (CCSNe). CCSNe form only a small amount of dust after three years, but SN 1987A has a dust mass that is several orders of magnitude larger after 25 years. A recent study of SN 2010jl by Gall et al. (2014) made the fascinating suggestion that dust is continuously forming in ...


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 2019 Nanjing University

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 Publications

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 multiband ...


Arecibo Message, Joshua P. Tan 2019 CUNY La Guardia Community College

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.


Real-Time Rfi Mitigation In Radio Astronomy, Emily Ramey, Nick Joslyn, Richard Prestage, Michael Lam, Luke Hawkins, Tim Blattner, Mark Whitehead 2019 Washington University in St. Louis

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 ...


Relativistic Astronomy. Ii. In-Flight Solution Of Motion And Test Of Special Relativity Light Aberration, Jin-Ping Zhu, Bing Zhang, Yuan-Pei Yang 2019 Peking University

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 Publications

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 ...


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 2019 Beijing Normal University

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 Publications

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 ...


Haro 11, Pox 186, And Vcc 1313: The Enigmatic Behavior Of Hi Non-Emitters, Sarah H. Taft 2019 Macalester College

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 2019 Macalester College

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 2019 Macalester College

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 ...


Investigation On The Electrical Properties Of Cdo/Zno Thin Films Using Thz Spectroscopy, Ramon Molina 2019 Macalester College

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 ...


Understanding Solar Activity During The Last 400 Years, Sam Q. Hollenbach 2019 Macalester College

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 2019 Macalester College

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 spectra ...


The Neutral Hydrogen Kinematics Of The Dwarf Galaxy Merger Ngc 3239, Robert N. Ford 2019 Macalester College

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 ...


Tik-Means: Transformation-Infused K-Means Clustering For Skewed Groups, Nicholas S. Berry, Ranjan Maitra 2019 Iowa State University

Tik-Means: Transformation-Infused K-Means Clustering For Skewed Groups, Nicholas S. Berry, Ranjan Maitra

Ranjan Maitra

The K-means algorithm is extended to allow for partitioning of skewed groups. Our algorithm is called TiK-Means and contributes a K-means type algorithm that assigns observations to groups while estimating their skewness-transformation parameters. The resulting groups and transformation reveal general-structured clusters that can be explained by inverting the estimated transformation. Further, a modification of the jump statistic chooses the number of groups. Our algorithm is evaluated on simulated and real-life datasets and then applied to a long-standing astronomical dispute regarding the distinct kinds of gamma ray bursts.


Multivariate T-Mixture-Model-Based Cluster Analysis Of Batse Catalogue Establishes Importance Of All Observed Parameters, Confirms Five Distinct Ellipsoidal Sub-Populations Of Gamma-Ray Bursts, Souradeep Chattopadhyay, Ranjan Maitra 2019 Iowa State University

Multivariate T-Mixture-Model-Based Cluster Analysis Of Batse Catalogue Establishes Importance Of All Observed Parameters, Confirms Five Distinct Ellipsoidal Sub-Populations Of Gamma-Ray Bursts, Souradeep Chattopadhyay, Ranjan Maitra

Ranjan Maitra

Determining the kinds of gamma-ray bursts (GRBs) has been of interest to astronomers for many years. We analysed 1599 GRBs from the Burst and Transient Source Experiment (BATSE) 4Br catalogue using t-mixture-model-based clustering on all nine observed parameters (T50, T90, F1, F2, F3, F4, P64, P256, and P1024) and found evidence of five types of GRBs. Our results further refine our earlier findings by providing groups that are more distinct. Using the classification scheme of past authors that employed duration, total fluence (Ft = F1 + F2 + F3 ...


Gaussian-Mixture-Model-Based Cluster Analysis Finds Five Kinds Of Gamma-Ray Bursts In The Batse Catalogue, Souradeep Chattopadhyay, Ranjan Maitra 2019 University of Calcutta

Gaussian-Mixture-Model-Based Cluster Analysis Finds Five Kinds Of Gamma-Ray Bursts In The Batse Catalogue, Souradeep Chattopadhyay, Ranjan Maitra

Ranjan Maitra

Clustering methods are an important tool to enumerate and describe the different coherent kind of gamma-ray bursts (GRBs). But their performance can be affected by a number of factors such as the choice of clustering algorithm and inherent associated assumptions, the inclusion of variables in clustering, nature of initialization methods used or the iterative algorithm or the criterion used to judge the optimal number of groups supported by the data. We analysed GRBs from the Burst and Transient Source Experiment (BATSE) 4Br Catalog using k-means and Gaussian-mixture-models-based clustering methods and found that after accounting for all the above factors, all ...


Machine Learning Pipeline For Exoplanet Classification, George Clayton Sturrock, Brychan Manry, Sohail Rafiqi 2019 Southern Methodist University

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 ...


On The Time-Frequency Downward Drifting Of Repeating Fast Radio Bursts, Weiyang Wang, Bing Zhang, Xuelei Chen, Renxin Xu 2019 Chinese Academy of Sciences

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

Physics & Astronomy Faculty Publications

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 ...


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