- Greater Denver Area
Nikta Amiri's Overview
- Research Associate at University of Colorado at Boulder
- Astrophysicist at Leiden Observatory/ Joint Institute for VLBI in Europe
- MSc student at Jodrell Bank Observatory
Nikta Amiri's Summary
I am a postdoctoral fellow of Astrophysics at the University of Colorado at Boulder. I have significant experience in project management, data analysis, and strong focus on learning new concepts, collaboration, and growth:
My expertise include:
• Statistical analysis (large datasets), hypothesis testing, survival analysis, machine learning, and principal component analysis
• Data science
• Communication, troubleshooting technical problems
• Advanced visualization, and data exploitation
• Model and algorithm development
• Analysis of remote sensing data from satellites and ground based telescopes
• Radio frequency signal processing, synthetic aperture interferometry, polarimetry
• Strategic problem solving
• Presentation skills
• Project management, international collaboration
• Professional briefings, reports, and proposals
Nikta Amiri's Experience
Educational Institution; 5001-10,000 employees; Higher Education industry
August 2012 – Present (2 years 2 months) Boulder, CO
My research focuses on astrometric monitoring of maser emitting regions in the Andromeda galaxy (M31), to measure its transverse velocity and geometric distance.
My research experience include:
• Use advanced statistical analysis including survival analysis, and hypothesis testing, to insure the accuracy of measurements and uncertainty estimates.
• Perform signal processing of remote sensing data from radio telescopes and infrared satellites.
• Plan, coordinate, and operate on-site and off-site radio astronomical observations.
• Code an efficient data analysis pipeline to extract astronomical sources from large data sets (hundreds of GB and TB size).
• Utilize machine learning tools including principal component analysis, and regression on astronomical data.
• Develop algorithms in Python, Matlab, and R for analysis of data from Spitzer and Herschel satellites.
• Develop several innovative proposals as a primary investigator for astronomical observations.
• Collaborate with scientists in the United States and Europe in multi-institutions as the team leader
or member of an N-person team.
• Perform technical trouble shooting, test, and verification of astronomical observations.
Educational Institution; 5001-10,000 employees; Research industry
September 2007 – October 2011 (4 years 2 months) Leiden University, The Netherlands
• Developed a data mining algorithm to characterize sources detected from astronomical observa
• Developed software in Fortran to model an astrophysical system and compare the numerical results with astronomical observations.
• Successfully submitted several proposals as a primary investigator in collaboration with scientists in the United States and Europe.
• Led several on-site and off-site astronomical observations using various telescope facilities in the United States and Europe.
• Performed image processing and calibration of microwave remote sensing data from synthetic aperture interferometers including the US based Very Long Baselines Array, the European VLBI Network, and the Very Large Array.
Educational Institution; 10,001+ employees; Research industry
September 2006 – September 2007 (1 year 1 month) University of Manchester, UK
Nikta Amiri's Volunteer Experience & Causes
Nikta Amiri's Courses
MSc, Astronomy & Astrophysics
The University of Manchester
- Galactic Astronomy
- Frontiers of Astrophysics
- Radio Astronomy
Nikta Amiri's Languages
English(Full professional proficiency)
Persian(Native or bilingual proficiency)
Nikta Amiri's Honors and Awards
Marie Curie fellowship
- September 2007
European Framework 6 Marie Curie Early Stage Training fellowship
Nikta Amiri's Skills & Expertise
- Data Visualization
- Radio Frequency Engineering
- synthetic aperture interferometry
- Proposal Leadership
- Project Management
- international collaboration
- Remote Sensing
- Microwave Synthesis
- Statistical Data Analysis
- Principal Component Analysis
- Regression Analysis
- Survival Analysis
- systems engineering
- Large-scale Data Analysis
- Image Processing
- IDL programming
- Numerical Analysis
- Signal Processing
- Machine Learning
- Scientific Computing
Nikta Amiri's Publications
- Astronomy & Astrophysics
- January 2012
SiO maser emission occurs in the extended atmosphere of evolved stars and can be studied at high angular resolution. Very long baseline interferometry (VLBI) observations of Mira variables indicate that SiO masers are significantly linearly polarized with linear polarization fraction up to 100%. However, no information is available at high angular resolution for SiO masers in higher mass loss OH/IR stars. We extend the VLBI SiO maser studies to OH/IR stars. The observations enable us to understand the SiO pumping mechanisms in higher mass loss evolved objects and compare those with Mira variables. Additionally, polarimetric observations of SiO masers help us to understand the magnetic field strength and morphology and to distinguish between conflicting polarization theories. The 43 GHz SiO maser observations of the OH/IR star OH 44.8-2.3 were performed with the VLBA in full polarization spectral line mode. Auxiliary EVLA observations were performed to allow for the absolute calibration of the polarization angle. The Zeeman splitting was measured by cross correlating the right and left circular polarization spectra as well as the S-curve fitting. Additionally, we analyzed the 1612 MHz OH maser observations of OH 44.8-2.3 from the VLA archive. The SiO masers of OH 44.8-2.2 form a ring located at ~5.4 AU around the star. The masers appear to be highly linearly polarized with fractional linear polarization up to 100%. The linear polarization vectors are consistent with a dipole field morphology in this star. We report a tentative detection of circular polarization of ~0.7% for the brightest maser feature. The magnetic field measured for this feature corresponds to 1.5\pm0.3 G. Additionally, the distribution of the 1612 MHz OH maser emission could indicate an elongated morphology.
- Astronomy & Atrophysics Journal
- Astronomy & Astrophysics Journal
- January 2010
Maser emission occurs in different regions of the circumstellar envelopes (CSEs) of evolved stars and can be studied at high angular resolution using radio interferometers. These masers are useful probes of the dynamics and kinematics of the outflow from AGB stars. Moreover, masers can be important tracers of the magnetic field strength and morphology at various distances from the central stars. It is expected that the magnetic field plays an important role in transforming spherically symmetric asymptotic giant branch (AGB) stars into a-spherical planetary nebulae (PNe). Theoretical modeling indicated that magnetically collimated jets may be responsible for the formation of the a-spherical PNe. Water fountain sources are a class of post-AGB objects in which H2O masers indicate high velocity collimated jets. Our radio interferometric observations indicate that asymmetries are also present in the OH maser region of the envelope. We performed kinematical reconstruction in order to understand the distribution of OH masers in the CSEs of these stars. Our results show that the OH masers could have either equatorial or bi-conical distribution. Additionally, the observations reveal significant field strength for the OH maser region of these objects, which show the possible role of the magnetic field in collimating the CSEs.
At distances close to the central stars, between the photosphere and the dust formation zone, SiO masers occur. SiO maser polarimetry has been performed for Mira variables and supergiants and seems to indicate dynamically significant and ordered magnetic fields. We extended these studies and performed VLBA SiO maser polarization observations of objects with more extreme mass-loss, in order to understand the origin of the transition between the AGB and PNe. These observations will enable us to understand the SiO emission mechanisms and possibly distinguish between competing models on the origin of the SiO maser polarization.
- Asymmetric Planetary Nebulae 5 conference, held in Bowness-on-Windermere, U.K., 20 - 25 June 2010, A. A. Zijlstra, F. Lykou, I. McDonald, and E. Lagadec, eds. (2011) Jodrell Bank Centre for Astrophysics
Water fountain sources are a class of post-AGB stars that exhibit highly collimated H_2O maser jets. These jets are likely associated with the origin of asymmetric PNe. Magnetic fields are found to play an important role in collimating these jets. We measured the Zeeman splitting of the 1612 MHz OH masers in W43A, which is an archetype of this class of objects. A magnetic field of 100μG was derived for the OH maser region of this source. Additionally, we performed kinematical re-construction of the OH maser region of this source. Our results show that the OH masers are most likely distributed in the equatorial region of the circumstellar envelope . The equatorial enhancement of the OH masers could be due to the presence of a binary companion.
Nikta Amiri's Education
2007 – 2011
Thesis: "Developing Asymmetries in AGB stars: Occurrence, Morphology, and Polarization of Circumstellar Masers"
Promotor: Prof. Ewine van Dishoeck
Supervisors: Dr. Huib Jan van Langevelde, Dr. Wouter Vlemmings (Onsala Space Observatory)
MSc, Astronomy & Astrophysics
2006 – 2007
Thesis: ”Anomalous Emission from Dust in HII Regions”
Supervisors: Prof. Rod Davies, Prof. Peter Wilkinson
BSc, Mechanical Engineering
2001 – 2005
Nikta Amiri's Additional Information
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