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Candace Gray

NASA Earth and Space Science Fellow
Entered: 2010
Office: 220 Astronomy
Phone: (575)646-8180
Fax: (575)646-1602
E-mail: candaceg
(append "@nmsu.edu")
M.S.University of Texas, Austin,2008
B.S. University of Texas, El Paso, 2006


New Mexico State University, Las Cruces, NM
Ph.D in Astronomy
Thesis Title: The Effect of Solar Flares, Coronal Mass Ejections, and Co-rotating Interaction Regions on Venus's 5577 Å Oxygen Green Line
Thesis advisor: Dr. Nancy Chanover

University of Texas at Austin, Austin, TX
M.A. in Astronomy
Thesis Title: A Chemical Survey of 67 Comets Conducted at McDonald Observatory
Thesis advisor: Drs. Anita Cochran and Edward Robinson

University of Texas at El Paso, El Paso, TX
B.S. in Physics with minor studies in Mathematics
Thesis Title: Radio Observations of Magnetic Cataclysmic Variable Stars at the Very Large Array
Thesis advisor: Dr. Paul Mason


For the past 5 years my collaboration and I have conducted observations of the Venusian nightglow, specifically the OI (1S-1D) transition at 557.7 nm, referred to as the oxygen green line. The green line is an enigmatic feature on Venus. It is highly temporally variable, observed to be brighter than the Earth's nightglow on some nights and undetectable on other nights. I hypothesized that the green line is not true nightglow but, rather, is an auroral-type emission that occurs after large solar storms. Observations taken using the high resolution Astrophysical Research Consortium Echelle Spectrograph on the 3.5m telescope at Apache Point Observatory revealed that green line intensity increases after coronal mass ejection (CME) impacts.

The 1D state of oxygen drops to the 3P ground state, producing the oxygen red line at 630.0 nm. The red line is seen in the terrestrial aurora but not in the nightglow, which occurs at lower altitudes leading to collisional quenching of the 1D state. The red line has never been detected on Venus, suggesting the green line is occurring low in the atmosphere, below 150 km. However, if the green line is an auroral process, then solar wind electrons must be precipitating low in to the Venusian nightside atmosphere.

Using data from ASPERA-$ and VeRA onboard Venus Express, we compared electron density profiles and electron energy spectra before and after CMEs. We discovered that after CME impacts, electrons in the V1 ionospheric layer (~130 km) increased while electron density in the V2 layer (~150 km) decreased. Additionally, electron energy increased from typical solar wind values of ~12 eV to values as high as 70 eV and electron flux increased by over an order of magnitude. Using these values as input into the 1-D magnetohydrodynamic TRANSCAR model developed by Pierre-Louis Blelly, we found that production of the green line was most sensitive to electron energy and that intense green line emission is produced, with only weak red line emission, after CMEs.

Future work for this project will focus on making improvements to the TRANSCAR model in order to adequately model nightside electron density profiles. This will involve making modification to the neutral atmosphere, increasing the number of green line production and loss mechanisms, and explore the importance of an increased magnetic field at the top of the atmosphere. We hypothesize that increased dynamic pressure from a CME passage compresses the Venusian ionopause to such a degree that ionic flow from the dayside ionosphere is stopped. The V2 layer is controlled by dayside O+ ions and this would explain the decrease in V2 electrons. Additionally, an increase in the the magnetic field strength may drive increased electron precipitation into the Venusian nightside ionosphere, increasing oxygen green line emission.


I worked with Edward Robinson at the University of Texas at Austin on interacting binary stars, reducing CCD photometry data and generating light curves, and conducting telescope observations at McDonald Observatory. Our work on the UW Coronaw Borealis system was published in ApJ in 2008.

I worked with Anita Cochran on comet spectroscopy at the University of Texas at El Paso from 2006 - 2009. I analyzed more than 25 years of optical spectroscopy from the McDonald Observatory for roughly 100 hundred comets, studying their chemical compositions in order to distinguish between Oort Cloud and Kuiper belt objects. I built on identified a new class of comets which are depleted in C3 but not in C2. This work formed the body of my M.S. thesis.

As an undergrad at the University of Texas at El Paso (UTEP), I worked with Dr. Paul Mason studying magnetic cataclysmic variables (MCV) stars. We used the Very Large Array (VLA) to measure radio emission of several MCVs and we discovere the strongly magnetized system AR UMa to be a strong radio emitter.


While at UTEP, I collaborated with Niesjca Turner in the field of astronomy education. I taught laboratory exercises for undergraduates using a three-dimensional visualization system called GeoWall, designed to illustrate lunar phases. Students were surveyed pre- and post-usage, and we presented the results at several American Geophysical Union conferences.

My interests in teaching developed further while in Austin, where I taught classes ranging from elementary to high school levels as a part of the UTeach program which emphisized project-based instruction. I designed, taught, and lead a team of other UTeach student in a 3 week high-school project where we taught students how to design and build their own telescopes. I won the award for best new project for my design of teaching physics by building a pinball machine.


International Venus Conference Travel Grant, 2013
Comparative Climatology of Terrestrial Planets Travel Grant, 2012
NASA Earth and Space Science (NESSF) Award, 2012
New Mexico State University College of Arts and Science Travel Grant, 2012
Third place in New Mexico State University's 3 Minute Thesis Competition, 2012
New Mexico State University Peagasus Award for Excellence in Teaching, 2011
Division of Planetary Science Hartmann Travel Grand, 2011
UT Austin, UTeach Lucas Award for best Project-Based Instruction project "The Physics of Pinball", 2010
UT Austin Graduate Enrichment Fellowship, 2006 - 2007
Minority Access to Research Careers (MARC) Scholar, 2004 - 2006
Presidentail Scholarship, University of Texas at El Paso, 2001 - 2005


Astronomical League Convention, Las Cruces, NM. July 2015
"The Effect of Solar Flares, Coronal Mass Ejections, and Co-rotating Interaction Regions on Venus's 5577 Å Oxygen Green Line"

American Astronomical Society Division of Planetary Science, Tucson, AZ. November 2014´
Venus's Mysterious Oxygen Green Line: An Auroral Process?"

Apache Point Observatory 3.5m 20th Anniversary Celebration, Sunspot, NM. May 2014
"Venus's Mysterious Aurora"

NMSU Graduate Research Arts and Science Symposium, Las Cruces, NM. March 2014
"Aurora’s on Venus?" European Space and Technology Center Seminar, Noordwijk, Netherlands. June 2013
"Coronal Mass Ejections and Their Effect on the Venusian Nightglow"

International Venus Conference, Catania, Sicily. June 2013
"Coronal Mass Ejections and Their Effect on the Venusian Nightglow"

NMSU Graduate Research Arts and Science symposium, Las Cruces, NM. March 2013
"Venus's Oxygen Green Line and its Connection with Solar Activity"

Las Cruces Astronomical Society, Las Cruces, NM. February 2013
"The Moons of Jupiter"

American Geophysical Union, San Francisco, CA. December 2012
Coronal Mass Ejections and Their Effect on the Venusian Nightglow

Laboratory of Atmospheric and Space Physics Colloquium, Boulder, CO. November 2012
"The Bastille Day II Solar Storm Event and Its Impact on the Venusian Nightglow"

Las Cruces Astronomical Society, Las Cruces, NM. July 2012
"The Sun's Effect on the Planets"


Venus' Oxygen Green Line: An Auroral Process?
Gray, C.L., Chanover, N.J., Slanger, T., Moliverdikani, K., Peter, K., Häusler, B., Tellmann, S., 2014.
Submitted to Planetary and Space Science, 2015.

The Effect of Solar Flares, Coronal Mass Ejections, and Solar Wind Streams on Venus' 5577Å Oxygen Green Line.
Gray, C.L, Chanover, N.J., Slanger, T., Moliverdikhani, K., 2014.

Thirty Years of Cometary Spectroscopy from McDonald Observatory.
Anita L. Cochran, Edwin S. Barker, Candace L. Gray, 2012, Icarus, 218, 144-168.

Recent Observations of Venus' OI and O2 Emission from Apache Point Observatory
Candace L. Gray, Nancy J. Chanover, Tom G. Slanger.

The Orbital Period and Time-variable Asymmetric Accretion Disk in the X-Ray Binary MS 1603.6+2600 (=UW Coronae Borealis)
Paul A. Mason, Edward L. Robinson, Candace L. Gray, & Robert I. Hynes 2008, ApJ, 685, 428-435

A Chemical Survey of 73 Comets Conducted at McDonald Observatory
Candace L. Gray & A. L. Cochran 2008, BAAS, 40, 411

AR Ursae Majoris Discovered to Be a Persistent Radio Polar: Results from a VLA Survey of Magnetic Cataclysmic Variables
Paul A. Mason & Candace L. Gray 2007, ApJ, 660, 662-668

CCD Photometry of UW Coronae Borealis
Paul A. Mason, Edward L. Robinson, & Candace L. Gray 2006, BAAS, 38, 84

AR Ursae Majoris: A New Persistent Radio Emitter
C. L. Gray & P. A. Mason 2005, BAAS, 37, 496

An Investigation of Radio Emission in Magnetic Cataclysmic Variables
P. A. Mason & C. Gray 2004, ASPC, 315, 237

Effectiveness of GeoWall Visualization Technology for Conceptualization of the Sun-Earth-Moon System
N. E. Turner, C. Gray, & E. J. Mitchell 2004, AGUFM, ED11A-06

A VLA Survey of Magnetic Cataclysmic Variable Stars
C. Gray & P. A. Mason 2004, RMxACm 20, 267

A VLA Survey of Magnetic Cataclysmic Variables: The First Radio Detection of the High Field Polar, AR UMa
C. Gray & P. A. Mason 2004, BAAS, 36, 982

Effectiveness of GeoWall Technology in Conceptualizing Lunar Phases
N. Turner, R. Lopez, K. Hamed, D. Corralez, & C. Gray 2004, COSP, 35, 4104


In addition to researching the Venusian atmosphere, I also enjoy creating space art style painting. Two examples of my work are shown below. Inside the ladybug are the Horsehead, Eagle, and Snowball Nebula, M100, Venus, the north star, comet Hale-Bopp, the Sun with Venus transiting. This painting was made for a friend and true lady of astronomy. The painting on the right is of AR UMa, the highest known magnetic field polar, a type of interacting binary star system.