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Double-offset Cassegrain telescopes for the Ultraviolet Type Ia (UVIa) mission concept
Authors:
Fernando Cruz Aguirre,
Keri Hoadley,
Curtis McCully,
Gillian Kyne,
Shouleh Nikzad,
John Hennessy,
April D. Jewell,
Christophe Basset,
Daniel Harbeck,
Greyson Davis,
Leonidas A. Moustakas,
D. Andrew Howell,
Saurabh W. Jha,
David J. Sand,
Peter Brown,
Ken Shen
Abstract:
Our understanding of cosmology is shaped by Type Ia supernovae (SNe Ia), the runaway thermonuclear detonations of white dwarfs via accretion from a companion star. The nature of this companion star is highly debated, with disparate models explaining currently available SNe Ia data. Critical ultraviolet (UV) signatures of SNe Ia progenitors are only observable within the first few days post-detonat…
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Our understanding of cosmology is shaped by Type Ia supernovae (SNe Ia), the runaway thermonuclear detonations of white dwarfs via accretion from a companion star. The nature of this companion star is highly debated, with disparate models explaining currently available SNe Ia data. Critical ultraviolet (UV) signatures of SNe Ia progenitors are only observable within the first few days post-detonation. We present the instrument design of UVIa, a proposed SmallSat to make early UV observations of SNe Ia. UVIa conducts simultaneous observations in three photometric channels: far-UV (1500 - 1800 Å), near-UV (1800 - 2400 Å), and Sloan $u$-band (3000 - 4200 Å). UVIa employs two 80 mm double-offset Cassegrain UV telescopes and a similar 50 mm $u$-band telescope, imaging onto three Teledyne e2v CIS120-10-LN CMOS detectors. The UV detectors are delta-doped for enhanced sensitivity, with custom metal-dielectric filters providing further in-band efficiency and red light rejection. The UV optics utilize multi-layer coatings, defining the UV bandpasses and providing additional red light rejection. The instrument design achieves high UV sensitivity (21.5 mag AB) and superior red light rejection ($<$ 10$^{-5}$ throughput), allowing UVIa to make early observations of SNe Ia while serving as a pathfinder for future UV transient telescopes.
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Submitted 21 July, 2025;
originally announced July 2025.
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A Nearby Dark Molecular Cloud in the Local Bubble Revealed via H$_2$ Fluorescence
Authors:
Blakesley Burkhart,
Thavisha E. Dharmawardena,
Shmuel Bialy,
Thomas J. Haworth,
Fernando Cruz Aguirre,
Young-Soo Jo,
B-G Andersson,
Haeun Chung,
Jerry Edelstein,
Isabelle Grenier,
Erika T. Hamden,
Wonyong Han,
Keri Hoadley,
Min-Young Lee,
Kyoung-Wook Min,
Thomas Müller,
Kate Pattle,
J. E. G. Peek,
Geoff Pleiss,
David Schiminovich,
Kwang-Il Seon,
Andrew Gordon Wilson,
Catherine Zucker
Abstract:
A longstanding prediction in interstellar theory posits that significant quantities of molecular gas, crucial for star formation, may be undetected due to being ``dark" in commonly used molecular gas tracers, such as carbon monoxide. We report the discovery of Eos, the closest dark molecular cloud, located just 94 parsecs from the Sun. This cloud is the first molecular cloud ever to be identified…
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A longstanding prediction in interstellar theory posits that significant quantities of molecular gas, crucial for star formation, may be undetected due to being ``dark" in commonly used molecular gas tracers, such as carbon monoxide. We report the discovery of Eos, the closest dark molecular cloud, located just 94 parsecs from the Sun. This cloud is the first molecular cloud ever to be identified using H$_2$ far ultra-violet (FUV) fluorescent line emission, which traces molecular gas at the boundary layers of star-forming and supernova remnant regions. The cloud edge is outlined along the high-latitude side of the North Polar Spur, a prominent x-ray/radio structure. Our distance estimate utilizes 3D dust maps, the absorption of the soft X-ray background, and hot gas tracers such as O\,{\sc vi}; these place the cloud at a distance consistent with the Local Bubble's surface. Using high-latitude CO maps we note a small amount (M$_{\rm{H}_2}\approx$20-40\,M$_\odot$) of CO-bright cold molecular gas, in contrast with the much larger estimate of the cloud's true molecular mass (M$_{\rm{H}_2}\approx3.4\times 10^3$\,M$_\odot$), indicating most of the cloud is CO-dark. Combining observational data with novel analytical models and simulations, we predict this cloud will photoevaporate in 5.7 million years, placing key constraints on the role of stellar feedback in shaping the closest star-forming regions to the Sun.
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Submitted 24 April, 2025;
originally announced April 2025.
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The Ultraviolet Type Ia Supernova CubeSat (UVIa): Science Motivation & Mission Concept
Authors:
Keri Hoadley,
Curtis McCully,
Gillian Kyne,
Fernando Cruz Aguirre,
Moira Andrews,
Christophe Basset,
K. Azalee Bostroem,
Peter J. Brown,
Greyson Davis,
Erika T. Hamden,
Daniel Harbeck,
John Hennessy,
Michael Hoenk,
Griffin Hosseinzadeh,
D. Andrew Howell,
April Jewell,
Saurabh Jha,
Jessica Li,
Peter Milne,
Leonidas Moustakas,
Shouleh Nikzad,
Craig Pellegrino,
Abigail Polin,
David J. Sand,
Ken J. Shen
, et al. (1 additional authors not shown)
Abstract:
The Ultraviolet (UV) Type Ia Supernova Mission (UVIa) is a CubeSat/SmallSat concept that stands to test critical space-borne UV technology for future missions like the Habitable Worlds Observatory (HWO) while elucidating long-standing questions about the explosion mechanisms of Type Ia supernovae (SNe Ia). UVIa will observe whether any SNe Ia emit excess UV light shortly after explosion to test pr…
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The Ultraviolet (UV) Type Ia Supernova Mission (UVIa) is a CubeSat/SmallSat concept that stands to test critical space-borne UV technology for future missions like the Habitable Worlds Observatory (HWO) while elucidating long-standing questions about the explosion mechanisms of Type Ia supernovae (SNe Ia). UVIa will observe whether any SNe Ia emit excess UV light shortly after explosion to test progenitor/explosion models and provide follow-up over many days to characterize their UV and optical flux variations over time, assembling a comprehensive multi-band UV and optical low-redshift anchor sample for upcoming high-redshift SNe Ia surveys (e.g., Euclid, Vera Rubin Observatory, Nancy Roman Space Telescope). UVIa's mission profile requires it to perform rapid and frequent visits to newly discovered SNe Ia, simultaneously observing each SNe Ia in two UV bands (FUV: 1500-1800A and NUV: 1800-2400A) and one optical band (u-band: 3000-4200A). In this study, we describe the UVIa mission concept science motivation and basic mission design. The UVIa mission concept has been submitted to the CubeSats category of the NASA ROSES Astrophysics Research & Analysis (APRA) program (\$10M cost cap) and NASA Astrophysics Pioneers program (\$20M cost cap).
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Submitted 19 December, 2025; v1 submitted 17 February, 2025;
originally announced February 2025.
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MAUVE: An Ultraviolet Astrophysics Probe Mission Concept
Authors:
Mayura Balakrishnan,
Rory Bowens,
Fernando Cruz Aguirre,
Kaeli Hughes,
Rahul Jayaraman,
Emily Kuhn,
Emma Louden,
Dana R. Louie,
Keith McBride,
Casey McGrath,
Jacob Payne,
Tyler Presser,
Joshua S. Reding,
Emily Rickman,
Rachel Scrandis,
Teresa Symons,
Lindsey Wiser,
Keith Jahoda,
Tiffany Kataria,
Alfred Nash,
Team X
Abstract:
We present the mission concept "Mission to Analyze the UltraViolet universE" (MAUVE), a wide-field spectrometer and imager conceived during the inaugural NASA Astrophysics Mission Design School. MAUVE responds to the 2023 Announcement of Opportunity for Probe-class missions, with a budget cap of \…
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We present the mission concept "Mission to Analyze the UltraViolet universE" (MAUVE), a wide-field spectrometer and imager conceived during the inaugural NASA Astrophysics Mission Design School. MAUVE responds to the 2023 Announcement of Opportunity for Probe-class missions, with a budget cap of \$1 billion, and would hypothetically launch in 2031. However, the formulation of MAUVE was an educational exercise and the mission is not being developed further. The Principal Investigator-led science of MAUVE aligns with the priorities outlined in the 2020 Astrophysics Decadal Survey, enabling new characterizations of exoplanet atmospheres, the early-time light curves of some of the universe's most explosive transients, and the poorly-understood extragalactic background light. Because the Principal Investigator science occupies 30% of the observing time available during the mission's 5 yr lifespan, we provide an observing plan that would allow for 70% of the observing time to be used for General Observer programs, with community-solicited proposals. The onboard detector (THISTLE) claims significant heritage from the Space Telescope Imaging Spectrograph on Hubble, but extends its wavelength range down to the extreme UV. We note that MAUVE would be the first satellite in decades with the ability to access this regime of the electromagnetic spectrum. MAUVE has a field of view of 900" x 900" a photometric sensitivity extending to $m_{UV}\leq 24$, and a resolving power of $R\sim1000$. This paper provides full science and mission traceability matrices for this concept, and also outlines cost and scheduling timelines aimed at enabling a within-budget mission and an on-time launch.
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Submitted 6 November, 2024;
originally announced November 2024.
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The High-Energy Spectrum of the Young Planet Host V1298 Tau
Authors:
Girish M. Duvvuri,
P. Wilson Cauley,
Fernando Cruz Aguirre,
Roy Kilgard,
Kevin France,
Zachory K. Berta-Thompson,
J. Sebastian Pineda
Abstract:
V1298 Tau is a young pre-main sequence star hosting four known exoplanets that are prime targets for transmission spectroscopy with current-generation instruments. This work pieces together observations from the NICER X-ray telescope, the Space Telescope Imaging Spectrograph and Cosmic Origins Spectrograph instruments aboard Hubble Space Telescope, and empirically informed models to create a panch…
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V1298 Tau is a young pre-main sequence star hosting four known exoplanets that are prime targets for transmission spectroscopy with current-generation instruments. This work pieces together observations from the NICER X-ray telescope, the Space Telescope Imaging Spectrograph and Cosmic Origins Spectrograph instruments aboard Hubble Space Telescope, and empirically informed models to create a panchromatic spectral energy distribution for V1298 Tau spanning 1 to 100000 Angstroms. We describe the methods and assumptions used to assemble the panchromatic spectrum and show that despite this star's brightness, its high-energy spectrum is near the limit of present X-ray and ultraviolet observatories' abilities to characterize. We conclude by using the V1298 Tau spectrum as a benchmark for the activity saturation stage of high-energy radiation from solar-mass stars to compare the lifetime cumulative high-energy irradiation of the V1298 Tau planets to other planets orbiting similarly massive stars.
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Submitted 29 September, 2023;
originally announced October 2023.
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The Radiation Environments of Middle-Aged F-Type Stars
Authors:
F. Cruz Aguirre,
K. France,
N. Nell,
N. Kruczek,
B. Fleming,
P. C. Hinton,
S. Ulrich,
P. R. Behr
Abstract:
Far ultraviolet (FUV) emission lines from dwarf stars are important driving sources of photochemistry in planetary atmospheres. Properly interpreting spectral features of planetary atmospheres critically depends on the emission of its host star. While the spectral energy distributions (SEDs) of K- and M-type stars have been extensively characterized by previous observational programs, the full X-r…
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Far ultraviolet (FUV) emission lines from dwarf stars are important driving sources of photochemistry in planetary atmospheres. Properly interpreting spectral features of planetary atmospheres critically depends on the emission of its host star. While the spectral energy distributions (SEDs) of K- and M-type stars have been extensively characterized by previous observational programs, the full X-ray to infrared SED of F-type stars has not been assembled to support atmospheric modeling. On the second flight of the Suborbital Imaging Spectrograph for Transition-region Irradiance from Nearby Exoplanet host stars (SISTINE-2) rocket-borne spectrograph, we successfully captured the FUV spectrum of Procyon A (F5 IV-V) and made the first simultaneous observation of several emission features across the FUV bandpass (1010 - 1270 and 1300 - 1565 Å) of any cool star. We combine flight data with stellar models and archival observations to develop the first SED of a mid-F star. We model the response of a modern Earth-like exoplanet's upper atmosphere to the heightened X-ray and extreme ultraviolet radiation within the habitable zone of Procyon A. These models indicate that this planet would not experience significant atmospheric escape. We simulate observations of the Ly$α$ transit signal of this exoplanet with the Hubble Space Telescope (HST) and the Habitable Worlds Observatory (HWO). While marginally detectable with HST, we find that H I Ly$α$ transits of potentially habitable exoplanets orbiting high radial velocity F-type stars could be observed with HWO for targets up to 150 pc away.
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Submitted 9 August, 2023;
originally announced August 2023.
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Disentangling Stellar and Airglow Emission Lines from HST-COS Spectra
Authors:
Fernando Cruz Aguirre,
Allison Youngblood,
Kevin France,
Vincent Bourrier
Abstract:
H I Ly$α$ (1215.67 Å) and the O I triplet (1302.17, 1304.86, and 1306.03 Å) are bright far-ultraviolet (FUV) emission lines that trace the stellar chromosphere. Observations of stellar Ly$α$ and O I using the Hubble Space Telescope's (HST) most sensitive FUV spectrograph, the Cosmic Origins Spectrograph (COS), are contaminated with geocoronal emission, or airglow. This study demonstrates that airg…
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H I Ly$α$ (1215.67 Å) and the O I triplet (1302.17, 1304.86, and 1306.03 Å) are bright far-ultraviolet (FUV) emission lines that trace the stellar chromosphere. Observations of stellar Ly$α$ and O I using the Hubble Space Telescope's (HST) most sensitive FUV spectrograph, the Cosmic Origins Spectrograph (COS), are contaminated with geocoronal emission, or airglow. This study demonstrates that airglow emission profiles as observed by COS are sufficiently stable to create airglow templates which can be reliably subtracted from the data, recovering the underlying stellar flux. We developed a graphical user interface to implement the airglow subtraction on a sample of 171 main sequence F, G, K, and M-type dwarfs from the COS data archive. Correlations between recovered stellar emission and measures of stellar activity were investigated. Several power law relationships are presented for predicting the stellar Ly$α$ and O I emission. The apparent brightness of the stellar emission relative to the airglow is a critical factor in the success or failure of an airglow subtraction. We developed a predictor for the success of an airglow subtraction using the signal-to-noise ratio (SNR) of the nearby chromospheric emission line Si III (1206.51 Å). The minimum attenuated Ly$α$ flux which was successfully recovered is 1.39$\times$10$^{-14}$ erg cm$^{-2}$ s$^{-1}$, and we recommend this as a minimum flux for COS Ly$α$ recoveries.
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Submitted 20 January, 2023;
originally announced January 2023.