The Polstar High Resolution Spectropolarimetry MIDEX Mission

Scowen, Paul A.; Gayley, K. G.; Neiner, C.; Vasudevan, Gopal; Woodruff, Robert A.; Ignace, Richard; Casini, R.; Hull, Tony; Nordt, Alison; Stahl, H. Philip

doi:10.1117/12.2594267

Cited by 11 publications

(4 citation statements)

References 17 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…For all science cases, excellent control of instrumental systematics (at a level of ∼ 0.1% in polarization) is necessary. The Polstar mission (Scowen et al 2021(Scowen et al , 2022 has been designed to provide the observing capabilities to accomplish this broad set of interstellar medium science objectives.…”

Section: • Clarifying the Origin Of High Polarization Efficiencymentioning

confidence: 99%

Ultraviolet spectropolarimetry with polstar: interstellar medium science

Andersson

Clayton

Doney

et al. 2022

Astrophys Space Sci

View full text Add to dashboard Cite

Continuum polarization over the UV-to-microwave range is due to dichroic extinction (or emission) by asymmetric, aligned dust grains. Scattering can also be an important source of polarization, especially at short wavelengths. Because of both grain alignment and scattering physics, the wavelength dependence of the polarization, generally, traces the size of the aligned grains. Similarly because of the differing wavelength dependencies of dichroic extinction and scattering polarization, the two can generally be reliably separated. Ultraviolet (UV) polarimetry therefore provides a unique probe of the smallest dust grains (diameter$< 0.09~\upmu \text{m}$ < 0.09 μm ), their mineralogy and interaction with the environment. However, the current observational status of interstellar UV polarization is very poor with less than 30 lines of sight probed. With the modern, quantitative and well-tested, theory of interstellar grain alignment now available, we have the opportunity to advance the understanding of the interstellar medium (ISM) by executing a systematic study of the UV polarization in the ISM of the Milky Way and near-by galaxies. The Polstar mission will provide the sensitivity and observing time needed to carry out such a program (probing hundreds of stars in the Milky Way and dozens of stars in the LMC/SMC), addressing questions of dust composition as a function of size and location, radiation- and magnetic-field characteristics as well as unveiling the carrier of the 2175 Å extinction feature. In addition, using high-resolution UV line spectroscopy Polstar will search for and probe the alignment of, and polarization from, aligned atoms and ions - so called “Ground State Alignment”, a potentially powerful new probe of magnetic fields in the diffuse ISM.

show abstract

Section: • Clarifying the Origin Of High Polarization Efficiencymentioning

confidence: 99%

Ultraviolet spectropolarimetry with polstar: interstellar medium science

Andersson

Clayton

Doney

et al. 2022

Astrophys Space Sci

View full text Add to dashboard Cite

show abstract

“…A single observation in either channel always includes six subexposures that cycle through the waveplate positions, providing the information needed to extract the Stokes parameters (I, Q, U, V) and enabling spectropolarimetry. Further details are given in Scowen et al (2021). Observations in both channel 1 and 2 can be leveraged to determine certain still-unknown properties of the Be and Bn populations.…”

Section: Proposed Uv Observationsmentioning

confidence: 99%

Ultraviolet Spectropolarimetry with Polstar: on the origin of rapidly rotating B stars

Jones¹,

Labadie-Bartz²,

Nazé³

et al. 2021

Preprint

View full text Add to dashboard Cite

The proposed MIDEX mission, Polstar, will provide high resolution UV spectroscopy and spectropolarimetry and offers a unique opportunity to study massive stars in this wavelength range with unprecedented detail. We demonstrate that these observations will provide critical new knowledge of several types of massive stars (specifically the B-emission stars and the Bn stars). We will determine accurate stellar parameters including their rotation rates and variation of surface temperature associated with stellar oblateness. Our work will allow us to detect binary companions and determine binary orbital properties. Binary population synthesis predictions will allow us to determine the fraction of these stars that are spun up due to binary interaction compared to single star evolution. These rapidly rotating stars have the potential to probe mass loss and the mixing of chemical elements which affects their evolution and ultimately the evolution of their surroundings.

show abstract

“…There are currently several missions under development at NASA Goddard Space Flight Center (GSFC) that provide wavelength coverage below 200 nm for a variety of applications that are sensitive to the intrinsic polarization of the reflective surfaces in the observatory and instrument designs [1]. As an example, the Habitable World Observatory (HWO) mission concept require mirrors that are intended to relay light to high-resolution coronagraphs for direct imaging of exoplanets, but that requires exquisite knowledge of the differential polarization at the point of reflection.…”

Section: Introductionmentioning

confidence: 99%

“…The scientific goals of HWO using polarization are based at this time on the portfolio defined by the Pollux instrument on LUVOIR-A, and involves mapping mass loss from massive stars, the physics of the emission line regions around AGN, the nature of the interstellar medium energy budget and mechanisms for grain alignment, to mention a few. In addition, for mission concepts dedicated to UV polarimetry, especially spectropolarimetry, like Polstar [1] a fundamental understanding of the polarization properties of mirror coatings is necessary for instrumental polarization for calibrationthat mission will seek to understand the impact of stellar rotation and angular momentum loss on the evolution of massive stars, which drives both the cycle of star and planet formation and the evolution of galaxies as a whole Paul Scowen dixit [2].…”

Section: Introductionmentioning

confidence: 99%

Linear polarizer design for application in the far-ultraviolet spectral range

Batkis,

Quijada,

Scowen

et al. 2023

UV/Optical/IR Space Telescopes and Instruments: Innovative Technologies and Concepts XI

View full text Add to dashboard Cite

New mission concepts that are under consideration by NASA call for the design and implementation of Far Ultraviolet (FUV) polarizer technologies that have not been developed yet. A team that includes members from the NASA Goddard Space Flight Center (GSFC), Arizona State University (ASU), and Woodruff Consulting, worked on the design and development of a polarizer design that produce very high extinction ratios in the FUV spectral range (100-200 nm). This polarizer consists of reflecting light through a series of mirrors from a combination of two silicon carbide (SiC) and two lithium fluoride (LiF) crystals positioned at angles of incidence (relative to surface normal) close to the average LiF Brewster’s angle in the FUV. The output is a highly linearly polarized beam. This polarizer concept was fabricated and tested in the existing McPherson 225 Vacuum Ultraviolet (VUV) spectrometer located in the Optics Branch at NASAGSFC. Initial testing using a MgF2 crystal at the Brewster’s angle as an analyzer has shown that this design can produce state-of-the-art extinction ratios at the Hydrogen Lyman-Alpha (Ly-α) wavelength of 121.6 nm, and that the measured extinction ratio of the two crossed polarizers, ≈114, is mostly limited by the MgF2 analyzer. A polarizer with such a performance at this wavelength has never been reported and it signifies a breakthrough in FUV polarization technology. The levels of effectiveness paired with the polarizer’s compact design allows for a new polarizer capability that would one day be implemented in a future FUV spectropolarimetry space mission.

show abstract

The Polstar High Resolution Spectropolarimetry MIDEX Mission

Cited by 11 publications

References 17 publications

Ultraviolet spectropolarimetry with polstar: interstellar medium science

Ultraviolet spectropolarimetry with polstar: interstellar medium science

Ultraviolet Spectropolarimetry with Polstar: on the origin of rapidly rotating B stars

Linear polarizer design for application in the far-ultraviolet spectral range

Contact Info

Product

Resources

About