Optical spectroscopic and polarization properties of 2011 outburst of the recurrent nova T Pyxidis

We study the spectroscopic and ionized structural evolution of T Pyx during its 2011 outburst, and also study the variation in degree of polarization during its early phase. Optical spectroscopic data of this system obtained from day 1.28--2415.62 since discovery, and optical, broadband imaging polarimetric observations obtained from day 1.36--29.33 during the early phases of the outburst are used in the study. The physical conditions and the geometry of the ionized structure of the nova ejecta has been modelled for a few epochs using the photo-ionization code, CLOUDY in 1D and pyCloudy in 3D. The spectral evolution of the nova ejecta during its 2011 outburst is similar to that of the previous outbursts. The variation in the line profiles is seen very clearly in the early stages due to good coverage during this period. The line profiles vary from P-Cygni (narrower, deeper and sharper) to emission profiles which are broader and structured, which later become narrower and sharper in the late post-outburst phase. The average ejected mass is estimated to be $7.03\, \times\, 10^{-6}\, M_{\odot}$. The ionized structure of the ejecta is found to be a bipolar conical structure with equatorial rings, with a low inclination angle of $14.75^\circ\, \pm\, 0.65^\circ$.Comment: 14 pages, 12 figures, accepted in A&

NMF-based GPU accelerated coronagraphy pipeline

We present a generalized Non-negative factorization (NMF)-based data reduction pipeline for circumstellar disk and exoplanet detection. By using an adaptable pre-processing routine that applies algorithmic masks and corrections to improper data, we are able to easily offload the computationally-intensive NMF algorithm to a graphics processing unit (GPU), significantly increasing computational efficiency. NMF has been shown to better preserve disk structural features compared to other post-processing approaches and has demonstrated improvements in the analysis of archival data. The adaptive pre-processing routine of this pipeline, which automatically aligns and applies image corrections to the raw data, is shown to significantly improve chromatic halo suppression. Utilizing HST-STIS and JWST-MIRI coronagraphic datasets, we demonstrate a factor of five increase in real-time computational efficiency by using GPUs to perform NMF compared to using CPUs. Additionally, we demonstrate the usefulness of higher numbers of NMF components with SNR and contrast improvements, which necessitates the use of a more computationally efficient approach for data reduction

Estimation of polarization aberrations and its effect on the point spread function of the Thirty Meter Telescope

The Thirty Meter Telescope (TMT) is a future generation telescope proposed to be located in Mauna Kea, Hawaii or in La Palma in the Canary Islands. The telescope will have a segmented primary and an inclined tertiary mirror. The segmentation of the primary mirror and the inclination in the tertiary mirror can introduce significant polarization aberrations. Typically, the polarization aberrations, introduced due to the mirror coating and the high incident angles cause small modifications to the Point Spread Function (PSF). Here, we perform the polarization ray tracing for TMT using the optical design software Zemax for different input polarizations for a point source (on-axis). We calculate the diattenuation and retardance aberration maps for all the three mirrors of TMT. The coating induced astigmatism obtained from the retardance of the primary and secondary mirror is found to be of the order of 0.048 radians, whereas, the polarization induced tilt by the retardance of the tertiary mirror is in the order of 0.29 radians. The Jones pupil maps are estimated at two of the instrument ports, Wide Field Optical Spectrograph (WFOS) and Narrow Field Infrared Adaptive Optics System (NFIRAOS).The Amplitude Response Matrix (ARM) estimated at the WFOS port show the presence of ghost PSF's. The magnitude of the ghost PSF components is of the order of 2.5 x 10^(-5) at 1μm at WFOS port. The ARM and the Point Spread Matrix (PSM) are estimated at the focus of the NFIRAOS instrument. The Stokes PSF is shown for horizontal and vertical polarization as inputs. The Huygen's point spread function obtained from Zemax shows the variations in FWHM for unpolarized and polarized inputs. These estimations would help in the design aspects of a high contrast imaging instrument for the TMT in the future

Polarimetric modeling and assessment of science cases for Giant Magellan Telescope-Polarimeter (GMT-Pol)

Polarization observations through the next-generation large telescopes will be invaluable for exploring the magnetic fields and composition of jets in AGN, multi-messenger transients follow-up, and understanding interstellar dust and magnetic fields. The 25m Giant Magellan Telescope (GMT) is one of the next-generation large telescopes and is expected to have its first light in 2029. The telescope consists of a primary mirror and an adaptive secondary mirror comprising seven circular segments. The telescope supports instruments at both Nasmyth as well as Gregorian focus. However, none of the first or second-generation instruments on GMT has the polarimetric capability. This paper presents a detailed polarimetric modeling of the GMT for both Gregorian and folded ports for astronomical B-K filter bands and a field of view of 5 arc minutes. At 500nm, The instrumental polarization is 0.1% and 3% for the Gregorian and folded port, respectively. The linear to circular crosstalk is 0.1% and 30% for the Gregorian and folded ports, respectively. The Gregorian focus gives the GMT a significant competitive advantage over TMT and ELT for sensitive polarimetry, as these telescopes support instruments only on the Nasmyth platform. We also discuss a list of polarimetric science cases and assess science case requirements vs. the modeling results. Finally, we discuss the possible routes for polarimetry with GMT and show the preliminary optical design of the GMT polarimeter.Comment: 13 pages, 5 figures,SPIE Optics + Photonics 2023 conference proceeding, Paper no 12690-2

Estimation of polarization aberrations and their effect on the coronagraphic performance for future space telescopes

A major goal of proposed future space observatories, such as the Habitable World Observatory, is to directly image and characterize Earth-like planets around Sun-like stars to search for habitability signatures requiring the starlight suppression (contrast) of 1e-10. One of the significant aspects affecting this contrast is the polarization aberrations generated from the reflection from mirror surfaces. The polarization aberrations are the phase-dependent amplitude and phase patterns originating from the Fresnel reflections of the mirror surfaces. These aberrations depend on the angle of incidence and coating parameters of the surface. This paper simulates the polarization aberrations for an on-axis and off-axis TMA telescope of a 6.5 m monolithic primary mirror. We analyze the polarization aberrations and their effect on the coronagraphic performance for eight different recipes of mirror coatings for Astronomical filter bands g-I: three single-layer metal coatings and five recipes of protective coatings. First, the Jones pupils are estimated for each coating and filter band using the polarization ray tracing in Zemax. Then, we propagate these Jones pupils through a Vector Vortex Coronagraph and Perfect Coronagraphs using hcipy, a physical optics-based simulation framework. The analysis shows that the two main polarization aberrations generated from the four mirrors are the retardance-defocus and retardance-tilt. The simulations also show that the coating plays a significant role in determining the strength of the aberrations. The bare/oxi-aluminum and Al+18nm LiF coating outperforms all the other coatings by one order of magnitude.Comment: 13 pages, 11 figures, SPIE Optics+Photonics 2023 proceeding, Paper no: 12680-2

Analytical Modelling of Thirty Meter Telescope Optics Polarization

The polarization introduced due to Thirty Meter Telescope (TMT) optics is calculated using an analytical model. Mueller matrices are also generated for each optical element using Zemax, based on which the instrumental polarization due to the entire system at the focal plane is estimated and compared with the analytical model. This study is significant in the estimation of the telescope sensitivity and also has great implications for future instruments

RZ Piscium Hosts a Compact and Highly Perturbed Debris Disk

RZ Piscium (RZ Psc) is well-known in the variable star field because of its numerous, irregular optical dips in the past five decades, but the nature of the system is heavily debated in the literature. We present multiyear infrared monitoring data from Spitzer and WISE to track the activities of the inner debris production, revealing stochastic infrared variability as short as weekly timescales that is consistent with destroying a 90-km-size asteroid every year. ALMA 1.3 mm data combined with spectral energy distribution modeling show that the disk is compact ($\sim$0.1--13 au radially) and lacks cold gas. The disk is found to be highly inclined and has a significant vertical scale height. These observations confirm that RZ Psc hosts a close to edge-on, highly perturbed debris disk possibly due to migration of recently formed giant planets which might be triggered by the low-mass companion RZ Psc B if the planets formed well beyond the snowlines.Comment: 16 pages, 5 figures, accepted for publication in Ap

The space coronagraph optical bench (SCoOB): 2. wavefront sensing and control in a vacuum-compatible coronagraph testbed for spaceborne high-contrast imaging technology

The 2020 Decadal Survey on Astronomy and Astrophysics endorsed space-based high contrast imaging for the detection and characterization of habitable exoplanets as a key priority for the upcoming decade. To advance the maturity of starlight suppression techniques in a space-like environment, we are developing the Space Coronagraph Optical Bench (SCoOB) at the University of Arizona, a new thermal vacuum (TVAC) testbed based on the Coronagraphic Debris Exoplanet Exploring Payload (CDEEP), a SmallSat mission concept for high contrast imaging of circumstellar disks in scattered light. When completed, the testbed will combine a vector vortex coronagraph (VVC) with a Kilo-C microelectromechanical systems (MEMS) deformable mirror from Boston Micromachines Corp (BMC) and a self-coherent camera (SCC) with a goal of raw contrast surpassing $10^{-8}$ at visible wavelengths. In this proceedings, we report on our wavefront sensing and control efforts on this testbed in air, including the as-built performance of the optical system and the implementation of algorithms for focal-plane wavefront control and digging dark holes (regions of high contrast in the focal plane) using electric field conjugation (EFC) and related algorithms.Comment: 7 pages, 5 figures, SPIE Astronomical Telescopes and Instrumentation 202

Polarization aberrations in next-generation giant segmented mirror telescopes (GSMTs) I. Effect on the coronagraphic performance

Next-generation large segmented mirror telescopes are expected to perform direct imaging and characterization of Earth-like rocky planets, which requires contrast limits of $10^{-7}$ to $10^{-8}$ at wavelengths from I to J band. One critical aspect affecting the raw on-sky contrast are polarization aberrations arising from the reflection from the telescope's mirror surfaces and instrument optics. We simulate the polarization aberrations and estimate their effect on the achievable contrast for three next-generation ground-based large segmented mirror telescopes. We performed ray-tracing in Zemax and computed the polarization aberrations and Jones pupil maps using the polarization ray-tracing algorithm. The impact of these aberrations on the contrast is estimated by propagating the Jones pupil maps through a set of idealized coronagraphs using hcipy, a physical optics-based simulation framework. The optical modeling of the giant segmented mirror telescopes (GSMTs) shows that polarization aberrations create significant leakage through a coronagraphic system. The dominant aberration is retardance defocus, which originates from the steep angles on the primary and secondary mirrors. The retardance defocus limits the contrast to $10^{-5}$ to $10^{-4}$ at 1 $\lambda/D$ at visible wavelengths, and $10^{-5}$ to $10^{-6}$ at infrared wavelengths. The simulations also show that the coating plays a major role in determining the strength of the aberrations. Polarization aberrations will need to be considered during the design of high-contrast imaging instruments for the next generation of extremely large telescopes. This can be achieved either through compensation optics, robust coronagraphs, specialized coatings, calibration, and data analysis approaches or by incorporating polarimetry with high-contrast imaging to measure these effects.Comment: 18 pages, 12 figures, Accepted in Astronomy & Astrophysics manuscript no. aa45651-2

The Space Coronagraph Optical Bench (SCoOB): 1. Design and Assembly of a Vacuum-compatible Coronagraph Testbed for Spaceborne High-Contrast Imaging Technology

The development of spaceborne coronagraphic technology is of paramount importance to the detection of habitable exoplanets in visible light. In space, coronagraphs are able to bypass the limitations imposed by the atmosphere to reach deeper contrasts and detect faint companions close to their host star. To effectively test this technology in a flight-like environment, a high-contrast imaging testbed must be designed for operation in a thermal vacuum (TVAC) chamber. A TVAC-compatible high-contrast imaging testbed is undergoing development at the University of Arizona inspired by a previous mission concept: The Coronagraphic Debris and Exoplanet Exploring Payload (CDEEP). The testbed currently operates at visible wavelengths and features a Boston Micromachines Kilo-C DM for wavefront control. Both a vector vortex coronagraph and a knife-edge Lyot coronagraph operating mode are under test. The optics will be mounted to a 1 x 2 meter pneumatically isolated optical bench designed to operate at 10^-8 torr and achieve raw contrasts of 10^-8 or better. The validation of our optical surface quality, alignment procedure, and first light results are presented. We also report on the status of the testbed's integration in the vaccum chamber.Comment: 14 pages, 9 figure