The upgrade of a high dispersion spectro-polarimeter, VESPolA: new circular polarimetry mode and extremely high resolution mode

Takayuki Arasaki; Yuji Ikeda; Nakamichi Akika; Hideyo Kawakita

doi:10.1117/12.2055700

28 July 2014 The upgrade of a high dispersion spectro-polarimeter, VESPolA: new circular polarimetry mode and extremely high resolution mode

Takayuki Arasaki, Yuji Ikeda, Nakamichi Akika, Hideyo Kawakita

Author Affiliations +

Proceedings Volume 9147, Ground-based and Airborne Instrumentation for Astronomy V; 914788 (2014) https://doi.org/10.1117/12.2055700
Event: SPIE Astronomical Telescopes + Instrumentation, 2014, Montréal, Quebec, Canada

Abstract

VESPolA is a high dispersion spectro-polarimeter, mounted on the 1.3m Araki telescope at Koyama Astronomical Observatory of Kyoto Sangyo University. It employs an echelle type spectrograph and a non-ripple super-achromatic half wave plate, resulting in the highly polarimetric accuracy of δP < 0.1% with the spectral resolution of R = 8,000 and a wide wavelength coverage of δλ = 150nm - 300nm in a single exposure. It is specialized for the 1-2 m class small telescope with Cassegrain focus. Because VESPolA can observed a dozen of polarization line profiles in the targets simultaneously, we can obtain complementary information on both the geometry and the velocity fields of the circumstellar envelope of variable stars, such as WR stars, Be stars, Herbig Ae/Be stars, T Tau stars, and so on. VESPolA has achieved the high accuracy of δP ~ {(0.05)² + (0.09)²P²}^1/2% with spectral resolution of R ~ 8,000 for liner polarization. Recently, a new scientific program, search for magnetic pole-shift of stars (Nakamichi et al. 20129), was accepted at the Koyama Astronomical Observatory. Therefore, we plan to add a new modes, a high resolution mode (R = 20,000) and a circular polarimetry mode for this study, to VESPolA. We employ an alumina (Al₂O₃) slit as the new slit for the high resolution mode to minimize the instrumental polarization generated at the edge of the slit. However, because the slit width should be very narrow (= 35μm), it is technically difficult to realize the smooth slit without burr or chipping. We are trying the various processing methods, machining, etching, laser cutting, and so on. The circular polarimetry mode can be realized with a new non-ripple super-achromatic quarter wave plate and the high precision rotary unit, which is located just below the existing the half wave plate unit. We will finish the update within 2015 and start the science observations.

Citation Download Citation

Takayuki Arasaki, Yuji Ikeda, Nakamichi Akika, and Hideyo Kawakita "The upgrade of a high dispersion spectro-polarimeter, VESPolA: new circular polarimetry mode and extremely high resolution mode", Proc. SPIE 9147, Ground-based and Airborne Instrumentation for Astronomy V, 914788 (28 July 2014); https://doi.org/10.1117/12.2055700

ACCESS THE FULL ARTICLE

INSTITUTIONAL
Select your institution to access the SPIE Digital Library.

SELECT YOUR INSTITUTION

PERSONAL
Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.

PERSONAL SIGN IN

No SPIE Account? Create one

PURCHASE THIS CONTENT

SUBSCRIBE TO DIGITAL LIBRARY

50 downloads per 1-year subscription

Members: $195

Non-members: $335 ADD TO CART

25 downloads per 1 - year subscription

Members: $145

Non-members: $250 ADD TO CART

PURCHASE SINGLE ARTICLE

Includes PDF, HTML & Video, when available