The BOES Spectropolarimeter for Zeeman Measurements of Stellar Magnetic Fields

Park

et al. 2015

A&A

Aims. This program originated as the north pole region extension of the established exoplanet survey using the 1.8 m telescope at Bohyunsan Optical Astronomy Observatory (BOAO). The aim of our paper is to find exoplanets in northern circumpolar stars with a precise radial velocity (RV) survey. Methods. We selected about 200 northern circumpolar stars with the following criteria: δ ≥ 70 • , 0.6 < B − V < 1.6, H scat < 0.05 mag, and 5.0 < m v < 7.0. The high-resolution, fiber-fed Bohyunsan Observatory Echelle Spectrograph (BOES) was used for the RV survey. Chromospheric activities, the H photometry, and line bisectors were analyzed to exclude other causes for the RV variations.Results. In 2010, we started to monitor the candidates and have completed initial screening for all stars for the past five years. We present the detection of four new exoplanets. Stars HD 11755, HD 12648, HD 24064, and 8 UMi all show evidence of giant planets in Keplerian motion. The companion to HD 11755 has a minimum mass of 6.5 M Jup in a 433-day orbit with an eccentricity of 0.19. HD 12648 is orbited by a companion with a minimum mass of 2.9 M Jup , a period of 133 days, and an eccentricity of 0.04. Weak surface activity was suspected in HD 24064. However, no evidence was found to be associated with the RV variations. Its companion has a minimum mass of 9.4 M Jup , a period of 535 days, and an eccentricity of 0.35. Finally, 8 UMi has a minimum mass of 1.5 M Jup and a period of 93 days with an eccentricity of 0.06.

Section: Observations and Data Reductionmentioning

confidence: 99%

Search for exoplanet around northern circumpolar stars

Park

et al. 2015

A&A

Monthly Notices of the Royal Astronomical Society

“…In addition, to be able to rule out instrumental artifacts, we also used data of the same targets collected by the BOES echelle spectrograph 3 (Kim et al 2007) attached to the 1.8m telescope of the Bohyunsan Observatory in Korea. This instrument can operate in three observational modes providing resolving powers of 30,000, 45,000 and 90,000 respectively.…”

Section: Observationsmentioning

confidence: 99%

Redshifted diffuse interstellar bands in the Orion OB1 association

Krełowski

Галазутдинов

Mulas

et al. 2015

The wavelength displacement of the Diffuse Interstellar Bands at 4502, 5705, 5780, 6284, and 7224Å with respect to the well known, narrow atomic/molecular interstellar lines (of Caii and Nai) have been measured in the spectra of the 2 Orion Trapezium stars HD 37022 and HD 37020, using the HARPS-N spectrograph, fed with the 3.5 m Telescopio Nazionale Galileo, and the BOES spectrograph, fed with the 1.8m Korean telescope. The red-shift is ∼25 km/s for all these DIBs. We discuss the various possible origins of this very peculiar wavelength shift in the light of the particular physical conditions in the Orion Trapezium. The above mentioned shift is seemingly absent in the DIBs at 6196 and 6993Å.

“…The timescale for these exposures (and polarimetric modulation) is often many minutes. For instance, there are several existing and planned fiber-fed instruments like ESPaDOnS, HARPSpol, BOES, PEPSI that are designed to deliver spectral resolutions above 50 000 and large one-shot wavelength coverage by using cross-dispersion (Semel et al 1993;Donati et al 1997Donati et al , 1999Piskunov et al 2011;Manset & Donati 2003;Snik et al 2011Snik et al , 2008Kim et al 2007;Strassmeier et al 2008). These instruments are not designed to measure continuum polarization but fairly reasonable measurement precision is possible under a range of circumstances 1 (Pereyra et al 2015).…”

Section: Spectropolarimetric Instruments Errors and Suppression Tecmentioning

confidence: 99%

Calibrating and stabilizing spectropolarimeters with charge shuffling and daytime sky measurements

Harrington

Kuhn

Nevin

2015

A&A

Well-calibrated spectropolarimetry studies at resolutions of R > 10 000 with signal-to-noise ratios (S/Ns) better than 0.01% across individual line profiles, are becoming common with larger aperture telescopes. Spectropolarimetric studies require high S/N observations and are often limited by instrument systematic errors. As an example, fiber-fed spectropolarimeters combined with advanced line-combination algorithms can reach statistical error limits of 0.001% in measurements of spectral line profiles referenced to the continuum. Calibration of such observations is often required both for cross-talk and for continuum polarization. This is not straightforward since telescope cross-talk errors are rarely less than ∼1%. In solar instruments like the Daniel K. Inouye Solar Telescope (DKIST), much more stringent calibration is required and the telescope optical design contains substantial intrinsic polarization artifacts. This paper describes some generally useful techniques we have applied to the HiVIS spectropolarimeter at the 3.7 m AEOS Telescope on Haleakala. HiVIS now yields accurate polarized spectral line profiles that are shot-noise limited to 0.01% S/N levels at our full spectral resolution of 10 000 at spectral sampling of ∼100 000. We show line profiles with absolute spectropolarimetric calibration for cross-talk and continuum polarization in a system with polarization cross-talk levels of essentially 100%. In these data the continuum polarization can be recovered to one percent accuracy because of synchronized charge-shuffling model now working with our CCD detector. These techniques can be applied to other spectropolarimeters on other telescopes for both night and daytime applications such as DKIST, TMT, and ELT which have folded non-axially symmetric foci.