All posts by WebMaster

KELT-9 b optical Mg I triplet detected

PEPSI has detected the optical Mg I triplet at 7.8-sigma in the extended atmosphere of the ultra-hot Jupiter KELT-9 b. Constraints are placed on the density and radial extent of the excited hydrogen envelope.
Average line profiles for the Mg triplet lines of the Kelt-9 b atmosphere.
Average line profiles for the Mg triplet lines of the Kelt-9 b atmosphere. ST is the ratio stellar spectrum in transit divided by stellar spectrum out of transit. Possible contaminating atomic transitions are marked with vertical red lines. Spectral resolution R is 50,000.
  Read more: Cauley et al., https://arxiv.org/abs/1810.05776

AIP press release on PEPSI

First PEPSI data release

9 January 2018. The Potsdam Echelle Polarimetric and Spectroscopic Instrument (PEPSI) at the Large Binocular Telescope (LBT) in Arizona released its first batch of high-spectral resolution data to the scientific community. In a series of three papers in the European journal Astronomy & Astrophysics, the PEPSI team presents a new spectral atlas of the Sun, a total of 48 atlases of bright benchmark stars, and a detailed analysis of the chemical abundances of the 10-billion year old planet-system host Kepler-444.

Read more on the AIP website.

Kelt-21b: A hot Jupiter transiting the rapidly-rotating metal-poor late-A primary of a likely hierarchical triple system

Detection of the line profile perturbations confirmed that the planet candidate Kelt-21b does indeed transit its rapidly rotating host star. Furthermore, the motion of the line profile perturbation across the line profile during the transit diagnosted the spin-orbit misalignment, which is the angle between the stellar spin and planetary orbital angular momentum vectors projected onto the plane of the sky.

Kelt-21b
The Doppler tomographic PEPSI data for KELT-21. Time is from bottom up. Vertical lines mark the center of the line profile at v=0 and the edges at v = v sin i, a horizontal line shows the time of mid-transit, and the four small crosses depict the times of first through fourth contacts.

 

Read more: Johnson et al. 2018, AJ, 2018, 155, 100

News from the mountain: Open-shutter record at LBTO

During the first use of PEPSI-POL for science, we achieved a shutter-open-time of 91% during the night October 13/14, 2017. “Open-shutter time” is the time when photons are being collected on an instrument’s detector for later scientific use. As far as we know this is by far the highest at LBTO so far. The total available observing time from twilight to twilight on October 13/14 was 9 hours and 42 minutes of which 8 hours and 50 minutes were used to expose five different targets.

More pictures are here:

Posters presented at the 2nd LBT users meeting in Florence on June 20-23, 2017.

Polarimeters saw first light, LBT gets polarized

The installation of PEPSI at the LBT was completed on September 6th when both its polarimeters were mounted in the straight foci of the LBT. During the night of September 10, 2017 the telescope was pointed to the magnetic standard star gamma Equ and a series of integrations in circularly and linearly polarized light were obtained. These spectra have a spectral resolution of R=120,000, covered four wavelength regions in the optical (two always simultaneously) and reached a S/N ratio of up to 600:1 in 6 min integrations. The telescope was just tracking and not guiding yet nor were the wavefront sensors actively collimating the telescopes. The image quality was controlled by eye (by John Hill remotly from Tucson). Because the polarimeters for each of the LBT telescopes are identical and modular in design, circular and linear polarization may be obtained simultaneously. We used the SX side for circular and the DX side for linear polarization. A total of 12 exposures were obtained.

Image gallery

Partial solar eclipse observed by SDI

August 21, 2017. The partial solar eclipse was observed at Mt.Graham in Arizona remotely from AIP with the Solar Disk Integrated Telescope (SDI) which guides on the Sun and feeds the light into the PEPSI high-resolution spectrograph in the pier of the LBT telescope. The partial eclipse began on 09:16 MST and ended at 12:03 MST.

One hundred spectra were obtained during the course of the eclipse in two wavelength regions 422-477 and 536-628 nm with the resolving power 270 000 (1100 m/s in radial velocity per resolution element). The spectra obtained are highly dynamic as the area of the line formation changes, hence, the shape of the lines is slightly alternating. We perform analysis of the Sodium D1 line 589.59 nm which is formed in the lower chromosphere of the Sun above 500 km of its photosphere. Its bisector (i.e. the central wavelength at different depths of the line profile) shows large changes in the line core which is formed in the higher chromospheric layers.