GeminiFocus 2016 Year in Review | Page 22

This 2016 Year-in-Review highlights the innovative science being done by the Gemini user community .
January 2017
Figure 1 .
The top panel shows the spectrum of KH 15D during its “ bright ” phase , when the amount of direct starlight was greatest . The middle spectrum (“ intermediate ” phase ) was taken when star B was just below the edge of the ring . Both spectra in the bottom panel were obtained during “ faint ” phases from two different cycles , when both stars were near periastron and the contribution from starlight was minimized .
The spectrum from November has been offset by 1.5x10 -15 W m -2 μm -1 for comparison to the data from December .
Gemini staff contributions

Science Highlights

This 2016 Year-in-Review highlights the innovative science being done by the Gemini user community .
January 2017
Unscrambling a Complex Young Stellar System
Nicole Arulanantham of Wesleyan University ( Middletown , Connecticut ) and colleagues used the Gemini Near-InfraRed Spectrograph ( GNIRS ) on the Gemini North telescope to target the binary T Tauri system V582 Mon ( KH 15D ) — two K-type stars in a circumbinary ring that is inclined to the binary ’ s orbit .
The team obtained data at three different orientations of the system ’ s two young stars ( Figure 1 ), allowing them to study several key aspects of this complicated system — including characterizing the photosphere and magnetosphere of the companion star ( B ), exploring a jet of material associated with a bipolar outflow , and probing the scattering properties of its circumbinary ring . The research uncovered an excess of nearinfrared radiation that is possibly the signature of a self-luminous 10-Jupiter-mass planet . While this unresolved planet displays the expected excess in infrared radiation , as well as a 2-micron spectral feature that may be due to methane or ammonia , other anticipated signs of these two compounds went undetected in the observations . The team ’ s spectroscopic observations also indicate that a mixture of water and methane ice grains lie within the circumbinary ring — close enough to the primary stars that the frozen methane must be shielded by dust from direct radiation .
Finally , in addition to determining that star B is an early K-type subgiant , the research revealed variable helium I emission in star B ’ s magnetosphere due to ongoing mass accretion . The
20 GeminiFocus January 2017 | 2016 Year in Review