Spectral Typing of Late-Type Stellar Companions to Young Stars From Low-Dispersion Near-Infrared Integral Field Unit Data

Abstract

We used the Project 1640 near-infrared coronagraph and integral field spectrograph to observe 19 young solartype stars. Five of these stars are known binary stars and we detected the late-type secondaries and were able to measure their JH spectra with a resolution of R ∼ 30. The reduced, extracted, and calibrated spectra were compared to template spectra from the IRTF spectral library. With this comparison, we test the accuracy and consistency of spectral-type determination with the low-resolution near-infrared spectra from P1640. Additionally, we determine effective temperature and surface gravity of the companions by fitting synthetic spectra calculated with the PHOENIX model atmosphere code. We also present several new epochs of astrometry of each of the systems. Together, these data increase our knowledge and understanding of the stellar make up of these systems. In addition to the astronomical results, the analysis presented helps validate the Project 1640 data reduction and spectral extraction processes and the utility of low-resolution, near-infrared spectra for characterizing late-type companions in multiple systems.

Reconnaissance of the Hr 8799 Exosolar System. I. Near-Infrared Spectroscopy

“…We note, however, that Project 1640 has published numerous spectra of much brighter companions (ones that do not require speckle suppression to detect) and these are all consistent with other methods of near-IR spectroscopy. See, for example, Zimmerman et al (2010), Hinkley et al (2010Hinkley et al ( , 2011b, Roberts et al (2012), Pueyo et al (2012b) and Hinkley et al (2013). In addition, a Project 1640 disc-integrated spectrum of Titan agrees with other published spectra in this wavelength range, , and e components using the S4 algorithm.…”

“…The final spectra are obtained by multiplying the results from the previous step with this stellar spectrum. Note that this procedure for spectral calibration is slightly different than in earlier Project 1640 results presented in Hinkley et al (2010) and Roberts et al (2012). Those relied on the ratio of aperture photometry estimates of both the PSF cores and companion.…”

“…Those relied on the ratio of aperture photometry estimates of both the PSF cores and companion. As a sanity check, we conducted an analysis analogous to Hinkley et al (2010) and Roberts et al (2012): we used the relevant reduced images selected in step 2 and conducted step 3. By projecting un-occulted PSFs onto the relevant principal components and using aperture photometry to calibrate the self-subtraction, we computed the spectral calibration using aperture photometry of un-occulted images.…”

Know the Star, Know the Planet. V. Characterization of the Stellar Companion to the Exoplanet Host Star Hd 177830

“…To create a spectrum of the stellar companion, we performed aperture photometry on the images with sufficient signal-tonoise ratio in the P1640 data cube. We used the same techniques that we have used in our previous papers (e.g., Hinkley et al 2010;Zimmerman et al 2010;Roberts et al 2012). This was done with the aper.pro routine which is part of the IDL astrolib 14 and is an adaptation of DAOphot (Stetson 1987).…”

Project 1640: the world's first ExAO coronagraphic hyperspectral imager for comparative planetary science

“…For example, we have applied this technique applied to the early M-dwarf companion to HD 129333. 44 With these models and the search algorithm, a solution for each object can be found relatively quickly. We are currently expanding the algorithm to include other parameters in the search space, such as metallicity.…”