IGRINS K-band High-Resolution Spectroscopy of the FU Ori Type Object 2MASS J06593158-0405277

ATel #6901; Tae-Soo Pyo (Subaru Telescope, NAOJ), Heeyoung Oh (Korea UST, KASI), In-Soo Yuk (KASI), Hwihyun Kim (KASI/UT Austin), C. J. Davis (Liverpool John Moores Univ.)
on 11 Jan 2015; 20:30 UT
Credential Certification: Tae-Soo Pyo (pyo@naoj.org)

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We report a part of K-band high resolution spectra (R ~ 40,000) of 2MASS J06593158-0405277 which was discovered recently by Maehara, Kojima, and Fujii (ATEL #6770). The spectra were obtained with IGRINS (Immersion GRating INfrared Spectrometer) mounted on the 2.7m Harlan J. Smith Telescope at McDonald Observatory on December 25.31 and 26.44, 2014 (UT). The total on-source exposure time was 400 s (100 x 4) for each night. The signal-to-noise ratio was 50 +/- 30. IGRINS covers both H- and K-bands simultaneously with a single exposure. The raw data were processed through the IGRINS pipeline software with the following steps: flat-fielding, sky-subtraction, spectrum extraction, and wavelength correction. We used IRAF packages for the sensitivity and telluric corrections with A0 type standard star. The Hydrogen recombination lines were removed from A0 standard star before the process. We corrected the heliocentric velocity of the observed spectra and did not correct the system velocity of the molecular cloud (Lynds 1650: ATEL #6862). Fig. 1 shows the normalized spectrum in the range of 2.3 - 2.32 micron where the CO first overtone band is dominant and mixed with H2O lines. It shows very similar pattern with FU Ori (1999) but not with V1515 Cyg (1999) in Hartmann, Hinkle, and Carvet (2004, ApJ, 609, 906). We found that the Br_gamma line shows absorption not emission (Fig. 2). The FWHM of the absorption is ~ 95 - 100 km/s. The line profile was almost symmetric at 21663.3 A on Dec. 25.31, 2014 UT. It shows a little asymmetric with the deepest point shifted to 21664.73 A on Dec. 26.44, 2014 UT. FU Ori, V1057 Cyg, V883 Ori, and L1551 IRS5 show the similar weak Br_gamma absorption, which can be only detected with high spectral resolution spectroscopy (Aspin et al. 2009, AJ, 137, 2968). We are preparing for a paper with the whole H- & K-band (1.48-2.45 micron) spectra in detail. IGRINS has been developed by KASI (Korea Astronomy and Space Science Institute) and University of Texas.

K-band spectra: 2.3-2.32 micron (Fig.1) and Br_gamma (Fig.2)