Inner warm disk of Class I ESO Hα 279a revealed by Na I and CO overtone emission lines A-Ran Lyo, Jongsoo Kim, Jae-Joon Lee, Kyoung-Hee Kim, Jihyun Kang, Do-Young Byun, Gregory Mace, Kimberly R. Sokal, Chan Park, Moo-Young Chun, Heeyoung Oh, Young Sam Yu, Jae Sok Oh, Ueejeong Jeong, Hwihyun Kim, Soojong Pak, Narae Hwang, Byeong-Gon Park, Sungho Lee, Kyle Kaplan, Hye-In Lee, Huynh Anh Nguyen Le, and Daniel Jaffe IGRINS (Immersion GRating INfrared Spectrometer) R = λ/Δλ = 45,000 Simultaneous observation of H & K Δv ~ 7 km/s at 2.3 μm Mounted on 2.7m MacDonald telescope Current: 4.3m DCT (discovery channel telescope) IGRINS mounted on 2.7m MacDonald Telescope

(Andrews et al. 2016, ApJL, 820, L40)

Inner disk : main controller of the final structure of planetary systems

ESO Hα 279a Class I YSO (Young stellar object) in Serpens Molecular Clouds d = 429 pc (Dzib et al. 2010, 2011) M ~ 1.5 M⊙

H-band

K-band

1. Inner warm CO gas disk Geometrically flat Keplerian rotational CO disk with the power law distributions in density and temperature Density index p = 1.5, temperature index q= 0.5 Nin = 2.275×1018/cm2; Tin = 4600; Vin sini = 55.5 km/s; Vout sini = 15.0 km/s R ~ 0.22 – 3.00 AU at M=1.5M⊙ at the disk inclination of 45°

2. Inner warm Na I keplerian rotational disk Power index in the density distribution p = 1.5 (p = 2.0) R1/R2 = 0.03 (0.08) V2 sini = 30.53 km/s (28.42 km/s) R ~ 0.02 – 0.72 AU (0.07 – 0.83 AU)

3. Extinction Stellar properties – Disk properties Extinction – Stellar properties, such as mass, age, etc. Av = 9.6 mag (Class II/III YSOs) at Serpens star forming region Brackett series: Av = 9.7 mag case B model recombination emissivities at the condition of T=7500 K and ne=108 cm−3 (Storey & Hummer 1995)

4. Disk Accretion rate Ṁacc ∼ 2 – 10 × 10-7 M⊙/yr FK ~ 4.63×10-10 erg sec-1 cm-2 μm-1 EW = -16.39 Å It follows the derived relationships between the stellar masses and the mass accretion rates of Ṁacc ∝ M2.1 (Muzerolle et al. 2005)

Class I ESO Hα 279a we detect emission lines originating from the accretion channel flow, jet, and inner disk : hydrogen Brackett series recombination, [Fe II], [Fe III], [Fe IV], Ca I, Na I, H2, H2O and CO overtone emission lines. CO overtone emission lines originated in the keplerian disk in the range between 0.22 AU and 3.00 AU. Na I emission lines originate between 0.04 AU and 0.78 AU we confirm that the mean extinction value of AV = 9.6 mag for Class II/III YSOs in the Serpens region also matches our estimation towards ESO Hα 279a. Ṁ = 2 ∼ 10 × 10−7 M⊙ yr−1 from the measured Brγ emission luminosity of 1.78×1031 erg s−1.