Discovery of Extremely Embedded X-ray Sources in the R Coronae Australis Star Forming Core

With the XMM-Newton and Chandra observatories, we detected two extremely embedded X-ray sources in the R Corona Australis (R CrA) star forming core, near IRS 7. These sources, designated as XB and XA, have X-ray absorption columns of ~3e23 cm-2 equivalent to AV ~180 mag. They are associated with the VLA centimeter radio sources 10E and 10W, respectively. XA is the counterpart of the near-infrared source IRS 7, whereas XB has no K-band counterpart above 19.4 mag. This indicates that XB is younger than typical Class I protostars, probably a Class 0 protostar or in an intermediate phase between Class 0 and Class I. The X-ray luminosity of XB varied between 29<log LX <31.2 ergs s-1 on timescales of 3-30 months. XB also showed a monotonic increase in X-ray brightness by a factor of two in 30 ksec during an XMM-Newton observation. The XMM-Newton spectra indicate emission from a hot plasma with kT ~3-4 keV and also show fluorescent emission from cold iron. Though the X-ray spectrum from XB is similar to flare spectra from Class I protostars in luminosity and temperature, the light curve does not resemble the lightcurves of magnetically generated X-ray flares because the variability timescale of XB is too long and because variations in X-ray count rate were not accompanied by variations in spectral hardness. The short-term variation of XB may be caused by the partial blocking of the X-ray plasma, while the month-long flux enhancement may be driven by mass accretion.Comment: 26 pages, 8 figures, To be published in ApJ in April 200

H2_2 Emission Nebulosity Associated with KH 15D

An H$_2$ emission filament is found in close proximity to the unique object KH 15D using the adaptive optics system of the Subaru Telescope. The morphology of the filament, the presence of spectroscopic outflow signatures observed by Hamilton et al., and the detection of extended H$_2$ emission from KH 15D by Deming, Charbonneau, & Harrington suggest that this filament arises from shocked H$_2$ in an outflow. The filament extends about 15" to the north of KH 15D.Comment: 11 pages, 3 figures, 1 table. Astrophysical Journal Letters, in pres

A Subarcsecond Companion to the T Tauri Star AS 353B

Adaptive optics imaging of the bright visual T Tauri binary AS 353 with the Subaru Telescope shows that it is a hierarchical triple system. The secondary component, located 5.6" south of AS 353A, is resolved into a subarcsecond binary, AS 353Ba and Bb, separated by 0.24". Resolved spectroscopy of the two close components shows that both have nearly identical spectral types of about M1.5. Whereas AS 353A and Ba show clear evidence for an infrared excess, AS 353Bb does not. We discuss the possible role of multiplicity in launching the large Herbig-Haro flow associated with AS 353A.Comment: AASTeXv5.0, 21 pages, 5 figures, Astronomical Journal, in pres

First Detection of NaI D lines in High-Redshift Damped Lyman-alpha Systems

A Near-infrared (1.18-1.35 micron) high-resolution spectrum of the gravitationally-lensed QSO APM 08279+5255 was obtained with the IRCS mounted on the Subaru Telescope using the AO system. We detected strong NaI D 5891,5897 doublet absorption in high-redshift DLAs at z=1.062 and 1.181, confirming the presence of NaI, which was first reported for the rest-frame UV NaI 3303.3,3303.9 doublet by Petitjean et al. This is the first detection of NaI D absorption in a high-redshift (z>1) DLA. In addition, we detected a new NaI component in the z=1.062 DLA and four new components in the z=1.181 DLA. Using an empirical relationship between NaI and HI column density, we found that all "components" have large HI column density, so that each component is classified as DLA absorption. We also detected strong NaI D absorption associated with a MgII system at z=1.173. Because no other metal absorption lines were detected in this system at the velocity of the NaI absorption in previously reported optical spectra (observed 3.6 years ago), we interpret this NaI absorption cloud probably appeared in the line of sight toward the QSO after the optical observation. This newly found cloud is likely to be a DLA based upon its large estimated HI column density. We found that the N(NaI)/N(CaII) ratios in these DLAs are systematically smaller than those observed in the Galaxy; they are more consistent with the ratios seen in the Large Magellanic Cloud. This is consistent with dust depletion generally being smaller in lower metallicity environments. However, all five clouds of the z=1.181 system have a high N(NaI)/N(CaII) ratio, which is characteristic of cold dense gas. We tentatively suggest that the host galaxy of this system may be the most significant contributor to the gravitational-lens toward APM 08279+5255.Comment: 22 pages, 6 Postscript figures, 3 tables, ApJ in press (Vol.643, 2 June 2006

Adaptive Optics Spectroscopy of the [Fe II] Outflows from HL Tauri and RW Aurigae

We present new results of [Fe II] 1.644-micron spectroscopy toward the jets from HL Tau and RW Aur carried out with the Subaru Telescope combined with the adaptive optics system. We observed the regions within 2" - 3" from the stars with the sub-arcsecond resolutions of 0."5 and 0."2 for HL Tau and RW Aur, respectively. In addition to the strong, high velocity emission extended along each jet, we detected a blueshifted low velocity emission feature seen as a wing or shoulder of the high velocity emission at each stellar position. Detailed analysis shows that the position-velocity diagrams (PVDs) of HL Tau and RW Aur show a characteristic similar to those of the cold disk wind and X-wind models in that the [Fe II] line width is broad in the vicinity of the stellar position and is narrower at the extended jet. A closer comparison suggests, however, that the disk wind model tends to have too large line width at the jet while the X-wind model has excess emission on the redshifted side at the stellar position. The narrow velocity width with symmetric line profiles of the observed high velocity emission supports an X-wind type model where the launching region is localized in a small radial range, while the low velocity emission located away from the star favors the presence of a disk wind. The [Fe II] emission from the HL Tau jet shows a gap of 0."8 between the redshifted jet and the star, indicating the presence of an optically thick disk of ~ 160 AU in radius. The [Fe II] emission from the RW Aur jet shows a marked drop from the redshifted peak at Y ~ -0."2 toward the star, suggesting that its disk radius is smaller than 40 AU.Comment: Accepted in the ApJ (October 2006, v649n2), AAS LaTEX macros v 5.2, Total 25 pages with 7 figure

Discovery of Extremely Embedded X-ray Sources in the R Coronae Australis Star Forming Core

We detected three extremely embedded X-ray sources in the R Corona Australis (R CrA) star forming core, IRS 7 region. Two weak X-ray sources are associated with the VLA centimeter radio sources 10E & W, whereas the third brightest source detected in the two XMM-Newton observations on March 2003 has no counterpart at any wavelengths. The large K-band upper-limit (19.4m) measured with the University of Hawaii 88-inch Telescope and strong absorption derived in X-rays (N(sub H) approx. 2.8 x 10(exp 23)/sq cm equivalent to A(sub v) approx. 180 m) indicate that the source is younger than typical Class I protostars, i.e. a Class 0 protostar or an intermittent phase between Class 0 and Class I protostars. The X-ray luminosity was less than one thirtieth (log L(sub x) less than or approx. equals 29.3 ergs/s) in the former Chandra observation in October 2000, which suggests that the X-ray activity, probably generated by magnetic activity, is triggered by an intermittent mass accretion episode such as FU Ori type outbursts. Because the source was detected at high significance in the XMM-Newton observations (approx. 2,000 cnts), X-ray properties of such young protostars can be well investigated for the first time. The light curves were constant in the 1st observation and increased linearly by a factor of two during 30 ksec in the 2nd observation. Both spectra showed iron K lines originated in hot thin-thermal plasma and fluorescence by cold gas. They can be reproduced by an absorbed thin-thermal plasma model with a Gaussian component at 6.4 keV (kT approx. 3-4 keV, L(sub x) approx. 7-20 x 10(exp 30) ergs/s). The rising timescale of the light curves in the 2nd observation was too slow for magnetically generated X-ray flares, whereas large equivalent width of the fluorescence iron K line in the 1st observation (approx. 810 eV) requires strong partial covering of the X-ray source. These results suggest that a confined hot (perhaps accretion) spot on the protostellar core was behind the star in the 1st observation and just appeared in the 2nd observation due to the core rotation with period of greater than or approx. 22.8 days, which is much slower than the break-up velocity previously assumed for young protostars. This means that the source had quiescent X-ray activity during the observations with an order of magnitude stronger level than Class I (older) protostars. We also consider whether the X-ray source associated with 10E could be shock heated plasma by a collision of a jet emanating from the tentative Class 0 object

First detection of Na I D lines in high-redshift damped Lya Systems

An NIR (1.18-1.35 mum) high-resolution spectrum of the gravitationally lensed QSO APM 08279+5255 was obtained with the Subaru Telescope IRCS using the AO system. We have detected strong Na I D lambdalambda5891, 5897 doublet absorption in high-redshift DLAs at zabs=1.062 and 1.181, confirming the presence of Na I, which was first reported for the rest-frame UV Na I lambdalambda3303.3, 3303.9 doublet by Petitjean et al. This is the first detection of Na I D absorption in a high-redshift (z>1) DLA. We have also detected a new Na I component in the zabs=1.062 DLA and four new components in the zabs=1.181 DLA. Using an empirical relationship between Na I and H I column density, we found that all components have large H I column density (logNHI [cm-2]>~20.3), so each component is classified as DLA absorption. We also detected strong Na I D absorption associated with a Mg II system at zabs=1.173. Because no other metal absorption lines were detected in this system at the velocity of the Na I absorption in previously reported optical spectra, we infer that this Na I absorption cloud probably appeared in the line of sight toward the QSO after the optical observation. This newly found cloud is likely to be a DLA based on its large estimated H I column density. We found that the NNaI/NCaII ratios in these DLAs are systematically smaller than those observed in the Galaxy; they are more consistent with the ratios seen in the LMC. This is consistent with dust depletion generally being smaller in lower metallicity environments. However, all five clouds of the zabs=1.181 system have a high NNaI/NCaII ratio, which is characteristic of cold dense gas. We tentatively suggest that the host galaxy of this system may be the most significant contributor to the gravitational lens toward APM 08279+5255. Based on data collected at the Subaru Telescope, which is operated by the National Astronomical Observatory of Japan

Carbon isotope ratio in 12CO/13CO toward local molecular clouds with near-infrared high-resolution spectroscopy of vibrational transition bands

We report the carbon monoxide isotope ratio in local molecular clouds toward LkH**alpha; 101, AFGL 490, and Mon R2 IRS 3. The vibrational transition bands of 12CO **nu;=2**lt;--0 and 13CO **nu;=1**lt;--0 were observed with high-resolution near-infrared spectroscopy (R=23,000) to measure the 12CO/13CO ratio. The isotopic ratios are 12CO/13CO=137+/-9 (LkH**alpha; 101), 86+/-49 (AFGL 490), and 158 (Mon R2 IRS 3), which are 1.5-2.8 times higher than the local interstellar medium value of 12CO/13CO=57+/-5 from millimeter C18O emission observations. This is not easily explained by saturation of the 13CO absorption. It is also questionable whether the selective photodestruction of 13CO can account for the difference between the Galactic trend and the present observation, because the molecular clouds are with high visible extinction (AV=10-70 mag), well shielded from destructive FUV radiation. The molecular gas associated with AFGL 490 and Mon R2 IRS 3 consists of multiple temperature components lying in the lines of sight. In the cool component (Tex**lt;100 K), the excitation temperature of 12CO is twice that of 13CO. We attribute the temperature discrepancy to the photon-trapping effect, which makes the radiative cooling of the main isotopomer less effective. Based on data collected at Subaru Telescope, which is operated by the National Astronomical Observatory of Japan