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Title: The disappearing envelope around the transitional class I object L43

Abstract

We present Submillimeter Array interferometric observations of the {sup 12}CO (J = 2-1), {sup 13}CO (J = 2-1), and C{sup 18}O (J = 2-1) lines and 225 GHz continuum emission and Submillimeter Telescope single-dish observations of C{sup 18}O (J = 2-1) toward L43, a protostellar object in transition from Class I to II. The 225 GHz continuum emission shows a weak (∼23.6 mJy), compact (<1000 AU) component associated with the central protostar. Our simulated observations show that it can be explained by dust thermal emission arising from an envelope which has a hole or a constant intensity region within a few hundred AU of the protostar. This suggests the disappearance or a lower concentration distribution of the envelope on a small scale. The {sup 12}CO and {sup 13}CO emission exhibit molecular outflows to the south and north. The C{sup 18}O emission shows two molecular blobs, which correspond to the reflection nebulosity seen in near-infrared images, while there is no C{sup 18}O emission associated with the protostar. The near-infrared features are likely due to the scattering at the positions of the blobs. The visible scattering features should result from the optical thinness of the envelope material, which is consistent with themore » less-concentrated distribution in the continuum emission. From single-dish observations, we found that the mass of the envelope (∼1.5 M{sub ☉}) + protostar (∼0.5 M{sub ☉}) is comparable with the virial mass of M{sub vir} = 1.0 M{sub ☉} within 40''. This suggests that the envelope is likely gravitationally bound. We suggest that the protostellar envelope of L43 has been disappearing by consumption through accretion, at least in the close vicinity of the protostar.« less

Authors:
 [1];  [2];  [3];  [4];  [5]
  1. Department of Astronomy, Graduate School of Science, The University of Tokyo, Hongo 7-3-1, Bunkyo-ku, Tokyo 113-0033 (Japan)
  2. Academia Sinica Institute of Astronomy and Astrophysics, P.O. Box 23-141, Taipei 10617, Taiwan (China)
  3. National Astronomical Observatory of Japan, Osawa 2-21-1, Mitaka-shi, Tokyo 181-8588 (Japan)
  4. Graduate University for Advanced Studies, Shonan International Village, Hayama-cho, Miura-gun, Kanagawa 240-0193 (Japan)
  5. Subaru Telescope, National Astronomical Observatory of Japan, 650 North A'ohoku Place, Hilo, HI 96720 (United States)
Publication Date:
OSTI Identifier:
22365735
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 789; Journal Issue: 2; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ABUNDANCE; CARBON 12; CARBON 13; CARBON MONOXIDE; DISTRIBUTION; EMISSION; MASS; OXYGEN 18; PROTOSTARS; REFLECTION; SCATTERING; SIMULATION; STARS; TELESCOPES

Citation Formats

Koyamatsu, Shin, Takakuwa, Shigehisa, Hayashi, Masahiko, Mayama, Satoshi, and Ohashi, Nagayoshi, E-mail: shin.koyamatsu@nao.ac.jp. The disappearing envelope around the transitional class I object L43. United States: N. p., 2014. Web. doi:10.1088/0004-637X/789/2/95.
Koyamatsu, Shin, Takakuwa, Shigehisa, Hayashi, Masahiko, Mayama, Satoshi, & Ohashi, Nagayoshi, E-mail: shin.koyamatsu@nao.ac.jp. The disappearing envelope around the transitional class I object L43. United States. doi:10.1088/0004-637X/789/2/95.
Koyamatsu, Shin, Takakuwa, Shigehisa, Hayashi, Masahiko, Mayama, Satoshi, and Ohashi, Nagayoshi, E-mail: shin.koyamatsu@nao.ac.jp. Thu . "The disappearing envelope around the transitional class I object L43". United States. doi:10.1088/0004-637X/789/2/95.
@article{osti_22365735,
title = {The disappearing envelope around the transitional class I object L43},
author = {Koyamatsu, Shin and Takakuwa, Shigehisa and Hayashi, Masahiko and Mayama, Satoshi and Ohashi, Nagayoshi, E-mail: shin.koyamatsu@nao.ac.jp},
abstractNote = {We present Submillimeter Array interferometric observations of the {sup 12}CO (J = 2-1), {sup 13}CO (J = 2-1), and C{sup 18}O (J = 2-1) lines and 225 GHz continuum emission and Submillimeter Telescope single-dish observations of C{sup 18}O (J = 2-1) toward L43, a protostellar object in transition from Class I to II. The 225 GHz continuum emission shows a weak (∼23.6 mJy), compact (<1000 AU) component associated with the central protostar. Our simulated observations show that it can be explained by dust thermal emission arising from an envelope which has a hole or a constant intensity region within a few hundred AU of the protostar. This suggests the disappearance or a lower concentration distribution of the envelope on a small scale. The {sup 12}CO and {sup 13}CO emission exhibit molecular outflows to the south and north. The C{sup 18}O emission shows two molecular blobs, which correspond to the reflection nebulosity seen in near-infrared images, while there is no C{sup 18}O emission associated with the protostar. The near-infrared features are likely due to the scattering at the positions of the blobs. The visible scattering features should result from the optical thinness of the envelope material, which is consistent with the less-concentrated distribution in the continuum emission. From single-dish observations, we found that the mass of the envelope (∼1.5 M{sub ☉}) + protostar (∼0.5 M{sub ☉}) is comparable with the virial mass of M{sub vir} = 1.0 M{sub ☉} within 40''. This suggests that the envelope is likely gravitationally bound. We suggest that the protostellar envelope of L43 has been disappearing by consumption through accretion, at least in the close vicinity of the protostar.},
doi = {10.1088/0004-637X/789/2/95},
journal = {Astrophysical Journal},
number = 2,
volume = 789,
place = {United States},
year = {Thu Jul 10 00:00:00 EDT 2014},
month = {Thu Jul 10 00:00:00 EDT 2014}
}
  • Subarcsecond images of the rotational line emission of CS and SO have been obtained toward the Class I protostar IRAS 04365+2535 in TMC-1A with ALMA. A compact component around the protostar is clearly detected in the CS and SO emission. The velocity structure of the compact component of CS reveals infalling–rotating motion conserving the angular momentum. It is well explained by a ballistic model of an infalling–rotating envelope with the radius of the centrifugal barrier (one-half of the centrifugal radius) of 50 au, although the distribution of the infalling gas is asymmetric around the protostar. The distribution of SO ismore » mostly concentrated around the radius of the centrifugal barrier of the simple model. Thus, a drastic change in chemical composition of the gas infalling onto the protostar is found to occur at a 50 au scale probably due to accretion shocks, demonstrating that the infalling material is significantly processed before being delivered into the disk.« less
  • We present dual-wavelength observations and modeling of the nearly edge-on Class 0 young stellar object L1157-mm. Using the Combined Array for Research in Millimeter-wave Astronomy, a nearly spherical structure is seen from the circumstellar envelope at the size scale of 10{sup 2}-10{sup 3} AU in both 1 mm and 3 mm dust emission. Radiative transfer modeling is performed to compare data with theoretical envelope models, including a power-law envelope model and the Terebey-Shu-Cassen model. Bayesian inference is applied for parameter estimation and information criterion is used for model selection. The results prefer the power-law envelope model against the Terebey-Shu-Cassen model.more » In particular, for the power-law envelope model, a steep density profile with an index of {approx}2 is inferred. Moreover, the dust opacity spectral index {beta} is estimated to be {approx}0.9, implying that grain growth has started at L1157-mm. Also, the unresolved disk component is constrained to be {approx}<40 AU in radius and {approx}<4-25 M{sub Jup} in mass. However, the estimate of the embedded disk component relies on the assumed envelope model.« less
  • We present an analysis of the H I and CO gas in conjunction with the Planck/IRAS submillimeter/far-infrared dust properties toward the most outstanding high latitude clouds MBM 53, 54, 55 and HLCG 92 – 35 at b = –30° to – 45°. The CO emission, dust opacity at 353 GHz (τ{sub 353}), and dust temperature (T {sub d}) show generally good spatial correspondence. On the other hand, the correspondence between the H I emission and the dust properties is less clear than in CO. The integrated H I intensity W{sub H} {sub I} and τ{sub 353} show a large scattermore » with a correlation coefficient of ∼0.6 for a T {sub d} range from 16 K to 22 K. We find, however, that W{sub H} {sub I} and τ{sub 353} show better correlation for smaller ranges of T {sub d} every 0.5 K, generally with a correlation coefficient of 0.7-0.9. We set up a hypothesis that the H I gas associated with the highest T {sub d} ≥ 21.5 K is optically thin, whereas the H I emission is generally optically thick for T {sub d} lower than 21.5 K. We have determined a relationship for the optically thin H I gas between atomic hydrogen column density and τ{sub 353}, N{sub H} {sub I} (cm{sup −2})=(1.5×10{sup 26})⋅τ{sub 353}, under the assumption that the dust properties are uniform and we have applied this to estimate N{sub H} {sub I} from τ{sub 353} for the whole cloud. N{sub H} {sub I} was then used to solve for T {sub s} and τ{sub H} {sub I} over the region. The result shows that the H I is dominated by optically thick gas having a low spin temperature of 20-40 K and a density of 40-160 cm{sup –3}. The H I envelope has a total mass of ∼1.2 × 10{sup 4} M {sub ☉}, an order of magnitude larger than that of the CO clouds. The H I envelope properties derived by this method do not rule out a mixture of H I and H{sub 2} in the dark gas, but we present indirect evidence that most of the gas mass is in the atomic state.« less
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