Abstract
We present the results on the physical properties of filaments and dense cores in IC 5146, as a part of the TRAO FUNS project. We carried out on-the-fly mapping observations using the Taeduk ...Radio Astronomy Observatory (TRAO) 14 m telescope covering about 1 square degree of the area of IC 5146 using various molecular lines. We identified 14 filaments (24 in total, including sub-filaments) from the C
18
O (1–0) data cube and 22 dense cores from the N
2
H
+
(1–0) data. We examined the filaments’ gravitational criticality, turbulence properties, accretion rate from filaments to dense cores, and relative evolutionary stages of cores. Most filaments in IC 5146 are gravitationally supercritical within the uncertainty, and most dense cores are formed in them. We found that dense cores in the hubs show a systemic velocity shift of ∼0.3 km s
−1
between the N
2
H
+
and C
18
O gas. Besides, these cores are subsonic or transonic, while the surrounding filament gas is transonic or supersonic, indicating that the cores in the hubs are likely formed by the dissipation of turbulence in the colliding turbulent filaments and the merging is still ongoing. We estimated a mass accretion rate of 15–35
M
⊙
Myr
−1
from the filaments to the dense cores, and the required timescales to collect the current core mass are consistent with the lifetime of the dense cores. The structures of filaments and dense cores in the hub can form from a collision of turbulent converging flows, and mass flow along the filaments to the dense cores may play an important role in forming dense cores.
CS Depletion in Prestellar Cores Kim, Shinyoung; Lee, Chang Won; Gopinathan, Maheswar ...
The Astrophysical journal,
03/2020, Volume:
891, Issue:
2
Journal Article
Peer reviewed
Open access
The CS molecule is known to be adsorbed onto dust in cold and dense conditions, causing it to be significantly depleted in the central region of cores. This study is aimed to investigate the ...depletion of the CS molecule using the optically thin molecular line observations. We mapped five prestellar cores, L1544, L1552, L1689B, L694-2, and L1197, using two molecular lines, (J = 2 − 1) and (J = 1 − 0) with the NRO 45 m telescope, doubling the number of cores where the CS depletion was probed using . In most of our targets, the distribution of emission shows features that suggest that the CS molecule is generally depleted in the center of the prestellar cores. The radial profile of the CS abundance with respect to directly measured from the CS emission and the Herschel dust emission indicates that the CS molecule is depleted by a factor of ∼3 toward the central regions of the cores with respect to their outer regions. The degree of the depletion is found to be even more enhanced, by an order of magnitude, when the contaminating effect introduced by the presence of CS molecules in the surrounding envelope that lie along the line of sight is removed. Except for L1197-which is classified as relatively the least evolved core in our targets, based on its observed physical parameters-we found that the remaining four prestellar cores are suffering from significant CS depletion at their central region, regardless of the relative difference in their evolutionary status.
This paper presents our observational attempts to precisely measure the central mass of a proto-brown dwarf candidate, L328-IRS, in order to investigate whether L328-IRS is in the substellar mass ...regime. Observations were made for the central region of L328-IRS with the dust continuum and CO isotopologue line emission at Atacama Large Millimeter/submillimeter Array (ALMA) band 6, discovering the detailed outflow activities and a deconvolved disk structure of a size of ∼87 × 37 au. We investigated the rotational velocities as a function of the disk radius, finding that its motions between 130 and 60 au are partially fitted with a Keplerian orbit by a stellar object of ∼0.30 M , while the motions within 60 au do not follow any Keplerian orbit at all. This makes it difficult to lead a reliable estimation of the mass of L328-IRS. Nonetheless, our ALMA observations were useful enough to well constrain the inclination angle of the outflow cavity of L328-IRS as ∼66°, enabling us to better determine the mass accretion rate of ∼8.9 × 10−7 M yr−1. From assumptions that the internal luminosity of L328-IRS is mostly due to this mass accretion process in the disk, or that L328-IRS has mostly accumulated the mass through this constant accretion rate during its outflow activity, its mass was estimated to be ∼0.012-0.023 M , suggesting L328-IRS to be a substellar object. However, we leave our identification of L328-IRS as a proto-brown dwarf to be tentative because of various uncertainties, especially regarding the mass accretion rate.
Abstract
Ten protostellar outflows in the Orion molecular clouds were mapped in the
12
CO/
13
CO
J
= 6 → 5 and
12
CO
J
= 7 → 6 lines. The maps of these mid-
J
CO lines have an angular resolution of ...about 10″ and a typical field size of about 100″. The physical parameters of the molecular outflows were derived, including mass transfer rates, kinetic luminosities, and outflow forces. The outflow sample was expanded by reanalyzing archival data of nearby low-luminosity protostars to cover a wide range of bolometric luminosities. Outflow parameters derived from other transitions of CO were compared. The mid-
J
(
J
up
≈ 6) and low-
J
(
J
up
≤ 3) CO line wings trace essentially the same outflow component. By contrast, the high-
J
(up to
J
up
≈ 50) line-emission luminosity of CO shows little correlation with the kinetic luminosity from the
J
= 6 → 5 line, which suggests that they trace distinct components. The low-/mid-
J
CO line wings trace long-term outflow behaviors, while the high-
J
CO lines are sensitive to short-term activities. The correlations between the outflow parameters and protostellar properties are presented, which shows that the strengths of molecular outflows increase with bolometric luminosity and envelope mass.
Abstract
We present the results of a single-dish survey toward 95 very low luminosity objects (VeLLOs) in optically thick (HCN 1−0) and thin (N
2
H
+
1−0) lines performed for the purpose of ...understanding the physical processes of inward motions in the envelopes of the VeLLOs and characterizing their true nature. The normalized velocity differences (
δ
V
HCN
) between the peak velocities of the two lines were derived for 41 VeLLOs detected in both lines. The
δ
V
distribution of these VeLLOs is found to be significantly skewed to the blue, indicating the dominance of infalling motions in their envelopes. The infall speeds were derived for 15 infall candidates by using the HILL5 radiative transfer model. The speeds were in the range of 0.03−0.3 km s
−1
, with a median value of 0.16 km s
−1
, consistent with the gravitational freefall speeds from pressure-free envelopes. The mass infall rates calculated from the infall speeds are mostly of the order of 10
−6
M
⊙
yr
−1
, with a median value of (3.4 ± 1.5) × 10
−6
M
⊙
yr
−1
. These are found to be also consistent with the values predicted with the inside-out collapse model and show a fairly good correlation with the internal luminosities of the VeLLOs. This again indicates that the infall motions observed toward the VeLLOs are likely to be due to the gravitational infall motions in their envelopes. Our study suggests that most of the VeLLOs are potentially faint protostars, while two of the VeLLOs could possibly be proto−brown dwarf candidates.
Abstract The James Clerk Maxwell Telescope (JCMT) Transient Survey has been monitoring eight Gould Belt low-mass star-forming regions since 2015 December and six somewhat more distant ...intermediate-mass star-forming regions since 2020 February with the Submillimeter Common User Bolometer Array 2 on board JCMT at 450 and 850 μ m and with an approximately monthly cadence. We introduce our pipeline v2 relative calibration procedures for image alignment and flux calibration across epochs, improving on our previous pipeline v1 by decreasing measurement uncertainties and providing additional robustness. These new techniques work at both 850 and 450 μ m, where version 1 only allowed investigation of the 850 μ m data. Pipeline v2 achieves better than 0.″5 relative image alignment, less than a tenth of the submillimeter beam widths. The version 2 relative flux calibration is found to be 1% at 850 μ m and <5% at 450 μ m. The improvement in the calibration is demonstrated by comparing the two pipelines over the first 4 yr of the survey and recovering additional robust variables with version 2. Using the full 6 yr of the Gould Belt survey, the number of robust variables increases by 50%, and at 450 μ m we identify four robust variables, all of which are also robust at 850 μ m. The multiwavelength light curves for these sources are investigated and found to be consistent with the variability being due to dust heating within the envelope in response to accretion luminosity changes from the central source.
We present the results of a systematic search for molecular outflows in 68 Very Low Luminosity Objects (VeLLOs) from single-dish observations in CO isotopologues, finding 16 VeLLOs that show clear ...outflow signatures in the CO maps. Together with an additional three VeLLOs from the literature, we analyzed the outflow properties for these 19 VeLLOs, identifying 15 VeLLOs as proto-brown-dwarf (proto-BD) candidates and 4 VeLLOs as likely faint protostar candidates. The proto-BD candidates are found to have a mass accretion rate (∼10−8-10−7 M yr−1) lower than that of the protostar candidates ( 10−6 M yr−1). Their accretion luminosities are similar to or smaller than their internal luminosities, implying that many proto-BD candidates might have had either small accretion activity in a quiescent manner throughout their lifetimes, or be currently exhibiting relatively higher (or episodic) mass accretion than in the past. Outflows of many proto-BDs show strong trends of being less active if they are fainter or have less massive envelopes. The outflow forces and internal luminosities for more than half of the proto-BD candidates seem to follow the evolutionary track of a protostar with an initial envelope mass of ∼0.08 M , indicating that some BDs may form in less massive dense cores in a similar way to normal stars. But, because there also exists a significant fraction (about 40%) of proto-BDs with a much weaker outflow force than expected from the relations for protostars, we should not rule out the possibility of other formation mechanism for BDs.
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•ANO9/TMEM16J is activated by cAMP/PKA signal.•Unlike Anoctamin 1 or 2, a Ca2+-activated Clchannel family, ANO9 is a cation channel.•Colon cells expressed high levels of Ano9 and ...showed cAMP-dependent currents.
Anoctamins (ANOs) are multifunctional membrane proteins that consist of 10 homologs. ANO1 (TMEM16A) and ANO2 (TMEM16B) are anion channels activated by intracellular calcium that meditate numerous physiological functions. ANO6 is a scramblase that redistributes phospholipids across the cell membrane. The other homologs are not well characterized. We found ANO9/TMEM16J is a cation channel activated by a cAMP-dependent protein kinase A (PKA). Intracellular cAMP-activated robust currents in whole cells expressing ANO9, which were inhibited by a PKA blocker. A cholera toxin that persistently stimulated adenylate cyclase activated ANO9 as did the application of PKA. The cAMP-induced ANO9 currents were permeable to cations. The cAMP-dependent ANO9 currents were augmented by intracellular Ca2+. Ano9 transcripts were predominant in the intestines. Human intestinal SW480 cells expressed high levels of Ano9 transcripts and showed PKA inhibitor-reversible cAMP-dependent currents. We conclude that ANO9 is a cation channel activated by a cAMP/PKA pathway and could play a role in intestine function.
ABSTRACT We present the results of a search for Very Low-Luminosity Objects (VeLLOs) in the Gould Belt (GB) clouds using infrared and sub-millimeter (sub-mm) data from 1.25 to 850 m and our (J = 1−0) ...observations. We modified the criteria by Dunham et al. to select the VeLLOs in the GB clouds, finding 95 VeLLO candidates, 79 of which are newly identified in this study. Out of 95 sources, 44 were detected in both sub-mm continuum and emission and were classified as Group A (the VeLLOs), and 51 sources detected in either sub-mm emission or emission were classified with Group B as candidate VeLLOs. We find that these VeLLOs and the candidates are forming in environments different from those of the likely VeLLOs. Seventy-eight sources are embedded within their molecular clouds, and thus are likely VeLLOs forming in a dense environment. The remaining 17 sources are located in low-level extinction regions ( ) connected to the clouds, and can be either background sources or candidate substellar objects forming in an isolated mode. The VeLLOs and the candidates are likely more luminous and their envelopes tend to be more massive in denser environments. The VeLLOs and the candidates are more populous in the clouds where more YSOs form, indicating that they form in a manner similar to that of normal YSOs. The bolometric luminosities and temperatures of the VeLLOs are compared to predictions of episodic accretion models, showing that the low luminosities for most VeLLOs can be well explained by their status in the quiescent phases of a cycle of episodic mass accretion.
A critical unmet clinical need to combat the global tuberculosis epidemic is the development of potent agents capable of reducing the time of multi-drug-resistant (MDR) and extensively-drug-resistant ...(XDR) tuberculosis therapy. In this paper, we report on the optimization of imidazo1,2-apyridine amide (IPA) lead compound 1, which led to the design and synthesis of Q203 (50). We found that the amide linker with IPA core is very important for activity against Mycobacterium tuberculosis H37Rv. Linearity and lipophilicity of the amine part in the IPA series play a critical role in improving in vitro and in vivo efficacy and pharmacokinetic profile. The optimized IPAs 49 and 50 showed not only excellent oral bioavailability (80.2% and 90.7%, respectively) with high exposure of the area under curve (AUC) but also displayed significant colony-forming unit (CFU) reduction (1.52 and 3.13 log10 reduction at 10 mg/kg dosing level, respectively) in mouse lung.
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