- ID:
- ivo://CDS.VizieR/J/A+A/651/A120
- Title:
- CH_3_OCHD_2_ experimental frequencies
- Short Name:
- J/A+A/651/A120
- Date:
- 22 Feb 2022
- Publisher:
- CDS
- Description:
- In 2013, we have published the first rotational analysis and detection of mono-deuterated dimethyl ether in the solar-type protostar IRAS 16293-2422 with the IRAM 30m telescope. Dimethyl ether is one of the most abundant complex organic molecules (COMs) in star-forming regions and their D-to-H (D/H) ratios is important to understand its chemistry and trace the source history. We present the first analysis of doubly-deuterated dimethyl ether (methoxy-d2-methane, 1,1-dideuteromethylether) in its ground- vibrational state, based on an effective Hamiltonian for an asymmetric rotor molecules with internal rotors. The analysis covers the frequency range 0.15-1.5THz. The laboratory rotational spectrum of this species was measured between 150 and 1500GHz with the Lille's submillimeter spectrometer. For the astronomical detection, we used the Atacama Large Millimeter/submillimeter Array (ALMA) observations from the Protostellar Interferometric Line Survey, PILS. New sets of spectroscopic parameters have been determined by a least squares fit with the ERHAM code for both symmetric and asymmetric conformers. As for the mono-deuterated species, these parameters have permitted the first identification in space of both conformers of a doubly-deuterated dimethyl ether via detection near the B component of the Class 0 protostar IRAS 16293-2422.
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Search Results
- ID:
- ivo://CDS.VizieR/J/ApJ/851/L46
- Title:
- CH_3_OCH_2_OH ALMA detection in NGC 6334I
- Short Name:
- J/ApJ/851/L46
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report the detection of interstellar methoxymethanol (CH_3_OCH_2_OH) in Atacama Large Millimeter/submillimeter Array (ALMA) Bands 6 and 7 toward the MM1 core in the high-mass star-forming region NGC 6334I at ~0.1-1" spatial resolution. A column density of 4(2)x10^18^cm^-2^ at T_ex_=200K is derived toward MM1, ~34 times less abundant than methanol (CH_3_OH), and significantly higher than predicted by astrochemical models. Probable formation and destruction pathways are discussed, primarily through the reaction of the CH_3_OH photodissociation products, the methoxy (CH_3_O) and hydroxymethyl (CH_2_OH) radicals. Finally, we comment on the implications of these mechanisms on gas-phase versus grain-surface routes operative in the region, and the possibility of electron-induced dissociation of CH3OH rather than photodissociation.
- ID:
- ivo://CDS.VizieR/J/ApJS/155/149
- Title:
- CH_3_OH 7_0_-6_1_ A^+^ maser sources
- Short Name:
- J/ApJS/155/149
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a Very Large Array survey of 44 massive star-forming regions in the 44GHz 7_0_-6_1_ A^+^ methanol transition; 37 fields showed maser emission. Thirty-one sources were also observed in the 23GHz 9_2_-10_1_ A^+^ methanol line; two fields showed maser emission.
- ID:
- ivo://CDS.VizieR/J/A+A/563/A68
- Title:
- CH_3_OH and H_2_O Galactic center masers
- Short Name:
- J/A+A/563/A68
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a study of star formation in the central molecular zone (CMZ) of our Galaxy through the association of three star formation indicators: 6.7GHz CH_3_OH masers, 22GHz H_2_O masers, and enhanced 4.5{mu}m emission ('green') sources. We explore how star formation in the CMZ (|l|<1.3{deg}, |b|<10') compares with that of the Galactic disk (6{deg}>l>345{deg}, |b|<2{deg}). Using an automated algorithm, we search for green sources toward 6.7GHz CH_3_OH masers detected in the Parkes Methanol Multibeam Survey. We combine these results with lists of 22GHz H_2_O masers, including our Mopra survey of the CMZ. We find that the correlation of CH_3_OH masers with green sources is a function of Galactic latitude, with a minimum close to b=0 and increasing with |b| (toward the central part of the Galaxy, 6{deg}>l>345{deg}, |b|<2{deg}). We find no significant difference between the correlation rate of CH_3_OH masers with green sources in the CMZ and the disk. This suggests that although the physical conditions of the gas are different in the CMZ from that of the Galactic disk, once gravitational instability sets in at sufficiently high densities, signatures of star formation appear to be similar in both regions. Moreover, the detection of green sources, even at the distance of the Galactic center, shows that our technique can easily identify the early stages of star formation, especially in low-extinction regions of the Galaxy. Through the association of H_2_O and CH_3_OH masers, we identify 15 star-forming sites in the CMZ. We find a higher correlation rate of coincident H_2_O and CH_3_OH masers within the CMZ compared to the Galactic disk, indicating a difference in the maser evolutionary sequence for star-forming cores in these two regions.
- ID:
- ivo://CDS.VizieR/J/other/NatAs/5.684
- Title:
- CH3OH in the HD100546 disk
- Short Name:
- J/other/NatAs/5.
- Date:
- 17 Jan 2022 00:30:51
- Publisher:
- CDS
- Description:
- Quantifying the composition of the material in protoplanetary disks is paramount to determining the potential for exoplanetary systems to produce and support habitable environments. When considering potential habitability, complex organic molecules are of relevance, key among which is methanol (CH_3_OH). Methanol primarily forms at low temperatures via the hydrogenation of CO ice on the surface of icy dust grains and is a necessary basis for the formation of more complex species such as amino acids and proteins. We report the detection of CH_3_OH in a disk around a young, luminous A-type star, HD 100546. This disk is warm and therefore does not host an abundant reservoir of CO ice. We argue that the CH_3_OH cannot form in situ, and hence this disk has probably inherited complex-organic-molecule-rich ice from an earlier cold dark cloud phase. This is strong evidence that at least some interstellar organic material survives the disk formation process and can then be incorporated into forming planets, moons and comets. Therefore, crucial pre-biotic chemical evolution already takes place in dark star-forming clouds.
- ID:
- ivo://CDS.VizieR/J/A+A/564/L2
- Title:
- CH3OH line parameters in comets ISON and Lovejoy
- Short Name:
- J/A+A/564/L2
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present molecular observations carried out with the IRAM 30m telescope at wavelengths around 1.15mm towards the Oort cloud comets C/2012 S1 (ISON) and C/2013 R1 (Lovejoy) when they were at 0.6 and 1AU, respectively, from the Sun. We detect HCN, HNC, and CH3OH in both comets, together with the ion HCO+ in comet ISON and a few weak unidentified lines in comet Lovejoy, one of which could be tentatively assigned to methylamine (CH3NH2). The monitoring of the HCN J=3-2 line showed a tenfold enhancement in comet ISON on November 14.4 UT due to an outburst of activity whose exact origin is unknown, although it could be related to some break up of the nucleus. The set of CH_3_OH lines observed was used to derive the kinetic temperature in the coma, 90K in comet ISON and 60K in comet Lovejoy. The HNC/HCN ratios derived, 0.18 in ISON and 0.05 in Lovejoy, are comparable to those found in most previous comets and are consistent with an enhancement of HNC as the comet approaches the Sun. Phosphine (PH3) was also searched for unsuccessfully in both comets through its fundamental 1_0_-0_0_ transition, and 3 sigma upper limits corresponding to PH_3_/H_2_O ratios 4-10 times above the solar P/O elemental ratio could be derived.
3657. CH_3_OH maser sources
- ID:
- ivo://CDS.VizieR/J/other/RAA/10.67
- Title:
- CH_3_OH maser sources
- Short Name:
- J/other/RAA/10.6
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Using the 13.7m telescope of the Purple Mountain Observatory (PMO), a survey of the J=1-0 lines of CO and its isotopes was carried out on 98 methanol maser sources in January 2008. Eighty-five sources have infrared counterparts within one arcmin.
- ID:
- ivo://CDS.VizieR/J/ApJ/702/1615
- Title:
- CH_3_OH maser survey of EGOs
- Short Name:
- J/ApJ/702/1615
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results of a high angular resolution Very Large Array (VLA) Class I 44GHz and Class II 6.7GHz CH_3_OH maser survey of a sample of ~20 massive young stellar object (MYSO) outflow candidates selected on the basis of extended 4.5um emission in Spitzer Galactic Legacy Infrared Mid-Plane Survey Extraordinaire images. These 4.5um selected candidates are referred to as extended green objects (EGOs), for the common coding of this band as green in three-color Infrared Array Camera images. The detection rate of 6.7GHz Class II CH_3_OH masers, which are associated exclusively with massive YSOs, toward EGOs is >~64% - nearly double the detection rate of surveys using other MYSO selection criteria. The detection rate of Class I 44GHz CH_3_OH masers, which trace molecular outflows, is ~89% toward EGOs associated with 6.7GHz CH_3_OH masers.
- ID:
- ivo://CDS.VizieR/J/ApJS/227/10
- Title:
- CH_3_OH & OH line emission from Galactic center
- Short Name:
- J/ApJS/227/10
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Class I methanol masers are collisionally pumped and are generally correlated with outflows in star-forming sites in the Galaxy. Using the Very Large Array in its A-array configuration, we present a spectral line survey to identify methanol J=4_-1_->3_0_E emission at 36.169GHz. Over 900 pointings were used to cover a region 66'x13' along the inner Galactic plane. A shallow survey of OH at 1612, 1665, 1667, and 1720MHz was also carried out over the area covered by our methanol survey. We provide a catalog of 2240 methanol masers with narrow line-widths of ~1km/s, spatial resolutions of ~0.14"x0.05", and rms noises ~20mJy/beam per channel. Lower limits on the brightness temperature range from 27000 to 10000000K, showing that the emission is of non-thermal origin. We also provide a list of 23 OH (1612), 14 OH (1665), 5 OH (1667), and 5 OH (1720MHz) masers. The origin of such a large number of methanol masers is not clear. Many methanol masers appear to be associated with infrared dark clouds, though it appears unlikely that the entire population of these masers traces the early phase of star formation in the Galactic center.
3660. Choirs, HI galaxy groups
- ID:
- ivo://CDS.VizieR/J/MNRAS/433/543
- Title:
- Choirs, HI galaxy groups
- Short Name:
- J/MNRAS/433/543
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- H{alpha} observations centred on galaxies selected from the Hi Parkes All-Sky Survey (HiPASS) typically show one and sometimes two star-forming galaxies within the ~15arcmin beam of the Parkes 64m HI detections. In our Survey for Ionization in Neutral Gas Galaxies (SINGG) we found 15 cases of HiPASS sources containing four or more emission line galaxies (ELGs). We name these fields Choir groups. In the most extreme case, we found a field with at least nine ELGs. In this paper, we present a catalogue of Choir group members in the context of the wider SINGG sample. The dwarf galaxies in the Choir groups would not be individually detectable in HiPASS at the observed distances if they were isolated, but are detected in SINGG narrow-band imaging due to their membership of groups with sufficiently large total HI mass. The ELGs in these groups are similar to the wider SINGG sample in terms of size, H{alpha} equivalent width and surface brightness. Eight of these groups have two large spiral galaxies with several dwarf galaxies and may be thought of as morphological analogues of the Local Group. However, on average our groups are not significantly Hi deficient, suggesting that they are at an early stage of assembly, and more like the M81 group. The Choir groups are very compact at typically only 190kpc in projected distance between the two brightest members. They are very similar to SINGG fields in terms of star formation efficiency (SFE; the ratio of star formation rate to HI mass), showing an increasing trend in SFE with stellar mass.
