- ID:
- ivo://CDS.VizieR/J/ApJ/761/34
- Title:
- Kinematical study of the optical ejecta of GK Per
- Short Name:
- J/ApJ/761/34
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a kinematical study of the optical ejecta of GK Per. It is based on proper-motion measurements of 282 knots from ~20 images spanning 25 years. Doppler shifts are also computed for 217 knots. The combination of proper motions and radial velocities allows a unique three-dimensional view of the ejecta to be obtained. The main results are as follows: (1) the outflow is a thick shell in which knots expand with a significant range of velocities, mostly between 600 and 1000 km/s, (2) kinematical ages indicate that knots have suffered only a modest deceleration since their ejection a century ago, (3) no evidence for anisotropy in the expansion rate is found, (4) velocity vectors are generally aligned along the radial direction, but a symmetric pattern of non-radial velocities is also observed at specific directions, and (5) the total H{alpha}+[N II] flux has been linearly decreasing at a rate of 2.6% per year in the past decade. The eastern nebular side is fading at a slower rate than the western side. Some of the knots were displayed a rapid change of brightness during the 2004-2011 period. Over a longer timescale, a progressive circularization and homogenization of the nebula are taking place; (6) a kinematic distance of 400+/-30 pc is determined. These results raise some problems with the previous interpretations of the evolution of GK Per. In particular, the idea of a strong interaction of the outflow with the surrounding medium in the southwest quadrant is not supported by our data.
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- ID:
- ivo://CDS.VizieR/J/A+A/579/A51
- Title:
- Kinematic and thermal structure of IRDCs
- Short Name:
- J/A+A/579/A51
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We studied the kinematic and thermal structure of the early phases of high- mass and intermediate mass star formation using ammonia observations from the Very Large Array (VLA) and the Effelsberg 100m telescope.
- ID:
- ivo://CDS.VizieR/J/ApJ/699/1153
- Title:
- Kinematic distances to GRS molecular clouds
- Short Name:
- J/ApJ/699/1153
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Kinematic distances to 750 molecular clouds identified in the ^13^COJ=1-0 Boston University-Five College Radio Astronomy Observatory Galactic Ring Survey (GRS) are derived assuming the Clemens rotation curve of the Galaxy. The kinematic distance ambiguity is resolved by examining the presence of HI self-absorption toward the ^13^CO emission peak of each cloud using the Very Large Array Galactic Plane Survey. We also identify 21cm continuum sources embedded in the GRS clouds in order to use absorption features in the HI 21cm continuum to distinguish between near and far kinematic distances. The Galactic distribution of GRS clouds is consistent with a four-arm model of the Milky Way. The locations of the Scutum-Crux and Perseus arms traced by GRS clouds match star-count data from the Galactic Legacy Infrared Mid-Plane Survey Extraordinaire star-count data. We conclude that molecular clouds must form in spiral arms and be short-lived (lifetimes <10^7^yr) in order to explain the absence of massive, ^13^CO bright molecular clouds in the interarm space.
- ID:
- ivo://CDS.VizieR/J/A+A/617/A27
- Title:
- Kinematics of dense gas in L1495 filament
- Short Name:
- J/A+A/617/A27
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Nitrogen bearing species, such as NH_3_, N_2_H^+^, and their deuterated isotopolo- gues show enhanced abundances in CO-depleted gas, and thus are perfect tracers of dense and cold gas in star-forming regions. The Taurus molecular cloud contains the long L1495 filament providing an excellent opportunity to study the process of star formation in filamentary environments. We study the kinematics of the dense gas of starless and protostellar cores traced by the N_2_D^+^(2-1), N_2_H^+^(1-0), DCO^+^(2-1), and H^13^CO^+^(1-0) transitions along the L1495 filament and the kinematic links between the cores and surrounding molecular cloud. We measured velocity dispersions, local and total velocity gradients, and estimate the specific angular momenta of 13 dense cores in the four transitions using on-the-fly observations with the IRAM 30-m antenna. To study a possible connection to the filament gas, we used the C^18^O(1-0) observations.
- ID:
- ivo://CDS.VizieR/J/AJ/162/224
- Title:
- King 7 Vilnius photometry. II. Extinctions
- Short Name:
- J/AJ/162/224
- Date:
- 15 Mar 2022
- Publisher:
- CDS
- Description:
- Interstellar extinction in two concentric square areas of the sizes 1.25x1.25deg^2^ and 0.2x0.2deg^2^ in the direction of open cluster King7 is investigated applying two-dimensional photometric classification of stars observed in the Vilnius seven-color photometric system down to V=15.5mag (1084 stars) and 19.5mag (584 stars), respectively. The cluster members (284 stars) are identified applying their coordinates, proper motions, and parallaxes taken from the Gaia EDR3 catalog. New parameters of the cluster (distance, diameter, interstellar extinction, and age) are obtained. Photogeometric distances of stars are taken from Bailer-Jones et al. (2021) based on the Gaia parallaxes from EDR3. Physically the cluster is located at the outer edge of the Perseus spiral arm at d=2.74kpc, its diameter is 9.6pc, the age is 175{+/-}25Myr, the earliest stars are of spectral classes B6-B7. The average interstellar extinction A_V_=4.24mag. From the radial velocities of CO and the Galactic rotation curve we estimate distances to the nearby dust clouds TGU H989 P2 and P3 at 650-670pc from the Sun.
- ID:
- ivo://CDS.VizieR/J/ApJ/866/139
- Title:
- Knots in the deep [FeII]+[SiI] image of the SNR Cas A
- Short Name:
- J/ApJ/866/139
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a long-exposure (~10hr), narrowband image of the supernova (SN) remnant Cassiopeia A (Cas A) centered at 1.644{mu}m emission. The passband contains [FeII] 1.644{mu}m and [SiI] 1.645{mu}m lines, and our "deep [FeII]+[SiI] image" provides an unprecedented panoramic view of Cas A, showing both shocked and unshocked SN ejecta, together with shocked circumstellar medium at subarcsecond (~0.7" or 0.012pc) resolution. The diffuse emission from the unshocked SN ejecta has a form of clumps, filaments, and arcs, and their spatial distribution correlates well with that of the Spitzer [SiII] infrared emission, suggesting that the emission is likely due to [SiI] not [FeII] as in shocked material. The structure of the optically invisible western area of Cas A is clearly seen for the first time. The area is filled with many quasi-stationary flocculi (QSFs) and fragments of the disrupted ejecta shell. We identified 309 knots in the deep [FeII]+[SiI] image and classified them into QSFs and fast-moving knots (FMKs). The comparison with previous optical plates indicates that the lifetime of most QSFs is >~60yr. The total H+He mass of QSFs is ~0.23M_{sun}_, implying that the mass fraction of dense clumps in the progenitor's mass ejection immediately prior to the SN explosion is about 4%-6%. FMKs in the deep [FeII]+[SiI] image mostly correspond to S-rich ejecta knots in optical studies, while those outside the southeastern disrupted ejecta shell appear Fe-rich. The mass of the [FeII] line emitting, shocked dense Fe ejecta is ~3x10^-5^M_{sun}_.
- ID:
- ivo://CDS.VizieR/J/A+A/609/A121
- Title:
- Lab measurements for C-cyanomethanimine
- Short Name:
- J/A+A/609/A121
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- C-cyanomethanimine (HNCHCN), existing in the two Z and E isomeric forms, is a key prebiotic molecule, but, so far, only the E isomer has been detected towards the massive star forming region Sagittarius B2(N) using transitions in the radio wavelength domain. With the aim of detecting HNCHCN in Sun-like star-forming regions, the laboratory investigation of its rotational spectrum has been extended to the milllimeter-/submillimeter-wave (mm-/submm-) spectral window where several unbiased spectral surveys have been already obtained. High-resolution laboratory measurements of the rotational spectrum of C-cyanomethanimine were carried out in the 100-420GHz range using a frequency-modulation absorption spectrometer. The C-cyanomethanimine spectral features were then searched for in the mm-wave range using the high-sensitivity and unbiased spectral surveys obtained with the IRAM 30-m antenna in the ASAI context, the earliest stages of star formation from starless to evolved Class I objects being sampled. For both the Z and E isomers, the spectroscopic work has led to an improved and extended knowledge of the spectroscopic parameters, thus providing accurate predictions of the rotational signatures up to ~700GHz. So far, no C-cyanomethanimine emission has been detected towards the ASAI targets, and upper limits on the column density of 10^11^-10^12^cm^-2^ could only be derived. Consequently, the C-cyanomethanimine abundances have to be less than a few 10^-10^ for starless and hot-corinos. A less stringent constraint, <=10^-9^, is obtained for shocks sites. The combination of the upper limits on the abundances of C-cyanomethanimine together with accurate laboratory frequencies up to ~700GHz poses the basis for future higher sensitivity searches around Sun-like star forming regions. For compact (typically less than 1 arcsec) and chemically enriched sources such as hot-corinos, the use of interferometers as NOEMA and ALMA in their extended configurations are clearly needed.
- ID:
- ivo://CDS.VizieR/J/A+A/619/A92
- Title:
- Laboratory analysis of methylketene
- Short Name:
- J/A+A/619/A92
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The analysis of isomeric species of a compound observed in the interstellar medium is a useful tool to understand the chemistry of complex organic molecules. It could, likewise, assist to detect new species. Our goal consists on analyzing one of the two most stable species of the C_3_H_4_O family, methyl ketene, whose actual rotational parameters are not precise enough to allow its detection in the ISM. The obtained parameters will be used to search for it in the high-mass star-forming regions Orion KL and Sagittarius B2 as well as in the cold dark clouds TMC-1 in Taurus Molecular Cloud and Barnard 1 (B1-b).
- ID:
- ivo://CDS.VizieR/J/A+A/647/A179
- Title:
- Laboratory spectroscopy of isotopic c-H2C3O
- Short Name:
- J/A+A/647/A179
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Cyclopropenone was first detected in the cold and less dense envelope of the giant molecular cloud Sagittarius B2(N). It was found later in several cold dark clouds and it may be possible to detect its minor isotopic species in these environments. In addition, the main species may well be identified in warmer environments. We aim to extend existing line lists of isotopologs of c-H_2_C_3_O from the microwave to the millimeter region and create one for the singly deuterated isotopolog to facilitate their detections in space. Furthermore, we aim to extend the line list of the main isotopic species to the submillimeter region and to evaluate an equilibrium structure of the molecule.
- ID:
- ivo://CDS.VizieR/J/PAZh/33/143
- Title:
- Laboratory studies of HNCO
- Short Name:
- J/PAZh/33/143
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Detailed studies of the internal motions of dark clouds using spectral lines of many molecules require a laboratory frequency accuracy of the order of a few m/s. Based on our laboratory studies of the HNCO rotational spectrum in the ground vibration state, we have increased significantly the accuracy of frequency calculations in a wide range of quantum numbers. We have achieved an 1{sigma} uncertainty for rotational transitions in the Ka=0,1 states recalculated to the Doppler velocity scale <2m/s for all frequencies <1.1THz. This value allows radio-astronomical measurements with an accuracy comparable to that of the highest-precision observations based on spectral lines of other molecules.
