scholarly journals η Carinae: high angular resolution continuum, H30α and He30α ALMA images

2020 ◽  
Vol 499 (2) ◽  
pp. 2493-2512
Author(s):  
Zulema Abraham ◽  
Pedro P B Beaklini ◽  
Pierre Cox ◽  
Diego Falceta-Gonçalves ◽  
Lars-Åke Nyman
Keyword(s):  
Angular Resolution ◽  
Line Emission ◽  
High Angular Resolution ◽  
Proper Motions ◽  
Recombination Line ◽  
Compact Source ◽  
Continuum Source ◽  
Velocity Images ◽  
First Time ◽  
Compact Sources

ABSTRACT We present images of η Carinae in the recombination lines H30α and He30α and the underlying continuum with 50 mas resolution (110 au), obtained with ALMA. For the first time, the 230 GHz continuum image is resolved into a compact core, coincident with the binary system position, and a weaker extended structure to the NW of the compact source. Iso-velocity images of the H30α recombination line show at least 16 unresolved sources with velocities between −30 and −65 km s−1 distributed within the continuum source. A NLTE model, with density and temperature of the order of 107 cm−3 and 104 K, reproduce both the observed H30α line profiles and their underlying continuum flux densities. Three of these sources are identified with Weigelt blobs D, C, and B; estimating their proper motions, we derive ejection times (in years) of 1952.6, 1957.1, and 1967.6, respectively, all of which are close to periastron passage. Weaker H30α line emission is detected at higher positive and negative velocities, extending in the direction of the Homunculus axis. The He30α recombination line is also detected with the same velocity of the narrow H30α line. Finally, the close resemblance of the H30α image with that of an emission line that was reported in the literature as HCO+(4–3) led us to identify this line as H40δ instead, an identification that is further supported by modelling results. Future observations will enable to determine the proper motions of all the compact sources discovered in the new high angular resolution data of η Carinae.

scholarly journals The Molecular Outflow and CO Bullets in HH111

1997 ◽  
Vol 182 ◽  
pp. 141-152 ◽  
Author(s):  
J. Cernicharo ◽  
R. Neri ◽  
Bo Reipurth
Keyword(s):  
High Velocity ◽  
Angular Resolution ◽  
High Angular Resolution ◽  
Molecular Gas ◽  
Kinetic Temperature ◽  
Low Velocity ◽  
Molecular Outflow ◽  
Hh Objects ◽  
Physical Phenomena ◽  
First Time

We present high angular resolution observations of the molecular outflow associated with the optical jet and HH objects of the HH111 system. Interferometric observations in the CO J =2–1 and J =1–0 lines of the high velocity bullets associated with HH111 are presented for the first time. The molecular gas in these high velocity clumps has a moderate kinetic temperature and a mass of a few 10–4 M⊙ per bullet. We favor the view that HH jets and CO bullets, which represent different manifestations of the same physical phenomena, are driving the low-velocity molecular outflow.

scholarly journals Searching for kinematic evidence of Keplerian disks around Class 0 protostars with CALYPSO

2020 ◽  
Vol 635 ◽  
pp. A15 ◽  
Author(s):  
S. Maret ◽  
A. J. Maury ◽  
A. Belloche ◽  
M. Gaudel ◽  
Ph. André ◽  
...  
Keyword(s):  
Optical Thickness ◽  
Angular Resolution ◽  
Line Emission ◽  
Protoplanetary Disks ◽  
High Angular Resolution ◽  
Moment Maps ◽  
Large Program ◽  
Jet Axis

The formation of protoplanetary disks is not well understood. To understand how and when these disks are formed, it is crucial to characterize the kinematics of the youngest protostars at a high angular resolution. Here we study a sample of 16 Class 0 protostars to measure their rotation profile at scales from 50 to 500 au and search for Keplerian rotation. We used high-angular-resolution line observations obtained with the Plateau de Bure Interferometer as part of the CALYPSO large program. From 13CO (J = 2−1), C18O (J = 2−1) and SO (Nj = 56−45) moment maps, we find that seven sources show rotation about the jet axis at a few hundred au scales: SerpS-MM18, L1448-C, L1448-NB, L1527, NGC 1333-IRAS 2A, NGC 1333-IRAS 4B, and SVS13-B. We analyzed the kinematics of these sources in the uv plane to derive the rotation profiles down to 50 au scales. We find evidence for Keplerian rotation in only two sources, L1527 and L1448-C. Overall, this suggests that Keplerian disks larger than 50 au are uncommon around Class 0 protostars. However, in some of the sources, the line emission could be optically thick and dominated by the envelope emission. Due to the optical thickness of these envelopes, some of the disks could have remained undetected in our observations.

scholarly journals IRC +10 216 in 3D: morphology of a TP-AGB star envelope

2018 ◽  
Vol 610 ◽  
pp. A4 ◽  
Author(s):  
M. Guélin ◽  
N. A. Patel ◽  
M. Bremer ◽  
J. Cernicharo ◽  
A. Castro-Carrizo ◽  
...  
Keyword(s):  
Mass Loss ◽  
Angular Resolution ◽  
Binary Star ◽  
3D Structure ◽  
Line Emission ◽  
High Spectral Resolution ◽  
High Angular Resolution ◽  
Circumstellar Envelope ◽  
Outer Envelope ◽  
Radial Profiles

During their late pulsating phase, AGB stars expel most of their mass in the form of massive dusty envelopes, an event that largely controls the composition of interstellar matter. The envelopes, however, are distant and opaque to visible and NIR radiation: their structure remains poorly known and the mass-loss process poorly understood. Millimeter-wave interferometry, which combines the advantages of longer wavelength, high angular resolution and very high spectral resolution is the optimal investigative tool for this purpose. Mm waves pass through dust with almost no attenuation. Their spectrum is rich in molecular lines and hosts the fundamental lines of the ubiquitous CO molecule, allowing a tomographic reconstruction of the envelope structure. The circumstellar envelope IRC +10 216 and its central star, the C-rich TP-AGB star closest to the Sun, are the best objects for such an investigation. Two years ago, we reported the first detailed study of the CO(2–1) line emission in that envelope, made with the IRAM 30-m telescope. It revealed a series of dense gas shells, expanding at a uniform radial velocity. The limited resolution of the telescope (HPBW 11″) did not allow us to resolve the shell structure. We now report much higher angular resolution observations of CO(2–1), CO(1–0), CN(2–1) and C4H(24–23) made with the SMA, PdB and ALMA interferometers (with synthesized half-power beamwidths of 3″, 1″ and 0.3″, respectively). Although the envelope appears much more intricate at high resolution than with an 11″ beam, its prevailing structure remains a pattern of thin, nearly concentric shells. The average separation between the brightest CO shells is 16″ in the outer envelope, where it appears remarkably constant. Closer to the star (<40″), the shell pattern is denser and less regular, showing intermediary arcs. Outside the small (r< 0.3′′) dust formation zone, the gas appears to expand radially at a constant velocity, 14.5 km s-1, with small turbulent motions. Based on that property, we have reconstructed the 3D structure of the outer envelope and have derived the gas temperature and density radial profiles in the inner (r< 25′′) envelope. The shell-intershell density contrast is found to be typically 3. The over-dense shells have spherical or slightly oblate shapes and typically extend over a few steradians, implying isotropic mass loss. The regular spacing of shells in the outer envelope supports the model of a binary star system with a period of 700 yr and a near face-on elliptical orbit. The companion fly-by triggers enhanced episodes of mass loss near periastron. The densification of the shell pattern observed in the central part of the envelope suggests a more complex scenario for the last few thousand years.

scholarly journals Detection of CI line emission towards the oxygen-rich AGB star omi Ceti

2018 ◽  
Vol 612 ◽  
pp. L11 ◽  
Author(s):  
M. Saberi ◽  
W. H. T. Vlemmings ◽  
E. De Beck ◽  
R. Montez ◽  
S. Ramstedt
Keyword(s):  
Uv Radiation ◽  
Line Emission ◽  
Asymptotic Giant Branch ◽  
High Angular Resolution ◽  
Circumstellar Envelope ◽  
Velocity Shift ◽  
Compact Region ◽  
Fractional Abundance ◽  
Stellar Velocity ◽  
First Time

We present the detection of neutral atomic carbon CI(3P1–3P0) line emission towards omi Cet. This is the first time that CI is detected in the envelope around an oxygen-rich M-type asymptotic giant branch (AGB) star. We also confirm the previously tentative CI detection around V Hya, a carbon-rich AGB star. As one of the main photodissociation products of parent species in the circumstellar envelope (CSE) around evolved stars, CI can be used to trace sources of ultraviolet (UV) radiation in CSEs. The observed flux density towards omi Cet can be reproduced by a shell with a peak atomic fractional abundance of 2.4 × 10−5 predicted based on a simple chemical model where CO is dissociated by the interstellar radiation field. However, the CI emission is shifted by ~4 km s−1 from the stellar velocity. Based on this velocity shift, we suggest that the detected CI emission towards omi Cet potentially arises from a compact region near its hot binary companion. The velocity shift could, therefore, be the result of the orbital velocity of the binary companion around omi Cet. In this case, the CI column density is estimated to be 1.1 × 1019 cm−2. This would imply that strong UV radiation from the companion and/or accretion of matter between two stars is most likely the origin of the CI enhancement. However, this hypothesis can be confirmed by high-angular resolution observations.

scholarly journals The Far Ultraviolet Imaging Spectrograph on Spartan-281

1990 ◽  
Vol 139 ◽  
pp. 459-460
Author(s):  
George R. Carruthers ◽  
Harry M. Heckathorn ◽  
John C. Raymond ◽  
Reginald J. Dufour ◽  
Adolf N. Witt ◽  
...  
Keyword(s):  
Spectral Range ◽  
Angular Resolution ◽  
Hubble Space Telescope ◽  
Compact Objects ◽  
High Angular Resolution ◽  
Large Telescope ◽  
International Ultraviolet Explorer ◽  
Far Ultraviolet ◽  
Compact Sources ◽  
Imaging Spectrograph

The study of diffuse celestial sources in the ground-inaccessible ultraviolet spectral range is less advanced than UV studies of point and compact sources. The main reason is that the characteristics of instrumentation optimized for the two types of objects are quite different. Studies of diffuse objects are best made with fast focal ratio optics with wide fields of view, whereas studies of point and compact objects are best made with large telescope aperture and high angular resolution. As a result, most space ultraviolet instruments to date (such as the International Ultraviolet Explorer and the forthcoming Hubble Space Telescope) are not well suited to the study of faint, extended diffuse objects in the ultraviolet.

Constraining convection across the AGB with high-angular-resolution observations

2018 ◽  
Vol 14 (S343) ◽  
pp. 27-30
Author(s):  
Claudia Paladini ◽  
Fabien Baron ◽  
A. Jorissen ◽  
J.-B. Le Bouquin ◽  
B. Freytag ◽  
...  
Keyword(s):  
Angular Resolution ◽  
Granule Size ◽  
Scaling Relations ◽  
High Angular Resolution ◽  
Large Telescope ◽  
Horizontal Scale ◽  
Very Large Telescope ◽  
Convective Pattern ◽  
Surface Convection ◽  
First Time

AbstractWe present very detailed images of the photosphere of an AGB star obtained with the PIONIER instrument, installed at the Very Large Telescope Interferometer (VLTI). The images show a well defined stellar disc populated by a few convective patterns. Thanks to the high precision of the observations we are able to derive the contrast and granulation horizontal scale of the convective pattern for the first time in a direct way. Such quantities are then compared with scaling relations between granule size, effective temperature, and surface gravity that are predicted by simulations of stellar surface convection.

scholarly journals Classification of Wolf-Rayet stars in NGC 595 in M 33 through high-spatial resolution observations

2003 ◽  
Vol 212 ◽  
pp. 572-573 ◽  
Author(s):  
Pierre Royer ◽  
Ingemar Lundström ◽  
Jean-Marie Vreux
Keyword(s):  
Stellar Population ◽  
Angular Resolution ◽  
High Angular Resolution ◽  
Photometric Technique ◽  
H Ii Region ◽  
The One ◽  
First Time ◽  
Rayet Star

NGC 595 is, after NGC 604, the second most luminous H ii region in the Milky Way's neighbouring spiral galaxy M 33. Its Wolf-Rayet star content has mainly been unveiled by two different channels. On the one hand, the stellar population of NGC 595 has been resolved and its WR stars identified through online/off-line H ii λ4686 observations realised with the HST. Nevertheless, due to the limited number of filters used, this did not give any information on the WR spectral subtypes. On the other hand, spectroscopic observations of NGC 595, realised at optical and ultraviolet wavelengths, have enabled the determination of some spectral subtypes, but this time, the lack of angular resolution did not allow to resolve the whole population. Thanks to our photometric technique, based on five dedicated narrow-band filters, we present here a determination of the spectral subtypes of NGC 595 WR stars which for the first time combines high-angular resolution and high-‘spectroscopic’ discrimination capabilities.

New continuum and polarization observations of the Cygnus Loop with FAST I. Data processing and verification

2021 ◽  
Vol 21 (11) ◽  
pp. 282
Author(s):  
Xiao-Hui Sun ◽  
Mei-Niang Meng ◽  
Xu-Yang Gao ◽  
Wolfgang Reich ◽  
Peng Jiang ◽  
...  
Keyword(s):  
Angular Resolution ◽  
High Sensitivity ◽  
Wide Band ◽  
High Angular Resolution ◽  
Band Frequency ◽  
Cygnus Loop ◽  
Rotation Measure ◽  
Frequency Coverage ◽  
First Time ◽  
Confusion Limit

Abstract We report on the continuum and polarization observations of the Cygnus Loop supernova remnant (SNR) conducted by the Five-hundred-meter Aperture Spherical radio Telescope (FAST). FAST observations provide high angular resolution and high sensitivity images of the SNR, which will help to disentangle its nature. We obtained Stokes I, Q and U maps over the frequency range of 1.03 – 1.46 GHz split into channels of 7.63 kHz. The original angular resolution is in the range of ∼ 3 ′ − ∼ 3 ′ .8 , and we combined all the data at a common resolution of 4 ′ . The temperature scale of the total intensity and the spectral index from the in-band temperature-temperature plot are consistent with previous observations, which validates the data calibration and map-making procedures. The rms sensitivity for the band-averaged total-intensity map is about 20 mK in brightness temperature, which is at the level of confusion limit. For the first time, we apply rotation measure (RM) synthesis to the Cygnus Loop to obtain the polarization intensity and RM maps. The rms sensitivity for polarization is about 5 mK, far below the total-intensity confusion limit. We also obtained RMs of eight extragalactic sources, and demonstrate that the wide-band frequency coverage helps to overcome the ambiguity of RM determinations.

scholarly journals The Molecular Spiral Structure in M51 Derived from CO(J=2-1) Line Observations

1989 ◽  
Vol 8 ◽  
pp. 575-577 ◽  
Author(s):  
M. Guélin ◽  
S. Garcia-Burillo ◽  
R. Blundell ◽  
J. Cernicharo ◽  
D. Despois ◽  
...  
Keyword(s):  
Spiral Structure ◽  
Angular Resolution ◽  
Line Emission ◽  
High Sensitivity ◽  
High Angular Resolution ◽  
Preliminary Results

AbstractWe present preliminary results of a high angular resolution-high sensitivity survey of CO(J = 2—1) line emission in M51 made with the IRAM 30 m telescope.

Sign in / Sign up

Export Citation Format

Share Document