- ID:
- ivo://CDS.VizieR/J/A+AS/129/289
- Title:
- Long-term spectrophotometry of Be stars
- Short Name:
- J/A+AS/129/289
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The long-term spectrophotometric variations of 49 Be stars are studied using the U and V magnitudes of the UBV system, the total Balmer discontinuity D and the visible gradient {Phi}_rb_. BCD (Barbier-Chalonge-Divan, see Chalonge & Divan, 1952AnAp...15..201C) spectrophotometric and photometric data in five different photometric systems, obtained in most cases since 1950 and reduced to the BCD system, were used. The (U,D), (V,D), ({Phi}_rb_,D) and ({Phi}_rb_,V) correlations obtained differ from star to star and they can be single or double-valued. They differ clearly for Be phases or Be-shell phases. Be stars with small V.sin(i) showing the "spectrophotometric shell behaviour": D>D*, were found. This finding implies either that strongly flattened models of circumstellar envelopes are in doubt for these stars, or that not all Be stars are rapid rotators. Comparison of observed variations with those predicted for model Be stars with spherical circumstellar envelopes of variable densities and dimensions implies that spectrophotometric patterns of Be phases are due to circumstellar envelopes in low opacity regimes, while those of spectrophotometric shell phases are due to circumstellar envelopes in high opacity regimes. In a given star, the envelope regions responsible for the observed variations of D and {Phi}_rb_ in spectrophotometric shell phases seem to be smaller and denser than those producing the observed variations of these parameters in spectrophotometric Be phases. The high positive RV found in strong shell phases might favor the formation of compact circumstellar layers near the star.
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Search Results
- ID:
- ivo://CDS.VizieR/J/MNRAS/473/4130
- Title:
- M31 center emission-line point-like sources
- Short Name:
- J/MNRAS/473/4130
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a detailed description of the wavelength, astrometric and photometric calibration plan for SITELLE, the imaging Fourier transform spectrometer attached to the Canada-France-Hawaii telescope, based on observations of a red (647-685nm) data cube of the central region (11'x11') of the Andromeda galaxy. The first application, presented in this paper, is a radial-velocity catalogue (with uncertainties of ~2-6km/s) of nearly 800 emission-line point-like sources, including ~450 new discoveries. Most of the sources are likely planetary nebulae, although we also detect five novae (having erupted in the first 8 months of 2016) and one new supernova remnant candidate.
- ID:
- ivo://CDS.VizieR/J/AZh/79/328
- Title:
- Methanol maser condensations in W 48
- Short Name:
- J/AZh/79/328
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The methanol-line spectra in two maser condensations at velocities ~41 and ~45km/s in the star-forming region W 48 have been studied.
- ID:
- ivo://CDS.VizieR/J/AZh/79/610
- Title:
- Methyl acetylene observations of warm clouds
- Short Name:
- J/AZh/79/610
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The results of a survey of 63 galactic star-forming region in the 6k-5k and 5k-4k methyl acetylene lines at 102.5 and 85.5GHz are presented. Fourty-three sources were detected at 102.5GHz, and twenty-five at 85.5GHz
- ID:
- ivo://CDS.VizieR/III/207
- Title:
- Moscow Spectrophotometric Catalog (MSC)
- Short Name:
- III/207
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This catalogue contains the energy distribution of 223 stars of different spectral type and luminosity classes in the range 5975-10825{AA} with the step 50A. The observations were made at the Crimean Station of the Sternberg Astronomical Institute during 1978-1990 using near-infrared spectrophotometer installed at the 48-cm and 60-cm Zeiss reflectors. Standards are {beta} Ari, {gamma} Ori, {beta} Tau, {alpha} Leo, {eta} UMa, {alpha} Lyr, {alpha} Aql and {alpha} Peg. Energy distribution data in the spectra of standard stars was taken according to Volosina, Glushneva and Shenavrin (1980AZh....57.1003V). Monochromatic fluxes are in erg/(cm^2^.s.cm). Zero flux is expressed as 0.E+00.
- ID:
- ivo://CDS.VizieR/J/A+A/578/A22
- Title:
- Mrk421 in March 2010
- Short Name:
- J/A+A/578/A22
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A flare from the TeV blazar Mrk 421, occurring in March 2010, was observed for 13 consecutive days from radio to very high energy (VHE; E>100GeV) gamma-rays with MAGIC, VERITAS, Whipple, FermiLAT, MAXI, RXTE, Swift, GASP-WEBT, and several optical and radio telescopes. We model the day-scale SEDs with one-zone and two-zone synchrotron self-Compton (SSC) models, investigate the physical parameters, and evaluate whether the observed broadband SED variability can be associated to variations in the relativistic particle population. Flux variability was remarkable in the X-ray and VHE bands while it was minor or not significant in the other bands. The one-zone SSC model can describe reasonably well the SED of each day for the 13 consecutive days. This flaring activity is also very well described by a two-zone SSC model, where one zone is responsible for the quiescent emission while the other smaller zone, which is spatially separated from the first one, contributes to the daily-variable emission occurring in X-rays and VHE gamma-rays. Both the one-zone SSC and the two-zone SSC models can describe the daily SEDs via the variation of only four or five model parameters, under the hypothesis that the variability is associated mostly to the underlying particle population. This shows that the particle acceleration and cooling mechanism producing the radiating particles could be the main one responsible for the broadband SED variations during the flaring episodes in blazars. The two-zone SSC model provides a better agreement to the observed SED at the narrow peaks of the low- and high-energy bumps during the highest activity, although the reported one-zone SSC model could be further improved by the variation of the parameters related to the emitting region itself ({delta}, B and R), in addition to the parameters related to the particle population.
57. Mrk 926 spectra
- ID:
- ivo://CDS.VizieR/J/A+A/657/A122
- Title:
- Mrk 926 spectra
- Short Name:
- J/A+A/657/A122
- Date:
- 22 Feb 2022
- Publisher:
- CDS
- Description:
- Mrk926 is known to be a highly-variable AGN. Furthermore, it is known to show very broad-line profiles. We intended to study the continuum and line profile variations of this object with high temporal resolution in order to determine its broad-line region (BLR) structure, and to derive its black hole (BH) mass. We carried out a high-cadence spectroscopic variability campaign of Mrk926 with the 10m HET telescope, aided by photometric V-band data taken with the C18 telescope at the Wise Observatory, over a period of about five months. We extracted spectroscopic continuum and line light curves, and computed cross-correlation functions (CCFs) as well as velocity-resolved CCFs with respect to the combined spectroscopic and photometric V-band light curve. The continuum luminosity of Mrk926 showed a drastic decrease during our campaign. The luminosity dropped to less than 50% of its original luminosity within 2.5 months only. Furthermore, the spectra of Mrk926 show complex and very broad Balmer line profiles including outer Balmer satellites ranging from +/-5000 to +/-13000km/s. The integrated H{alpha}, H{beta} and HeI_5876_ line light curves are delayed relative to the continuum light curve. The Ha and Hb lines show two velocity-delay structures in the central part of their line profile (within +/-5000km/s) at ~10 and ~57 light-days, and at ~5 and ~48 light-days, respectively. These structures might be interpreted as the upper and lower half of an ellipse in the velocity-delay plane, that might be the signature of a line-emitting ring, inclined by ~50{deg} to the line of sight, orbiting the black hole at radii R of 33.5 and 26.5 light-days. We determined continuum luminosities log({lambda}*L_({lambda})_/erg/s) of 43.68 to 44.13 which are in good agreement with the established R_(BLR)-L_(AGN) relation. Adopting delays of 33.5 and 26.5 days for Ha and Hb, respectively, we derive a black hole mass of 1.1+/-0.2*10^8^M_{sun}_ which indicates a low Eddington ratio decreasing from 8 to 3 percent during our campaign. The Balmer satellite components show a higher correlation coefficient with respect to the continuum than the central line profile, and their response to the continuum variations is of the order of only 3-5 days. We attribute this to the central line segment and the Balmer satellites having different, spatially distinct regions of origin.
- ID:
- ivo://CDS.VizieR/J/A+A/608/A8
- Title:
- MUSE Hubble Ultra Deep Field Survey. VIII
- Short Name:
- J/A+A/608/A8
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the detection of 145 extended Lyman-alpha haloes around individual high-z (3-6) star-forming galaxies in the UDF field observed by MUSE/VLT. Using a 2D, two-component (continuum-like and halo) decomposition of Lyman-alpha emission assuming circular exponential distributions, we measure scale lengths and luminosities of Lyman-alpha haloes.
- ID:
- ivo://CDS.VizieR/J/A+A/633/A79
- Title:
- NGC 6240 MUSE observations
- Short Name:
- J/A+A/633/A79
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- NGC 6240 is a well-studied nearby galaxy system in the process of merging. Based on optical, X-ray, and radio observations, it is thought to harbor two active nuclei. We carried out a detailed optical 3D spectroscopic study to investigate the inner region of this system in connection with existing MERLIN and VLBA data. We observed NGC 6240 with very high spatial resolution using the MUSE instrument in the Narrow-Field Mode with the four-laser GALACSI adaptive optics system on the ESO VLT under seeing conditions of 0.49''. Our 3D spectra cover the wavelength range from 4725 to 9350 Angstroem at a spatial resolution of about 75 mas. We report the discovery of three nuclei in the final state of merging within a region of only 1 kpc in the NGC 6240 system. Thanks to MUSE we are able to show that the formerly unresolved southern component actually consists of two distinct nuclei separated by only 198pc. In combination with Gaia data we reach an absolute positional accuracy of only 30mas that is essential to compare optical spectra with MERLIN and VLBA radio positions. The verification and detailed study of a system with three nuclei, two of which are active and each with a mass in excess of 9x10^7^M_{sun}_, is of great importance for the understanding of hierarchical galaxy formation via merging processes since multiple mergers lead to a faster evolution of massive galaxies in comparison to binary mergers. So far it has been suggested that the formation of galactic nuclei with multiple supermassive black holes (SMBHs) is expected to be rare in the local universe. Triple massive black hole systems might be of fundamental importance for the coalescence of massive black hole binaries in less than a Hubble time leading to the loudest sources of gravitational waves in the megahertz regime.
- ID:
- ivo://CDS.VizieR/J/A+A/618/A3
- Title:
- NGC 300 MUSE spectroscopy for central fields
- Short Name:
- J/A+A/618/A3
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- As a new approach to the study of resolved stellar populations in nearby galaxies, we present a pilot study in NGC300 to demonstrate that integral field spectroscopy with high spatial resolution and excellent seeing conditions reaches an unprecedented depth in severely crowded fields. Observations by MUSE with seven pointings in NGC 300 have resulted in data cubes that are analyzed in four ways: (1) Point spread function-fitting 3D spectroscopy with PampelMUSE, as already successfully pioneered in globular clusters, yields de-blended spectra of individually distinguishable stars, thus providing a complete inventory of blue and red supergiants, and asymptotic giant branch (AGB) stars of type M and C. The technique is also applicable to emission line point sources and provides samples of planetary nebulae (PNe) that are complete down to m_5007_=28. (2) Pseudo-monochromatic images, created at the wavelengths of the most important emission lines and corrected for continuum light with the P3D visualization tool, provide maps of HII regions, supernova remnants (SNR), and the diffuse interstellar medium (ISM) at a high level of sensitivity, where also faint point sources stand out and allow for the discovery of PNe, Wolf-Rayet (WR) stars, etc. (3) The use of the P3D line-fitting tool yields emission line fluxes, surface brightness, and kinematic information for gaseous objects, corrected for absorption line profiles of the underlying stellar population in the case of H{alpha}. (4) Visual inspection of the data cubes by browsing through the row-stacked spectra image in P3D is demonstrated to be efficient for data mining and the discovery of background galaxies and unusual objects. We present a catalog of luminous stars, rare stars such as WR, and other emission line stars, carbon stars, symbiotic star candidates, PNe, HII regions, SNR, giant shells, peculiar diffuse and filamentary emission line objects, and background galaxies, along with their spectra. The technique of crowded-field 3D spectroscopy, using the PampelMUSE code, is capable of deblending individual bright stars, the unresolved background of faint stars, gaseous nebulae, and the diffuse component of the ISM, resulting in unprecedented legacy value for observations of nearby galaxies with MUSE.
