- ID:
- ivo://CDS.VizieR/J/ApJ/698/1682
- Title:
- Most luminous dusty galaxies
- Short Name:
- J/ApJ/698/1682
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A summary of mid-infrared continuum luminosities arising from dust is given for very luminous galaxies, L_IR_>10^12^L_{sun}_, with 0.005<z<3.2 containing active galactic nuclei (AGNs), including 115 obscured AGNs and 60 unobscured (type 1) AGNs. All sources have been observed with the Spitzer Infrared Spectrograph. Obscured AGNs are defined as having optical depth {tau}>0.7 in the 9.7um silicate absorption feature (i.e., half of the continuum is absorbed) and having equivalent width of the 6.2um polycyclic aromatic hydrocarbon feature <0.1um (to avoid sources with a significant starburst component). Unobscured AGNs are defined as those that show silicate in emission. Luminosity {nu}L_{nu}_(8um) for the most luminous obscured AGNs is found to scale as (1+z)^2.6^ to z=2.8. For unobscured AGNs, the scaling with redshift is similar, but luminosities {nu}L_{nu}_(8um) are approximately three times greater for the most luminous sources. Using both obscured and unobscured AGNs having total infrared fluxes from the Infrared Astronomical Satellite, empirical relations are found between {nu}L_{nu}_(8um) and L_IR_.
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Search Results
- ID:
- ivo://CDS.VizieR/J/ApJ/886/40
- Title:
- Most luminous SPIRITS IR transients follow-up obs.
- Short Name:
- J/ApJ/886/40
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a systematic study of the most luminous (MIR [Vega magnitudes] brighter than -14) infrared (IR) transients discovered by the SPitzer InfraRed Intensive Transients Survey (SPIRITS) between 2014 and 2018 in nearby galaxies (D<35Mpc). The sample consists of nine events that span peak IR luminosities of M_[4.5],peak_ between -14 and -18.2, show IR colors between 0.2<([3.6]-[4.5])<3.0, and fade on timescales between 55d<t_fade_<480d. The two reddest events (A_V_>12) show multiple, luminous IR outbursts over several years and have directly detected, massive progenitors in archival imaging. With analyses of extensive, multiwavelength follow-up, we suggest the following possible classifications: five obscured core-collapse supernovae (CCSNe), two erupting massive stars, one luminous red nova, and one intermediate-luminosity red transient. We define a control sample of all optically discovered transients recovered in SPIRITS galaxies and satisfying the same selection criteria. The control sample consists of eight CCSNe and one Type Iax SN. We find that 7 of the 13 CCSNe in the SPIRITS sample have lower bounds on their extinction of 2<A_V_<8. We estimate a nominal fraction of CCSNe in nearby galaxies that are missed by optical surveys as high as 38.5_-21.9_^+26.0^% (90% confidence). This study suggests that a significant fraction of CCSNe may be heavily obscured by dust and therefore undercounted in the census of nearby CCSNe from optical searches.
- ID:
- ivo://CDS.VizieR/J/A+A/483/903
- Title:
- Mount Wilson index for main sequence F-K stars
- Short Name:
- J/A+A/483/903
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The largest dataset of stellar activity measurements available at present is the one obtained at the Mount Wilson Observatory, where high-precision CaII H+K fluxes have been measured from 1966 for about 2200 stars. Since the MgII H and K lines at {lambda}2800{AA} are formed in a similar way to the CaII H+K emission lines, they are also good indicators of chromospheric structure. The International Ultraviolet Explorer (IUE) provides a large database of UV spectra in the band 1150-3350{AA} from 1978 to 1995, which can also be used to study stellar activity. The main purpose of this study is to use the IUE spectra in the analysis of magnetic activity of main sequence F-K stars. Combining IUE observations of MgII and optical spectroscopy of CaII, the registry of activity of stars can be extended in time.
- ID:
- ivo://CDS.VizieR/J/AJ/124/234
- Title:
- M31 outer halo UBVRI photometry and metallicity
- Short Name:
- J/AJ/124/234
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present first results from a spectroscopic survey designed to examine the metallicity and kinematics of individual red giant branch stars in the outer halo of the Andromeda spiral galaxy (M31). This study is based on multislit spectroscopy with the Keck II 10m telescope and Low Resolution Imaging Spectrograph of the Ca II near-infrared triplet in 99 M31 halo candidates in a field at R=19kpc on the southeast minor axis with brightnesses from 20<I<22.
- ID:
- ivo://CDS.VizieR/J/MNRAS/426/416
- Title:
- Mrk 6 H{alpha}, H{beta} and H{gamma} spectra
- Short Name:
- J/MNRAS/426/416
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results of optical spectral and photometric observations of the nucleus of Markarian 6 made with the 2.6-m Shajn telescope at the Crimean Astrophysical Observatory. The continuum and emission Balmer-line intensities varied by more than a factor of two during 1992-2008. The lag between the continuum and H{beta} emission-line flux variations is 21.1+/-1.9days. For the H{alpha} line the lag is about 27-days, but its uncertainty is much larger.
1646. Mrk421 in March 2010
- 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.
- ID:
- ivo://CDS.VizieR/J/A+A/561/A64
- Title:
- Mrk 996 optical spectroscopy
- Short Name:
- J/A+A/561/A64
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present an integral field spectroscopic study with the Gemini Multi-Object Spectrograph (GMOS) of the unusual blue compact dwarf (BCD) galaxy Mrk 996. We show through velocity and dispersion maps, emission-line intensity and ratio maps, and by a new technique of electron density limit imaging that the ionization properties of different regions in Mrk 996 are correlated with their kinematic properties.
1648. 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/MNRAS/355/1196
- Title:
- MS bands of SiC_2_ in LMC carbon stars
- Short Name:
- J/MNRAS/355/1196
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- From a sample of 304 carbon stars in the central parts of the Large Magellanic Cloud (LMC), ~27 per cent have Merrill-Sanford (MS) bands of the SiC2 molecule. The data are based on a uniform set of spectra taken with 2dF on the Anglo-Australian Telescope, and give useful statistics on the incidence of MS bands and on their correlation (or otherwise) with other properties. All of these are red stars, cooler than 3100 K. The proportion of stars showing the bands is highest amongst the coolest stars, but not all very cool stars show the bands. There is no evidence that MS bands are more common in J-type stars (carbon stars with a high ^13^C/^12^C ratio) than in N-type carbon stars, at least within this sample of LMC stars. There is no apparent correlation with stellar variability, or between the photospheric temperature [as measured by (J-K)] and the occurrence of the 'hot' MS bands from excited molecular states.
1650. M82 spectral maps
- ID:
- ivo://CDS.VizieR/J/A+A/578/A49
- Title:
- M82 spectral maps
- Short Name:
- J/A+A/578/A49
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- M82 is one of the nearest and brightest starburst galaxies. It has been extensively studied in the past decade and by now is considered the prototypical extragalactic photon-dominated region (PDR) and a reference for studying star formation feedback. Our aim is to characterize the molecular chemistry in M82 at spatial scales of giant molecular clouds (GMCs), ~100pc, to investigate the feedback effects of the star formation activity.
