- ID:
- ivo://CDS.VizieR/J/A+A/575/A17
- Title:
- NGC 891 Herschel PACS and SPIRE spectroscopy
- Short Name:
- J/A+A/575/A17
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present Herschel PACS and SPIRE spectroscopy of the most important far- infrared cooling lines in the nearby edge-on spiral galaxy, NGC 891: the [CII] 158, [NII] 122, 205, [OI] 63, 145, and [OIII] 88 micron lines. We find that the photoelectric heating efficiency of the gas varies from a mean of 3.5x10^-3^ in the centre up to 8x10^-3^ at increasing radial and vertical distances in the disc. We compare the observed flux of the FIR cooling lines and total IR emission with the predicted flux from a PDR model to determine the gas density, surface temperature and the strength of the incident far-ultraviolet (FUV) radiation field, G_0_. Resolving details on physical scales of ~0.6kpc, a pixel-by-pixel analysis reveals that the majority of the PDRs in NGC 891's disc have hydrogen densities of 1<log(n/cm^-3^)<3.5 experiencing an incident FUV radiation field with strengths of 1.7<logG_0_<3. Although these values we derive for most of the disc are consistent with the gas properties found in PDRs in the spiral arms and inter-arm regions of M51, observed radial trends in n and G_0_ appear to be sensitive to varying optical thickness in the lines, demonstrating the importance of accurately accounting for optical depth effects when interpreting observations of high inclination systems. With an empirical relationship between the MIPS 24 micron and [NII] 205 micron emission, we estimate an enhancement of the FUV radiation field strength in the far north-eastern side of the disc.
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Search Results
- ID:
- ivo://CDS.VizieR/J/A+A/558/A87
- Title:
- NGC6240 high resolution mapping of CO(1-0)
- Short Name:
- J/A+A/558/A87
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present long baseline CO(1-0) mapping of the luminous infrared galaxy NGC 6240 obtained with the IRAM - Plateau de Bure Interferometer. This source is a well known early-stage merging system hosting two active galactic nuclei (AGN). We find a broad CO(1-0) line profile with maximum velocity 800km/s and a total line width of 1400km/s that displays several kinematic components, revealing the complexity of the gas dynamics in this system. We detect a blueshifted CO emission with velocity between -200 and -500 km/s, which peaks around the southern AGN at the same position where the H_2_ outflow is located. We interpret this blueshifted component as an outflow with a mass loss rate of ~500M_{sun}_/yr, originating from the southern nucleus.
2583. NGC 628 H II regions
- ID:
- ivo://CDS.VizieR/J/AJ/120/1306
- Title:
- NGC 628 H II regions
- Short Name:
- J/AJ/120/1306
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Employing deep H{alpha} narrowband imagery, we identified and measured the fluxes of 137 small H II regions in the extreme outer disk (R>=R_25_) of the nearly face-on, Sc I galaxy NGC 628. A majority of these H II regions are located in two faint, outer spiral arms visible in H I maps. The faintest H II regions that could be measured have fluxes of only a few times 10^-16^ergs/cm^2^/s, which correspond to luminosities of 10^36^ergs/s, or a fraction of the Orion Nebula luminosity. The most distant object detected is at R~27kpc from the galaxy center. The massive star formation rate, as measured from the azimuthally averaged H{alpha} flux, is consistent with a monotonic decrease as far as R~1.3R_25_ (20kpc), where there is a sharp drop. The Schmidt law for the whole disk of NGC 628 corresponds to a relatively steep power law with n=2.9+/-0.2, but it "fails" below {Sigma}gas<=4M_{sun}_/pc^2^; the index depends strongly on the CO data used. We derived the luminosity function (LF) of 598 H II regions over the whole disk, and we compared the shapes of the cumulative LFs between R>=R_25_ and R<R_25_; the LF of the outer regions is significantly steeper than that of the inner regions.
- ID:
- ivo://CDS.VizieR/J/A+A/551/A81
- Title:
- NGC 6951 intensity and velocity maps
- Short Name:
- J/A+A/551/A81
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Gas inflowing along stellar bars is often stalled at the location of circumnuclear rings, which form an effective reservoir for massive star formation and thus shape the central regions of galaxies. However, how exactly star formation proceeds within these circumnuclear starburst rings is the subject of debate. Two main scenarios for this process have been put forward. In the first, the onset of star formation is regulated by the total amount of gas present in the ring with star forming starting, once a mass threshold has been reached, in "random" positions within the ring like "popcorn". In the second, star formation primarily takes place near the locations where the gas enters the ring. This scenario has been dubbed "pearls-on-a-string". Here we combine new optical IFU data covering the full stellar bar with existing multiwavelength data to study the 580pc radius circumnuclear starburst ring in detail in the nearby spiral galaxy NGC 6951. Using Hubble Space Telescope (HST) archival data together with SAURON and OASIS IFU data, we derive the ages and stellar masses of star clusters, as well as the total stellar content of the central region.
- ID:
- ivo://CDS.VizieR/J/A+AS/131/105
- Title:
- NGC 6221 ionized gas kinematics
- Short Name:
- J/A+AS/131/105
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Rotation curves and velocity dispersion profiles are presented for both the stellar and gaseous components along five different position angles (PA =5{deg}, 50{deg}, 95{deg}, 125{deg}, and 155{deg}) of the nearby barred spiral NGC 6221. The observed kinematics extends out to about 80'' from the nucleus. Narrow and broad-band imaging is also presented. The radial profiles of the fluxes ratio [NII] ({lambda} 6583.4{AA})/H{alpha} reveal the presence of a ring-like structure of ionized gas, with a radius of about 9'' and a deprojected circular velocity of about 280km/s. The analysis of the dynamics of the bar indicates this ring is related to the presence of an inner Lindblad resonance (ILR) at 1.3kpc. NGC 6221 is found to exhibit intermediate properties between those of the early-type barred galaxies: the presence of a gaseous ring at an ILR, the bar edge located between the ILR's and the corotation radius beyond the steep rising portion of the rotation curve, the dust-lane pattern, and those of the late-type galaxies: an almost exponential surface brightness profile, the presence of H{alpha} regions along all the bar, the spiral-arm pattern. It is consistent with scenarios of bar-induced evolution from later to earlier-type galaxies.
2586. NGC4395 light curves
- ID:
- ivo://CDS.VizieR/J/ApJ/632/799
- Title:
- NGC4395 light curves
- Short Name:
- J/ApJ/632/799
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A reverberation-mapping program on NGC 4395, the least luminous known Seyfert 1 galaxy, undertaken with the Space Telescope Imaging Spectrograph on the Hubble Space Telescope yields a measurement of the mass of the central black hole M_BH_=(3.6+/-1.1)x10^5^M_{sun}_. The observations consist of two visits of five orbits each, in 2004 April and July. During each of these visits, the UV continuum varied by at least 10% (rms), and only C IV {lambda}1549 showed corresponding variations large enough to reliably determine the emission-line lag, which was measured to be of order 1-hr for both visits.
- ID:
- ivo://CDS.VizieR/J/ApJ/650/88
- Title:
- NGC4395 light curves. III.
- Short Name:
- J/ApJ/650/88
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present optical observations of the low-luminosity Seyfert 1 nucleus of NGC 4395, as part of a multiwavelength reverberation-mapping program. Observations were carried out over two nights in 2004 April at Lick, Wise, and Kitt Peak Observatories. We obtained V- and B-band photometry, and spectra over the range 3500-6800{AA}. Simultaneous Hubble Space Telescope UV and Chandra X-ray observations are presented in companion papers.
- ID:
- ivo://CDS.VizieR/J/A+A/324/904
- Title:
- NGC 4151 line-continuum diagram sequences
- Short Name:
- J/A+A/324/904
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the first results of an 8-year spectroscopic monitoring of the Seyfert 1.5 galaxy NGC 4151 carried out with a CCD spectrograph at the 2.6-m Shajn Telescope of the Crimean Astrophysical Observatory in 1988-1995. Total of 202 H{ alpha} region spectra and 154 H{beta} region spectra have formed the data set. A ll spectra were calibrated in flux using the narrow emission lines which were as summed to be constant over the duration of the monitoring program.
2589. NGC 4565 LOFAR images
- ID:
- ivo://CDS.VizieR/J/A+A/628/L3
- Title:
- NGC 4565 LOFAR images
- Short Name:
- J/A+A/628/L3
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Cosmic rays play a pivotal role in launching galactic winds, particularly in quiescently star-forming galaxies where the hot gas alone is not sufficient to drive a wind. Except for the Milky Way, not much is known about the transport of cosmic rays in galaxies. In this Letter, we present low-frequency observations of the nearby edge-on spiral galaxy NGC 4565 using the LOw-Frequency ARray (LOFAR). With our deep 144-MHz observations, we obtain a clean estimate of the emission originating from old cosmic-ray electrons (CRe), which is almost free from contamination by thermal emission. We measured vertical profiles of the non-thermal radio continuum emission that we fitted with Gaussian and exponential functions. The different profile shapes correspond to 1D cosmic-ray transport models of pure diffusion and advection, respectively. We detect a warp in the radio continuum that is reminiscent of the previously known HI warp. Because the warp is not seen at GHz-frequencies in the radio continuum, its minimum age must be about 100Myr. The warp also explains the slight flaring of the thick radio disc that can otherwise be well described by a Gaussian profile with an FWHM of 65-arcsec (3.7kpc). The diffusive radio halo together with the extra-planar X-ray emission may be remnants of enhanced star-forming activity in the past where the galaxy had a galactic wind, as GHz-observations indicate only a weak outflow in the last 40Myr. NGC 4565 could be in transition from an outflow- to an inflow-dominated phase.
2590. NGC 3923 MegaCam image
- ID:
- ivo://CDS.VizieR/J/A+A/588/A77
- Title:
- NGC 3923 MegaCam image
- Short Name:
- J/A+A/588/A77
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The elliptical galaxy NGC 3923 is known to be surrounded by a number of stellar shells, probable remnants of an accreted galaxy. Despite its uniqueness, the deepest images of its outskirts come from the 1980s. On the basis of the modified Newtonian dynamics (MOND), it has recently been predicted that a new shell lies in this region. We obtain the deepest image ever of the galaxy, map the tidal features in it, and search for the predicted shell. The image of the galaxy was taken by the MegaCam camera at the Canada-France-Hawaii Telescope in the g'-band. It reached the surface-brightness limit of 29mag/arcsec^2^. In addition, we reanalyzed an archival HST image of the galaxy.