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241. Best-fit emission-line properties in NGC 5775
ID:
ivo://CDS.VizieR/J/ApJ/885/160
Title:
Best-fit emission-line properties in NGC 5775
Short Name:
J/ApJ/885/160
Date:
08 Mar 2022
Publisher:
CDS
Description:
The structure and kinematics of gaseous, disk-halo interfaces are imprinted with the processes that transfer mass, metals, and energy between galactic disks and their environments. We study the extraplanar diffuse ionized gas (eDIG) layer in the interacting, star-forming galaxy NGC5775 to better understand the consequences of star formation feedback on the dynamical state of the thick-disk interstellar medium. Combining emission-line spectroscopy from the Robert Stobie Spectrograph on the Southern African Large Telescope with radio continuum observations from Continuum Halos in Nearby Galaxies-an EVLA Survey, we ask whether thermal, turbulent, magnetic field, and cosmic-ray pressure gradients can stably support the eDIG layer in dynamical equilibrium. This model fails to reproduce the observed exponential electron scale heights of the eDIG thick disk and halo on the northeast (h_z,e_=0.6,7.5kpc) and southwest (h_z,e_=0.8,3.6kpc) sides of the galaxy at R<11kpc. We report the first definitive detection of an increasing eDIG velocity dispersion as a function of height above the disk. Blueshifted gas along the minor axis at large distances from the midplane hints at a disk-halo circulation and/or ram pressure effects caused by the ongoing interaction with NGC5774. This work motivates further integral field unit and/or Fabry-Perot spectroscopy of galaxies with a range of star formation rates to develop a spatially resolved understanding of the role of star formation feedback in shaping the kinematics of the disk-halo interface.
242. beta Pic HARPS spectrum
ID:
ivo://CDS.VizieR/J/A+A/607/A25
Title:
beta Pic HARPS spectrum
Short Name:
J/A+A/607/A25
Date:
21 Oct 2021
Publisher:
CDS
Description:
The young planetary system beta Pictoris is surrounded by a circumstellar disk of dust and gas. Because both dust and gas have a lifetime shorter than the system age, they need to be replenished continuously. The gas composition is partly known, but its location and its origin are still a puzzle. The gas source could be the exocomets (or so-called falling and evaporating bodies, FEBs), which are observed as transient features in absorption lines of refractory elements (Mg, Ca, and Fe) when they transit in front of the star at several tens of stellar radii. Nearly 1700 high-resolution spectra of beta Pictoris have been obtained from 2003 to 2015 using the HARPS spectrograph. In these spectra, the circumstellar disk is always detected as a stable component among the numerous variable absorption signatures of transiting exocomets. Summing all the 1700 spectra allowed us to reach a signal-to-noise ratio higher than 1000, which is an unprecedentedly high number for a beta Pictoris spectrum. It revealed many weak Fe I absorption lines of the circumstellar gas in more than ten excited states. These weak lines bring new information on the physical properties of the neutral iron gas in the circumstellar disk. The population of the first excited levels follows a Boltzmann distribution with a slope consistent with a gas temperature of about 1300K; this temperature corresponds to a distance to the star of ~38 R_star_ and implies a turbulence of ksi~0.8km/s.
243. Beta Pictoris 1994-96
ID:
ivo://CDS.VizieR/J/MNRAS/304/733
Title:
Beta Pictoris 1994-96
Short Name:
J/MNRAS/304/733
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present high-resolution spectroscopy of the variable CaII H & K absorptions in the star Beta Pictoris. 313 spectra were obtained on 53 nights between 1994 November and 1996 December in order to characterize the lines' behaviour and to test the Falling Evaporating Bodies (FEB) scenario. Near-continuous absorption activity was seen, including blue-shifted features, one of which rivalled the strength of that reported in 1997 June by Crawford et al. (1998MNRAS.294L..31C). Redshifted features at ~5-20km/s were present until the end of 1995 and are evocative of a year-long stream of infalling bodies with typically 4-5 objects in the line of sight. At higher velocities, features were shorter lived and generally broader and shallower. These correlations also apply to blue-shifted features. On 1995 June 9 we detected a probably narrow, short-lived feature at a redshift of ~130km/s. The FEB models predict that the strength of the H line may exceed the K line value as a body tracks across the stellar disc, but we have no convincing observation of this, though we did observe some events where the H & K absorptions evolved differently.
244. beta Pictoris 1997 and 1998 spectra
ID:
ivo://CDS.VizieR/J/MNRAS/489/574
Title:
beta Pictoris 1997 and 1998 spectra
Short Name:
J/MNRAS/489/574
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present spectroscopy with resolution R~33000 of the circumstellar CaII H & K absorptions in the star beta Pictoris during 1997 and 1998. From 1997 April onwards, both lines were observed simultaneously. A total of 688 spectra were obtained on 95 nights in order to characterize the lines' behaviour. Near-continuous Falling Evaporating Body (FEB) variable absorption activity was seen, including additional strong, blue-shifted features besides the one on 1997 June 19-20 already reported by others. Temporal coverage is more even than in the HARPS spectra from 2004-11 that have been analysed for FEB orbital parameters via a model of FEB evaporation. Our observations likely encompass the 1997-98 Hill-sphere transit by beta Pic b, but we have found no clear signature of transiting material. Lower-velocity FEB absorptions tend to be deeper, narrower and longer lived, in confirmation of earlier studies. The ratio of line strengths for one absorption on 1998 November 27 is evocative of the variations expected for a single FEB making a transit perpendicular to the stellar rotation axis. Analysis with the evaporation model produces similar distributions of orbital parameters to those obtained from the HARPS observations, but when the derived orbital parameters are fed into a model based solely on gravitational dynamics of point masses, the predicted FEB accelerations do not agree with observed values. More sophisticated modelling is called for. There is no convincing intrinsic variation in the central circumstellar absorption such as might be expected if an HI ring is responsible for the confinement of circumstellar Ca^+^ ions. Our observations are available electronically for further analysis by others.
245. BF Cyg 2006 outburst spectrum
ID:
ivo://CDS.VizieR/J/PASP/123/1062
Title:
BF Cyg 2006 outburst spectrum
Short Name:
J/PASP/123/1062
Date:
21 Oct 2021
Publisher:
CDS
Description:
BF Cygni (hereafter BF Cyg) is a symbiotic star that in 2006 July started into an optical outburst that has lasted for several years. Between 2006 August and 2007 January we obtained high-dispersion spectra (r~35,000) over the wavelength range of 3800-10000{AA} of BF Cyg with the 3.5m echelle spectrograph at Apache Point Observatory. The emission lines in the optical spectrum of BF Cyg changed dramatically during the interval of observations. The species found were mostly low-ionization emission lines of H, He, C, N, O, Mg, Si, Ca, Sc, Ti, V, Cr, Mn, Fe, and Ni. Both permitted and forbidden lines were seen. In particular, Fe I was observed in emission, which is not a common phenomenon.
246. BH masses and Eddington ratios of Type 2 QSOs
ID:
ivo://CDS.VizieR/J/ApJ/859/116
Title:
BH masses and Eddington ratios of Type 2 QSOs
Short Name:
J/ApJ/859/116
Date:
21 Oct 2021
Publisher:
CDS
Description:
Type 2 quasars are an important constituent of active galaxies, possibly representing the evolutionary precursors of traditionally studied type 1 quasars. We characterize the black hole (BH) mass (MBH) and Eddington ratio (Lbol/LEdd) for 669 type 2 quasars selected from the Sloan Digital Sky Survey, using BH masses estimated from the MBH-{sigma}* relation and bolometric corrections scaled from the extinction-corrected [OIII]{lambda}5007 luminosity. When stellar velocity dispersions cannot be measured directly from the spectra, we estimate them from the core velocity dispersions of the narrow emission lines [OII]{lambda}{lambda}3726,3729, [SII]{lambda}{lambda}6716,6731, and [OIII]{lambda}5007, which are shown to trace the gravitational potential of the stars. Energy input from the active nucleus still imparts significant perturbations to the gas kinematics, especially to high-velocity, blueshifted wings. Nonvirial motions in the gas become most noticeable in systems with high Eddington ratios. The BH masses of our sample of type 2 quasars range from MBH~10^6.5^ to 10^10.4^M_{sun}_ (median 10^8.2^M_{sun}_). Type 2 quasars have characteristically large Eddington ratios (Lbol/LEdd~10^-2.9^-10^1.8^; median 10^-0.7^), slightly higher than in type 1 quasars of similar redshift; the luminosities of ~20% of the sample formally exceed the Eddington limit. The high Eddington ratios may be consistent with the notion that obscured quasars evolve into unobscured quasars.
247. Binaries in the Praesepe and Coma clusters
ID:
ivo://CDS.VizieR/J/ApJ/521/682
Title:
Binaries in the Praesepe and Coma clusters
Short Name:
J/ApJ/521/682
Date:
21 Oct 2021
Publisher:
CDS
Description:
This completes a study of the evolution of binary systems in five open clusters of various ages. Among 21 stars observed in Praesepe, eight are found or confirmed to be spectroscopic binaries and orbital elements are derived, while one more shows long-term binary motion. Among 18 stars observed in the Coma Berenices cluster, five are found or confirmed to be spectroscopic binaries and orbital elements are derived, while a sixth has tentative elements.
248. Binary central stars of SMC PNe
ID:
ivo://CDS.VizieR/J/A+A/561/A8
Title:
Binary central stars of SMC PNe
Short Name:
J/A+A/561/A8
Date:
21 Oct 2021
Publisher:
CDS
Description:
The Optical Gravitational Lensing Experiment (OGLE), originally designed to search for microlensing events, provides a rich and uniform data set suitable for studying the variability of certain types of objects. We used the OGLE data to study the photometry of central stars of planetary nebulae (PNe) in the Small Magellanic Cloud (SMC). In particular, we searched for close binary central stars with the aim to constrain the binary fraction and period distribution in the SMC. We also searched for PNe mimics and removed them from the PNe sample. We identified 52 counterparts of PNe in the SMC in the I-band images from the OGLE-II and OGLE-III surveys. We analysed the time-series photometry of the PNe. Spectra of the photometric variables were obtained to constrain the nature of the objects or search for additional evidence for binarity. Eight variables were found. Of these, seven objects are PNe mimics, including one symbiotic star candidate. One close binary central star of PN with a period of 1.15 or 2.31 day was discovered. The obtained binary fraction for the SMC PNe and the observational biases are discussed in terms of the OGLE observations.
249. Binary red supergiants. II. B-type companions
ID:
ivo://CDS.VizieR/J/ApJ/875/124
Title:
Binary red supergiants. II. B-type companions
Short Name:
J/ApJ/875/124
Date:
20 Jan 2022 11:13:46
Publisher:
CDS
Description:
The percentage of massive main-sequence OB stars in binary systems is thought to be as high as 100%. However, very few Galactic binary red supergiants (RSGs) have been identified, despite the fact that these stars are the evolved descendants of OB stars. As shown in our recent paper, binary RSGs will likely have B-type companions, as dictated by stellar evolution considerations. Such a system will have a very unique photometric signature due to the shape of the spectral energy distribution. Using photometric cutoffs, it should therefore be possible to detect candidate RSG+B star binary systems. Here we present our spectroscopic follow-up observations of such candidates. Out of our initial list of 280 candidates in M31 and M33, we observed 149 and confirmed 63 as newly discovered RSG+B star binary systems. Additional spectra of four candidate systems in the Small Magellanic Cloud confirmed all of them as new RSG+B star binaries including the first known RSG+Be star system. By fitting BSTAR06 and MARCS model atmospheres to the newly obtained spectra, we place estimates on the temperatures and subtypes of both the B stars and RSGs. Overall, we have found 87 new RSG+B star binary systems in M31, M33 and the Small and Large Magellanic Clouds. Our future studies are aimed at determining the binary fraction of RSGs.
250. Binary stars parameters from LAMOST & Kepler obs.
ID:
ivo://CDS.VizieR/J/ApJS/244/43
Title:
Binary stars parameters from LAMOST & Kepler obs.
Short Name:
J/ApJS/244/43
Date:
21 Oct 2021
Publisher:
CDS
Description:
The parameter distribution of binaries is a fundamental knowledge of the stellar systems. A statistical study on the binary stars is carried out based on the LAMOST spectral and Kepler photometric database. We presented a catalog of 1320 binary stars with plentiful parameters, including period, binary subtype, atmosphere parameters (Teff, [Fe/H], and logg), and the physical properties, such as mass, radius, and age, for the primary component stars. Based on this catalog, the unbiased distribution, rather than the observed distribution, was obtained after the correction of selection biases by the Monte Carlo method considering comprehensive affecting factors. For the first time, the orbital eccentricity distribution of the detached binaries is presented. The distribution differences between the three subtypes of binaries (detached, semidetached, and contact) are demonstrated, which can be explained by the generally accepted evolutional scenarios. Many characteristics of the binary stars, such as huge mass transfer on semidetached binaries, period cutoff on contact binaries, period-temperature relationship of contact binaries, and the evolved binaries, are reviewed by the new database. This work supports a common evolutionary scenario for all subtypes of binary stars.

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