- ID:
- ivo://CDS.VizieR/J/A+A/555/A142
- Title:
- Spectra of 5 Type II supernovae
- Short Name:
- J/A+A/555/A142
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Core-collapse Supernovae (CC-SNe) descend from progenitors more massive than about 8M_{sun}_. Because of the young age of the progenitors, the ejecta may eventually interact with the circumstellar medium (CSM) via highly energetic processes detectable in the radio, X-ray, ultraviolet (UV) and, sometimes, in the optical domains. In this paper we present ultraviolet, optical and near infrared observations of five type II SNe, namely SNe 2009dd, 2007pk, 2010aj, 1995ad, and 1996W. Together with few other SNe they form a group of moderately luminous type II events. We investigate the photometric similarities and differences among these bright objects. We also attempt to characterise them by analysing the spectral evolutions, in order to find some traces of CSM-ejecta interaction. We collected photometry and spectroscopy with several telescopes in order to construct well-sampled light curves and spectral evolutions from the photospheric to the nebular phases. Both photometry and spectroscopy indicate a degree of heterogeneity in this sample. Modelling the data of SNe 2009dd, 2010aj and 1995ad allows us to constrain the explosion parameters and the properties of the progenitor stars. The light curves have luminous peak magnitudes (-16.95<M_B}_-18.70). The ejected masses of ^56^Ni for three SNe span a wide range of values (2.8x10^-2^M_{sun}<M(^56^Ni)<1.4x10^-1^M_{sun}_), while for a fourth (SN2010aj) we could determine a stringent upper limit (7x10^-3^M_{sun}_). Clues of interaction, such as the presence of high velocity (HV) features of the Balmer lines, are visible in the photospheric spectra of SNe 2009dd and 1996W. For SN2007pk we observe a spectral transition from a type IIn to a standard type II SN. Modelling the observations of SNe 2009dd, 2010aj and 1995ad with radiation hydrodynamics codes, we infer kinetic plus thermal energies of about 0.2-0.5 foe, initial radii of 2-5x10^13^cm and ejected masses of ~5.0-9.5M_{sun}_. These values suggest moderate-mass, super-asymptotic giant branch (SAGB) or red super-giants (RSG) stars as SN precursors, in analogy with other luminous type IIP SNe 2007od and 2009bw.
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Search Results
- ID:
- ivo://CDS.VizieR/J/ApJ/690/1358
- Title:
- Spectra of unusual optical transient SCP 06F6
- Short Name:
- J/ApJ/690/1358
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present observations of SCP 06F6, an unusual optical transient discovered during the Hubble Space Telescope Cluster Supernova Survey. The transient brightened over a period of ~100 days, reached a peak magnitude of ~21.0 in both i_775_ and z_850_, and then declined over a similar timescale. There is no host galaxy or progenitor star detected at the location of the transient to a 3{sigma} upper limit of i_775_>=26.4 and z_850_>=26.1, giving a corresponding lower limit on the flux increase of a factor of ~120. Multiple spectra show five broad absorption bands between 4100{AA} and 6500{AA}, and a mostly featureless continuum longward of 6500{AA}. The shape of the light curve is inconsistent with microlensing. The transient's spectrum, in addition to being inconsistent with all known supernova types, does not match any spectrum in the Sloan Digital Sky Survey database. We suggest that the transient may be one of a new class.
- ID:
- ivo://CDS.VizieR/J/AJ/146/68
- Title:
- Spectra of Vega, Sirius, GD153, and HD209458
- Short Name:
- J/AJ/146/68
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This paper extends synthetic photometry to components of binary star systems. The paper demonstrates accurate recovery of single star photometric properties for four photometric standards, Vega, Sirius, GD153, and HD209458, ranging over the HR diagram, when their model synthetic spectra are placed in fictitious binary systems and subjected to synthetic photometry processing. Techniques for photometric distance determination have been validated for all four photometric standards.
- ID:
- ivo://CDS.VizieR/J/A+A/569/A120
- Title:
- Spectra of wide companions to planet-host stars
- Short Name:
- J/A+A/569/A120
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results of a search for wide companions to planet-host stars to improve our knowledge on their multiplicity at wide physical separations. We cross-matched approximately 6200 square degree area of the Southern sky imaged by the Visible Infrared Survey Telescope for Astronomy (VISTA) Hemisphere Survey (VHS) with the Two Micron All Sky Survey (2MASS) to look for wide common proper motion companions to known planet-host stars. We complemented our astrometric search with photometric criteria. We confirmed spectroscopically the co-moving nature of seven sources out of 16 companion candidates and discarded eight, while the remaining one stays as a candidate. Among these new wide companions to planet-host stars, we discovered a T4.5 dwarf companion at 6.3-arcmin (~9000AU) from HIP70849, a K7V star which hosts a 9 Jupiter mass planet with an eccentric orbit. We also report two new stellar M dwarf companions to one G and one metal-rich K star. We infer stellar and substellar binary frequencies for our complete sample of 37 targets of 5.4+/-3.8% and 2.7+/-2.7% (1 sigma confidence level), respectively, for projected physical separations larger than ~60-160AU assuming the range of distances of planet-host stars (24-75pc). These values are comparable to the frequencies of non planet-host stars. We find that the period-eccentricity trend holds with a lack of multiple systems with planets at large eccentricities (e>0.2) for periods less than 40-days. However, the lack of planets more massive than 2.5 Jupiter masses and short periods (<40-days) orbiting single stars is not so obvious due to recent discoveries by ground-based transit surveys and space missions.
- ID:
- ivo://CDS.VizieR/J/A+A/589/A16
- Title:
- Spectra of W49 massives young stars
- Short Name:
- J/A+A/589/A16
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Massive stars form on different scales ranging from large, dispersed OB associations to compact, dense starburst clusters. The complex structure of regions of massive star formation, and the involved short timescales provide a challenge for our understanding of their birth and early evolution. As one of the most massive and luminous star- forming region in our Galaxy, W49 is the ideal place to study the formation of the most massive stars. By classifying the massive young stars deeply embedded into the molecular cloud of W49, we aim to investigate and trace the star formation history of this region. We analyse near-infrared K-band spectroscopic observations of W49 from LBT/LUCI combined with JHK images obtained with NTT/SOFI and LBT/LUCI. Based on JHK -band photometry and K-band spectroscopy the massive stars are placed in a Hertzsprung Russell diagram. By comparison with evolutionary models, their age and hence the star formation history of W49 can be investigated.
- ID:
- ivo://CDS.VizieR/J/AJ/133/2524
- Title:
- Spectra of young nearby stars
- Short Name:
- J/AJ/133/2524
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present high-dispersion (R~16000) optical (3900-8700{AA}) spectra of 390 stars obtained with the Palomar 60inch telescope. The majority of stars observed are part of the Spitzer Legacy Science Program "The Formation and Evolution of Planetary Systems." Through detailed analysis we determine stellar properties for this sample, including radial and rotational velocities, LiI{lambda}6708 and H{alpha} equivalent widths, the chromospheric activity index R'_HK_, and temperature- and gravity-sensitive line ratios. Several spectroscopic binaries are also identified. From our tabulations, we illustrate basic age- and rotation-related correlations among measured indices. One novel result is that CaII chromospheric emission appears to saturate at vsini values above ~30km/s, similar to the well-established saturation of X-rays that originate in the spatially separate coronal region.
- ID:
- ivo://CDS.VizieR/J/A+A/573/A65
- Title:
- Spectra of young planetary nebulae
- Short Name:
- J/A+A/573/A65
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The evolution of central stars of planetary nebulae was so far documented in just a few cases. However, spectra collected a few decades ago may provide a good reference for studying the evolution of central stars using the emission line fluxes of their nebulae. We investigated evolutionary changes of the [OIII] 5007{AA} line flux in the spectra of planetary nebulae. We compared nebular fluxes collected during a decade or longer. We used literature data and newly obtained spectra. A grid of Cloudy models was computed using existing evolutionary models, and the models were compared with the observations. An increase of the [OIII] 5007{AA} line flux is frequently observed in young planetary nebulae hosting H-rich central stars. The increasing nebular excitation is the response to the increasing temperature and hardening radiation of the central stars. We did not observe any changes in the nebular fluxes in the planetary nebulae hosting late-type Wolf-Rayet (WR) central stars. This may indicate a slower temperature evolution (which may stem from a different evolutionary status) of late-[WR] stars. In young planetary nebulae with H-rich central stars, the evolution can be followed using optical spectra collected during a decade or longer. The observed evolution of H-rich central stars is consistent with the predictions of the evolutionary models provided in the literature. Late-[WR] stars possibly follow a different evolutionary path.
- ID:
- ivo://CDS.VizieR/J/A+A/646/A178
- Title:
- Spectra of 2 z>3 hot dust-obscured galaxies
- Short Name:
- J/A+A/646/A178
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In this paper we present the detection of H_2_O and OH+ emission in z>3 hot dust-obscured galaxies (Hot DOGs). Using ALMA Band-6 observations of two Hot DOGs, we have detected H_2_O(2_02_-1_11_) in W0149+2350, and H_2_O(3_12_-3_03_) and the multiplet OH+(1_1-0_1) in W0410-0913. These detections were serendipitous, falling within the side-bands of Band-6 observations aimed to study CO(9-8) in these Hot DOGs. We find that both sources have luminous H_2_O emission with line luminosities of L_H2O_>2.2x10^8^L_{sun}_ and L_H2O_=8.7x10^8^L_{sun}_ for W0149+2350 and W0410-0913, respectively. The H_2_O line profiles are similar to those seen for the neighbouring CO(9-8) line, with linewidths of FWHM~800-1000km/s. However, the H_2_O emission seems to be more compact than the CO(9-8). OH+ is detected in emission for W0410-0913, with a FWHM=1000km/s and a line luminosity of L_OH+_=6.92x10^8^L_{sun}_. The ratio of the observed H_2_O line luminosity over the IR luminosity, for both Hot DOGs, is consistent with previously observed star forming galaxies and AGN. The H_2_O/CO line ratio of both Hot DOGs and the OH+/H_2_O line ratio of W0410-0913 are comparable to those of luminous AGN in the literature. The bright H_2_O(2_02_-1_11_), and H_2_O(3_12_-3_03_) emission lines are likely due to the combined high star formation levels and luminous AGN in these sources. The presence of OH+ in emission, and the agreement of the observed line ratios of the Hot DOGs with luminous AGN in the literature, would suggest that the AGN emission is dominating the radiative output of these galaxies. However, followup multi-transition observations are needed to better constrain the properties of these systems.
- ID:
- ivo://CDS.VizieR/J/MNRAS/424/1925
- Title:
- Spectrocopic Binarity of O and B type stars
- Short Name:
- J/MNRAS/424/1925
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The formation of stars above about 20M_{sun}_ and their apparently high multiplicity remain heavily debated subjects in astrophysics. We have performed a vast high-resolution radial velocity spectroscopic survey of about 250 O- and 540 B-type stars in the southern Milky Way which indicates that the majority of stars (>82%) with masses above 16M_{sun}_ form close binary systems while this fraction rapidly drops to 20% for stars of 3M_{sun}_. The binary fractions of O-type stars among different environment classes are: clusters (72+/-13%), associations (73+/-8%), field (43+/-13%) and runaways (69+/-11%). The high frequency of close pairs with components of similar mass argues in favour of a multiplicity originating from the formation process rather than from a tidal capture in a dense cluster. The high binary frequency of runaway O stars that we found in our survey (69% compared to 19-26% in previous surveys) points to the importance of ejection from young star clusters and thus supports the competitive accretion scenario.
- ID:
- ivo://CDS.VizieR/J/A+A/433/151
- Title:
- Spectrocopic results on ROSAT late-type stars
- Short Name:
- J/A+A/433/151
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present results of an investigation of the X-ray properties, age distribution, and kinematical characteristics of a high-galactic latitude sample of late-type field stars selected from the ROSAT All-Sky Survey (RASS). The sample comprises 254 RASS sources with optical counterparts of spectral types F to M distributed over six study areas located at |b|>~20{deg}, and Dec>=-9{deg}. A detailed study was carried out for the subsample of ~200 G, K, and M stars. Lithium abundances were determined for 179 G-M stars. Radial velocities were measured for most of the 141 G and K type stars of the sample. Combined with proper motions these data were used to study the age distribution and the kinematical properties of the sample. Based on the lithium abundances half of the G-K stars were found to be younger than the Hyades (660Myr). About 25% are comparable in age to the Pleiades (100Myr). A small subsample of 10 stars is younger than the Pleiades. They are therefore most likely pre-main sequence stars. Kinematically the PMS and Pleiades-type stars appear to form a group with space velocities close to the Castor moving group but clearly distinct from the Local Association.