- ID:
- ivo://CDS.VizieR/J/MNRAS/357/1337
- Title:
- H{alpha} survey of cluster galaxies
- Short Name:
- J/MNRAS/357/1337
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have extended our H{alpha} objective prism survey of eight low-redshift clusters (viz. Abell 262, 347, 400, 426, 569, 779, 1367 and 1656) to include a complete sample of early-type galaxies within 1.5 Abell radii of the cluster centres. Of the 379 galaxies surveyed, 3 per cent of E, E-S0 galaxies, 6 per cent of S0 galaxies, and 9 per cent of S0/a galaxies were detected in emission. From a comparison of cluster and supercluster field galaxies, we conclude that the frequency of emission-line galaxies (ELGs; W>=20{AA}) is similar for field and cluster early-type galaxies. A similar result has previously been obtained for galaxies of types Sa and later. Together, these results confirm the inference of Biviano et al. (1997A&A...321...84B) that the relative frequency of ELGs in clusters and the field can be entirely accounted for by the different mix of morphological types between the differing environments, and that, for galaxies of a given morphological type, the fraction of ELGs is independent of environment. Detected emission is classified as 'compact' or 'diffuse', identified as circumnuclear starburst or active galactic nucleus (AGN) emission and disc emission, respectively. By comparing spectroscopic data for cluster early-type ELGs with data for field galaxies from the Palomar spectroscopic survey of nearby galactic nuclei, we demonstrate that there is modest evidence for an enhancement of compact H II emission relative to AGN emission in the early-type cluster ELGs as compared to the field. For the cluster early-type galaxies, compact H II emission correlates strongly with a disturbed morphology. This suggests that, as for later-type cluster galaxies, this enhanced compact H II emission can readily be explained as an enhancement of circumnuclear starburst emission due to gravitational tidal interactions, most likely caused by subcluster merging and other on-going processes of cluster virialization.
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Search Results
- ID:
- ivo://CDS.VizieR/J/ApJS/199/36
- Title:
- H{alpha} survey of nearby clusters of galaxies
- Short Name:
- J/ApJS/199/36
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results of a wide-field H{alpha} imaging survey of eight nearby (z=0.02-0.03) Abell clusters. We have measured H{alpha} fluxes and equivalent widths for 465 galaxies, of which 360 are new detections. The survey was designed to obtain complete emission-line-selected inventories of star-forming galaxies in the inner regions of these clusters, extending to star formation rates below 0.1M_{sun}_/yr. This paper describes the observations, data processing, and source identification procedures, and presents an H{alpha} and R-band catalog of detected cluster members and other candidates. Future papers in the series will use these data to study the completeness of spectroscopically based star formation surveys, and to quantify the effects of cluster environment on the present-day populations of star-forming galaxies. The data will also provide a valuable foundation for imaging surveys of redshifted H{alpha} emission in more distant clusters.
- ID:
- ivo://CDS.VizieR/J/MNRAS/435/707
- Title:
- H{alpha} velocity curves of IM Eri
- Short Name:
- J/MNRAS/435/707
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report photometric detections of orbital and superorbital signals, and negative orbital sidebands, in the light curves of the nova-like cataclysmic variables AQ Mensae and IM Eridani. The frequencies of the orbital, superorbital and sideband signals are 7.0686 (3), 0.263 (3) and 7.332 (3) cycles/d (c/d) in AQ Mensae, and 6.870 (1), 0.354 (7) and 7.226 (1) c/d in IM Eridani. We also find a spectroscopic orbital frequency in IM Eridani of 6.86649 (2) c/d. These observations can be reproduced by invoking an accretion disc that is tilted with respect to the orbital plane. This model works well for X-ray binaries, in which irradiation by a primary neutron star can account for the disc's tilt. A likely tilt mechanism has yet to be identified in CVs, yet the growing collection of observational evidence indicates that the phenomenon of tilt is indeed at work in this class of object. The results presented in this paper bring the number of CVs known to display signals associated with retrograde disc precession to 12. We also find AQ Men to be an eclipsing system. The eclipse depths are highly variable, which suggests that the eclipses are grazing. This finding raises the possibility of probing variations in disc tilt by studying systematic variations in the eclipse profile.
- ID:
- ivo://CDS.VizieR/J/ApJ/778/56
- Title:
- Hamburg/ESO Survey extremely metal-poor stars
- Short Name:
- J/ApJ/778/56
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- From detailed abundance analysis of >100 Hamburg/ESO candidate extremely metal-poor (EMP) stars we find 45 with [Fe/H]<-3.0dex. We identify a heretofore unidentified group: Ca-deficient stars with sub-solar [Ca/Fe] ratios and the lowest neutron-capture abundances; the Ca-deficient group comprises ~10% of the sample, excluding Carbon stars. Our radial velocity distribution shows that the carbon-enhanced stars with no s-process enhancements, CEMP-no, and which do not show C_2_ bands are not preferentially binary systems. Ignoring Carbon stars, approximately 15% of our sample are strong (>=5{sigma}) outliers in one or more elements between Mg and Ni; this rises to ~19% if very strong (>=10{sigma}) outliers for Sr and Ba are included. Examples include: HE0305-0554 with the lowest [Ba/H] known; HE1012-1540 and HE2323-0256, two (non-velocity variable) C-rich stars with very strong [Mg,Al/Fe] enhancements; and HE1226-1149, an extremely r-process rich star.
- ID:
- ivo://CDS.VizieR/J/A+AS/137/299
- Title:
- Hamburg/SAO Survey for ELGs. II.
- Short Name:
- J/A+AS/137/299
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the second part of the Hamburg/SAO Survey for Emission-Line Galaxies (HSS therein, SAO - Special Astrophysical Observatory, Russia) which is based on the digitized objective-prism photoplates database of the Hamburg Quasar Survey (HQS). The main goal of the project is the search for emission-line galaxies (ELG) in order to create a new deep sample of blue compact/HII galaxies (BCG) in a large sky area. Another important goal of this work is to search for new extremely low-metallicity galaxies. In this paper we present new results of spectroscopy obtained with the 6m Russian telescope. The main ELG candidate selection criteria applied are blue or flat enough continuum (near 4000A) and the presence of strong or moderate emission lines close to 5000A recognized on digitized prism spectra of galaxies with the survey estimated B-magnitudes in the range 16 - 19.5. No other criteria were applied. The spectroscopy resulted in detection and quantitative spectral classification of 134 emission-line objects. For 121 of them the redshifts are determined for the first time. For 13 ELGs known before emission line ratios are presented at first time. 108 of 134 emission-line objects are classified as BCG/HII galaxies and 6 probable BCGs, 6 as QSOs, 1 as Seyfert galaxy, 1 as super-association in a dwarf spiral galaxy, 2 as probable LINERs, 14 are low excitation objects - either of starburst nuclei (SBN), or dwarf amorphous nuclei starburst galaxy (DANS) type -, and 1 nonclassified. 23 galaxies did not show significant emission lines. The five most metal-deficient BCGs discovered have oxygen abundances log(O/H)+12 in the range 7.4 to 7.7, similar to the most metal-deficient BCGs known before.
- ID:
- ivo://CDS.VizieR/J/A+AS/142/417
- Title:
- Hamburg/SAO Survey for ELGs. III.
- Short Name:
- J/A+AS/142/417
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the third list with results of the Hamburg/SAO Survey for Emission-Line Galaxies (HSS therein, SAO - Special Astrophysical Observatory, Russia). This survey is based on the digitized objective-prism photoplate database of the Hamburg Quasar Survey (HQS). Here, we present new spectroscopic results of candidates which were obtained in 1998 with the 2.1m KPNO and the 2.2m Calar Alto telescopes. All candidates are selected in the declination band +35{deg} to +40{deg}. The follow-up spectroscopy with the 2m class telescopes confirmed 85 emission-line objects out of 113 observed candidates and allowed their quantitative spectral classification. For 80 of them, the redshifts are determined for the first time. For 5 previously known Emission-Line Galaxies (ELGs), line ratios are presented for the first time. We could classify 55 out of the 85 emission-line objects as BCG/HII galaxies or probable BCGs (Blue Compact Galaxies) , 4 - as QSOs, 6 - as Seyfert galaxies, 1 - as super-association in a subluminous spiral galaxy, and 11 are low-excitation objects - either starburst nuclei (SBN), or dwarf amorphous nuclei starburst galaxies (DANS). We could not classify 8 ELGs. Further, for 8 more galaxies we did not detect any significant emission lines.
- ID:
- ivo://CDS.VizieR/J/ApJ/792/L31
- Title:
- HARPS and HARPS-N 55 Cnc radial velocities
- Short Name:
- J/ApJ/792/L31
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present Rossiter-McLaughlin observations of the transiting super-Earth 55 Cnc e collected during six transit events between 2012 January and 2013 November with HARPS and HARPS-N. We detect no radial velocity signal above 35 cm/s (3{sigma}) and confine the stellar vsini_*_ to 0.2+/-0.5 km/s. The star appears to be a very slow rotator, producing a very low amplitude Rossiter-McLaughlin effect. Given such a low amplitude, the Rossiter-McLaughlin effect of 55 Cnc e is undetected in our data, and any spin-orbit angle of the system remains possible. We also performed Doppler tomography and reach a similar conclusion. Our results offer a glimpse of the capacity of future instrumentation to study low amplitude Rossiter-McLaughlin effects produced by super-Earths.
- ID:
- ivo://CDS.VizieR/J/AJ/160/129
- Title:
- HARPS, HIRES and AAT Radial Velocities of HD 136352
- Short Name:
- J/AJ/160/129
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Some of the most scientifically valuable transiting planets are those that were already known from radial velocity (RV) surveys. This is primarily because their orbits are well characterized and they preferentially orbit bright stars that are the targets of RV surveys. The Transiting Exoplanet Survey Satellite (TESS) provides an opportunity to survey most of the known exoplanet systems in a systematic fashion to detect possible transits of their planets. HD136352 (Nu Lupi) is a naked-eye (V=5.78) G-type main-sequence star that was discovered to host three planets with orbital periods of 11.6, 27.6, and 108.1days via RV monitoring with the High Accuracy Radial velocity Planet Searcher (HARPS) spectrograph. We present the detection and characterization of transits for the two inner planets of the HD136352 system, revealing radii of 1.482_-0.056_^+0.058^ R{Earth} and 2.608_-0.077_^+0.078^ R{Earth} for planets b and c, respectively. We combine new HARPS observations with RV data from the Keck/High Resolution Echelle Spectrometer and the Anglo-Australian Telescope, along with TESS photometry from Sector 12, to perform a complete analysis of the system parameters. The combined data analysis results in extracted bulk density values of {rho}_b_=7.8_-1.1_^+1.2^g/cm3 and {rho}_c_=3.50_-0.36_^+0.41^g/cm3 for planets b and c, respectively, thus placing them on either side of the radius valley. The combination of the multitransiting planet system, the bright host star, and the diversity of planetary interiors and atmospheres means this will likely become a cornerstone system for atmospheric and orbital characterization of small worlds.
- ID:
- ivo://CDS.VizieR/J/AJ/155/107
- Title:
- HARPS-N observations of K2-141 planetary system
- Short Name:
- J/AJ/155/107
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Ultra-short period (USP) planets are a class of low-mass planets with periods shorter than one day. Their origin is still unknown, with photo-evaporation of mini-Neptunes and in situ formation being the most credited hypotheses. Formation scenarios differ radically in the predicted composition of USP planets, and it is therefore extremely important to increase the still limited sample of USP planets with precise and accurate mass and density measurements. We report here the characterization of a USP planet with a period of 0.28 days around K2-141 (EPIC 246393474), and the validation of an outer planet with a period of 7.7 days in a grazing transit configuration. We derived the radii of the planets from the K2 light curve and used high-precision radial velocities gathered with the HARPS-N spectrograph for mass measurements. For K2-141b, we thus inferred a radius of 1.51+/-0.05 R_{Earth}_ and a mass of 5.08+/-0.41 M_{Earth}_, consistent with a rocky composition and lack of a thick atmosphere. K2-141c is likely a Neptune-like planet, although due to the grazing transits and the non-detection in the RV data set, we were not able to put a strong constraint on its density. We also report the detection of secondary eclipses and phase curve variations for K2-141b. The phase variation can be modeled either by a planet with a geometric albedo of 0.30+/-0.06 in the Kepler bandpass, or by thermal emission from the surface of the planet at ~3000 K. Only follow-up observations at longer wavelengths will allow us to distinguish between these two scenarios.
- ID:
- ivo://CDS.VizieR/J/AJ/152/204
- Title:
- HARPS-N radial velocities of HD 179070
- Short Name:
- J/AJ/152/204
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- HD 179070, aka Kepler-21, is a V=8.25 F6IV star and the brightest exoplanet host discovered by Kepler. An early detailed analysis by Howell et al. of the first 13 months (Q0-Q5) of Kepler light curves revealed transits of a planetary companion, Kepler-21b, with a radius of about 1.60+/-0.04R_{Earth}_ and an orbital period of about 2.7857days. However, they could not determine the mass of the planet from the initial radial velocity (RV) observations with Keck-HIRES, and were only able to impose a 2{sigma} upper limit of 10M_{Earth}_. Here, we present results from the analysis of 82 new RV observations of this system obtained with HARPS-N, together with the existing 14 HIRES data points. We detect the Doppler signal of Kepler-21b with a RV semiamplitude K=2.00+/-0.65ms^-1^, which corresponds to a planetary mass of 5.1+/-1.7M_{Earth}_. We also measure an improved radius for the planet of 1.639 +0.019/-0.015R_{Earth}_, in agreement with the radius reported by Howell et al. We conclude that Kepler-21b, with a density of 6.4+/-2.1gcm^-3^, belongs to the population of small, <~6M_{Earth}_ planets with iron and magnesium silicate interiors, which have lost the majority of their envelope volatiles via stellar winds or gravitational escape. The RV analysis presented in this paper serves as an example of the type of analysis that will be necessary to confirm the masses of TESS small planet candidates.
