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341. Accurate positions of Zwicky galaxies
ID:
ivo://CDS.VizieR/J/A+AS/64/247
Title:
Accurate positions of Zwicky galaxies
Short Name:
J/A+AS/64/247
Date:
21 Oct 2021
Publisher:
CDS
Description:
Accurate optical positions are given for 1007 galaxies in the Zwicky Catalogue fields 502-505, 519-523, 536-539.
342. Accurate SB2 radial velocities
ID:
ivo://CDS.VizieR/J/MNRAS/496/1355
Title:
Accurate SB2 radial velocities
Short Name:
J/MNRAS/496/1355
Date:
21 Oct 2021
Publisher:
CDS
Description:
Double-lined spectroscopic binaries (SB2s) are one of the main sources of stellar masses, as additional observations are only needed to give the inclinations of the orbital planes in order to obtain the individual masses of the components. For this reason, we are observing a selection of SB2s using the SOPHIE spectrograph at the Haute-Provence observatory in order to precisely determine their orbital elements. Our objective is to finally obtain masses with an accuracy of the order of one percent by combining our radial velocity (RV) measurements and the astrometric measurements that will come from the Gaia satellite. We present here the RVs and the re-determined orbits of 10 SB2s. In order to verify the masses we will derive from Gaia, we obtained interferometric measurements of the ESO VLTI for one of these SB2s. Adding the interferometric or speckle measurements already published by us or by others for 4 other stars, we finally obtain the masses of the components of 5 binary stars, with masses ranging from 0.51 to 2.2 solar masses, including main-sequence dwarfs and some more evolved stars whose location in the HR diagram has been estimated.
343. Accurate SB2 radial velocities
ID:
ivo://CDS.VizieR/J/MNRAS/474/731
Title:
Accurate SB2 radial velocities
Short Name:
J/MNRAS/474/731
Date:
21 Oct 2021
Publisher:
CDS
Description:
The orbital motion of non-contact double-lined spectroscopic binaries (SB2s), with periods of a few tens of days to several years, holds unique, accurate information on individual stellar masses, which only long-term monitoring can unlock. The combination of radial velocity measurements from high-resolution spectrographs and astrometric measurements from high-precision interferometers allows the derivation of SB2 component masses down to the percent precision. Since 2010, we have observed a large sample of SB2s with the SOPHIE spectrograph at the Observatoire de Haute-Provence, aiming at the derivation of orbital elements with sufficient accuracy to obtain masses of components with relative errors as low as 1 per cent when the astrometric measurements of the Gaia satellite are taken into account. In this paper, we present the results from 6 yr of observations of 14 SB2 systems with periods ranging from 33 to 4185 days. Using the TODMOR algorithm, we computed radial velocities from the spectra and then derived the orbital elements of these binary systems. The minimum masses of the 28 stellar components are then obtained with an average sample accuracy of 1.0+/-0.2 per cent. Combining the radial velocities with existing interferometric measurements, we derived the masses of the primary and secondary components of HIP 61100, HIP 95995 and HIP 101382 with relative errors for components (A,B) of, respectively, (2.0, 1.7) per cent, (3.7, 3.7) per cent and (0.2, 0.1) per cent. Using the CESAM2K stellar evolution code, we constrained the initial He abundance, age and metallicity for HIP 61100 and HIP 95995.
344. Accurate SB2 radial velocities
ID:
ivo://CDS.VizieR/J/MNRAS/458/3272
Title:
Accurate SB2 radial velocities
Short Name:
J/MNRAS/458/3272
Date:
21 Oct 2021
Publisher:
CDS
Description:
In anticipation of the Gaia astrometric mission, a large sample of spectroscopic binaries has been observed since 2010 with the Spectrographe pour l'Observation des PHenomenes des Interieurs Stellaires et des Exoplanetes spectrograph at the Haute-Provence Observatory. Our aim is to derive the orbital elements of double-lined spectroscopic binaries (SB2s) with an accuracy sufficient to finally obtain the masses of the components with relative errors as small as 1 per cent when the astrometric measurements of Gaia are taken into account. In this paper, we present the results from five years of observations of 10 SB2 systems with periods ranging from 37 to 881d. Using the todmor algorithm, we computed radial velocities from the spectra, and then derived the orbital elements of these binary systems. The minimum masses of the components are then obtained with an accuracy better than 1.2 per cent for the 10 binaries. Combining the radial velocities with existing interferometric measurements, we derived the masses of the primary and secondary components of HIP 87895 with an accuracy of 0.98 and 1.2 per cent, respectively.
345. Accurate water maser positions from HOPS
ID:
ivo://CDS.VizieR/J/MNRAS/442/2240
Title:
Accurate water maser positions from HOPS
Short Name:
J/MNRAS/442/2240
Date:
21 Oct 2021
Publisher:
CDS
Description:
We report on high spatial resolution water maser observations, using the Australia Telescope Compact Array, towards water maser sites previously identified in the H2O southern Galactic Plane Survey (HOPS) within the area covering Galactic coordinates from l=290 to l=30 and b=-0.5 to b=+0.5. Of the 540 maser sites identified in the single-dish observations of Walsh et al. (2011MNRAS.416.1764W, Cat. J/MNRAS/416/1764), we detect emission in all but 31 fields. These maser sites together comprise 2790 individual spectral features (maser spots), with brightnesses ranging from 0.06Jy to 576Jy and with velocities ranging from -238.5 to +300.5km/s. Based on a definition of maser site size of 4-arcsec (except for G000.667+0.028, also known as Sgr B2, which we treat as a special case), we identify 631 maser sites. We have compared the positions of these sites to the literature to associate the sites with astrophysical objects. We identify 433 (69%) with star formation, 121 (19%) with evolved stars and 77 (12%) as unknown. Comparing the properties of maser sites of different origins, we find that those associated with evolved stars tend to have more maser spots and have smaller angular sizes than those associated with star formation. We present evidence that maser sites associated with evolved stars show an increased likelihood of having a velocity range between 15 and 35 km/s compared to other maser sites. We suggest this is because many of these maser sites are associated with the circumstellar shells of the evolved stars, which are expanding at these velocities. Of the 31 non-detections, we conclude they were not detected due to intrinsic variability and confirm previous results showing that such variable masers tend to be weaker and have simpler spectra with fewer peaks. Of the small number of maser sites showing linear features, we find evidence for lines that are both perpendicular and parallel to known outflows, suggesting that in star formation, H_2_O maser origins may be as varied and as complex as those of class II methanol masers.
346. A census of the near-by Psc-Eri stellar stream
ID:
ivo://CDS.VizieR/J/A+A/638/A9
Title:
A census of the near-by Psc-Eri stellar stream
Short Name:
J/A+A/638/A9
Date:
21 Oct 2021
Publisher:
CDS
Description:
Within a sphere of 400pc radius around the Sun, we search for members of the Pisces-Eridanus (Psc-Eri) stellar stream in the Gaia Data Release 2 DR2) data set. We compare basic astrophysical characteristics of the stream with those of the Pleiades. We used a modified convergent-point method to identify stars with 2D - velocities consistent with the space velocity of the Psc-Eri stream and the Pleiades, respectively. We found 1387 members of the Psc-Eri stream in a G-magnitude range from 5.1mag to 19.3mag at distances between 80 and 380pc from the Sun. The stream has a nearly cylindrical shape with a length of at least 700pc and a thickness of 100pc. The accumulated stellar mass of the 1387 members amounts to about 770M_{sun}_, and the stream is gravitationally unbound. For the stream we found an age of about 135Myr. In many astrophysical properties Psc-Eri is comparable to the open cluster M45 (the Pleiades): in its age, its luminosity function (LF), its present-day mass function (PDMF) as well as in its total mass. Nonetheless, the two stellar ensembles are completely unlike in their physical appearance. We cautiously give two possible explanations for this disagreement: (i) the star-formation efficiency in their parental molecular clouds was higher for the Pleiades than for Psc-Eri or/and (ii) the Pleiades had a higher primordial mass segregation immediately after the expulsion of the molecular gas of the parental cloud.
347. AC114 galaxy cluster dynamical analysis
ID:
ivo://CDS.VizieR/J/MNRAS/452/3304
Title:
AC114 galaxy cluster dynamical analysis
Short Name:
J/MNRAS/452/3304
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present a dynamical analysis of the galaxy cluster AC114 based on a catalogue of 524 velocities. Of these, 169 (32 percent) are newly obtained at European Southern Observatory (Chile) with the Very Large Telescope and the VIsible MultiObject spectrograph. Data on individual galaxies are presented and the accuracy of the measured velocities is discussed. Dynamical properties of the cluster are derived. We obtain an improved mean redshift value z=0.31665+/-0.0008 and velocity dispersion {sigma}=1893^+73^_-82_km/s. A large velocity dispersion within the core radius and the shape of the infall pattern suggests that this part of the cluster is in a radial phase of relaxation with a very elongated radial filament spanning 12000km/s. A radial foreground structure is detected within the central 0.5h^-1^Mpc radius, recognizable as a redshift group at the same central redshift value. We analyse the colour distribution for this archetype Butcher-Oemler galaxy cluster and identify the separate red and blue galaxy sequences. The latter subset contains 44 percent of confirmed members of the cluster, reaching magnitudes as faint as R_f_=21.1 (1.0mag fainter than previous studies). We derive a mass M_200_=(4.3+/-0.7)x10^15^M_{sun}_h^-1^. In a subsequent paper, we will utilize the spectral data presented here to explore the mass-metallicity relation for this intermediate redshift cluster.
348. A Chandra X-ray observation of L1251B
ID:
ivo://CDS.VizieR/J/ApJ/694/425
Title:
A Chandra X-ray observation of L1251B
Short Name:
J/ApJ/694/425
Date:
21 Oct 2021
Publisher:
CDS
Description:
I report the results of a 60ks X-ray observation of the L1251 dark cloud in Cepheus, which was acquired with the ACIS-I camera on board the Chandra X-Ray Observatory. Forty-three compact X-ray sources were detected. The field of view was centered on the position of IRAS 22376+7455, an embedded Class 0/I protostar that is closely associated with the bright CO emission core, L1251B-Core E. A very intense impulsive X-ray flare was observed from a location within the formal error ellipse of the IRAS source and in close proximity (within <~1") to a thermal continuum radio source, VLA 3. Given their small spatial offsets, the radio, far-infrared, and X-ray objects appear to be identical and consequently the likely origin and driving source of high-velocity gas flows that are observed in L1251B.
349. ACIS-I observations of NGC 2264
ID:
ivo://CDS.VizieR/J/A+A/455/903
Title:
ACIS-I observations of NGC 2264
Short Name:
J/A+A/455/903
Date:
21 Oct 2021
Publisher:
CDS
Description:
This paper's goal is to improve the member census of the NGC 2264 star-forming region and study the origin of X-ray activity in young PMS stars. We analyze a deep, 100ks long, Chandra ACIS observation covering a 17'x17' field in NGC 2264. The preferential detection in X-rays of low-mass PMS stars gives strong indications of their membership. We study X-ray activity as a function of stellar and circumstellar characteristics by correlating the X-ray luminosities, temperatures, and absorptions with optical and near-infrared data from the literature.
350. Ackermann red stars
ID:
ivo://CDS.VizieR/II/260
Title:
Ackermann red stars
Short Name:
II/260
Date:
21 Oct 2021
Publisher:
CDS
Description:
In the late 1960s Gerhard Ackermann published two lists of extremely red stars (1968ZA.....69..130A and 1970A&A.....8..315A), including what appeared to be reliable spectral classifications for a few hundred stars. The two published papers provide details of the observing and analysis, made between June and October 1968 at the Heidelberg observatory with the 25cm f/3.6 Schmidt camera together with a 10-degree UBK7 prism yielding a dispersion of 3500 {AA}/mm at the atmospheric A band (7700{AA}). Exposures on ammonia-hypersensitized Kodak I-N emulsion + RG665 filter were obtained along with direct plates on I-N emulsion as well as 103a-E + OG550, totalling 101 exposures in all. The spectra were classified by following the precepts of Cameron & Nassau (1955ApJ...122..177C) and Nassau & Velghe (1964ApJ...139..190N). Ackermann initiated photoelectric observations at I and K, but obviously the Heidelberg weather was not conducive to pursuing this. Because the calibration of the photometry on the direct plates was by necessity rather crude, Ackermann's photometric results are not reported here -- the procedures used were sufficient to identify the reddest stars, but not for much else. Approximate V magnitudes were added for all the stars -- for the most part these are merely averages of the photo-blue and -red magnitudes in both GSC-2.2 and USNO-B1.0, but their zero-point and scale should be reliable at the few-tenths magnitude level in this range. Coordinates were drawn from either UCAC2 or 2MASS depending mainly on Declination, since UCAC2 extends only to about +40 Dec in this area. The UCAC2 positions should be good to better than 0.1", and those from 2MASS to 0.2". In a few cases, such as gross overexposure in 2MASS, positions are from various Schmidt survey catalogues, as indicated with each entry. The first 13 stars of the catalog come from the concluding volume of the ZA paper; in the 1970 paper, Ackermann refers to these stars using the acronym HDK, which is adopted here. The published table gave rather rough arcminute-precision positions (for equinox 1965). Star 6 was recovered 1 degree east of the nominal place, and identified with the variable star WX CMi. Along with the positions and IDs, the table shows V magnitudes and the spectral types given in the original paper. Some of the stars are within the region covered by the ASAS-3 survey, so reliable V magnitudes are available along with beautiful lightcurves. Ackermann's second much longer list contains rough photometry from the POSS-I prints for some 400 very red stars in the Cygnus starcloud, and for 254 of these spectral types were also determined. The stars without spectral classifications comprise a diverse group including both red/reddened late-type stars and greatly obscured hotter stars, but no real astrophysical information is given for any of them beyond sheer redness -- these stars are omitted from the catalog. In consultation with Prof Ackermann, the following changes have been made to the spectral types: for stars shown in the original table with a hyphen between two types (e.g. M5-M6), this was to show that the type was uncertain to that degree (i.e. M5 or M6), for which the 'slash' notation of Nancy Houk was preferred, and thus M5-M6 becomes M5/6. One star, 78-0-144, exhibited a range in types, and it is shown as M7-M9. Ackermann also indicated a number of stars as being of very-late type with VO present (separable from the A-band), but where the star was too faint to classify accurately. He agrees these are likely to be in the range M7 to M9, and again these are shown in the slash-style notation as M7/9:, with the colon added to indicate uncertainty since the types were not explicit in the original, and sometimes a question mark for those already marked as uncertain in the original. These changes were made so that machine parsing schemes will be better able to handle the classifications.

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