- ID:
- ivo://CDS.VizieR/J/AJ/147/16
- Title:
- Spectroscocpy of planetary nebulae in M31
- Short Name:
- J/AJ/147/16
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have developed a method to identify planetary nebula (PN) candidates in imaging data of the Sloan Digital Sky Survey (SDSS). This method exploits the SDSS's five-band sampling of emission lines in PN spectra, which results in a color signature distinct from that of other sources. Selection criteria based on this signature can be applied to nearby galaxies in which PNe appear as point sources. We applied these criteria to the whole area of M31 as scanned by the SDSS, selecting 167 PN candidates that are located in the outer regions of M31. The spectra of 80 selected candidates were then observed with the 2.2m telescope at Calar Alto Observatory. These observations and cross-checks with literature data show that our method has a selection rate efficiency of about 90%, but the efficiency is different for the different groups of PN candidates. In the outer regions of M31, PNe trace different well-known morphological features like the Northern Spur, the NGC 205 Loop, the G1 Clump, etc. In general, the distribution of PNe in the outer region 8<R<20kpc along the minor axis shows the "extended disk"-a rotationally supported low surface brightness structure with an exponential scale length of 3.21+/-0.14kpc and a total mass of ~10^10^M_{sun}_, which is equivalent to the mass of M33. We report the discovery of three PN candidates with projected locations in the center of Andromeda NE, a very low surface brightness giant stellar structure in the outer halo of M31. Two of the PNe were spectroscopically confirmed as genuine PNe. These two PNe are located at projected distances along the major axis of ~48Kpc and ~41Kpc from the center of M31 and are the most distant PNe in M31 found up to now. With the new PN data at hand we see the obvious kinematic connection between the continuation of the Giant Stream and the Northern Spur. We suggest that 20%-30% of the stars in the Northern Spur area may belong to the Giant Stream. In our data we also see a possible kinematic connection between the Giant Stream and PNe in Andromeda NE, suggesting that Andromeda NE could be the core or remnant of the Giant Stream. Using PN data we estimate the total mass of the Giant Stream progenitor to be {approx}10^9^M_{sun}_. About 90% of its stars appear to have been lost during the interaction with M31.
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- ID:
- ivo://CDS.VizieR/J/AJ/151/6
- Title:
- Spectroscopic and photometric properties of Tombaugh 1
- Short Name:
- J/AJ/151/6
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Open clusters can be the key to deepening our knowledge on various issues involving the structure and evolution of the Galactic disk and details of stellar evolution because a cluster's properties are applicable to all its members. However, the number of open clusters with detailed analysis from high-resolution spectroscopy or precision photometry imposes severe limitations on studies of these objects. To expand the number of open clusters with well-defined chemical abundances and fundamental parameters, we investigate the poorly studied, anticenter open cluster Tombaugh 1. Using precision uvbyCaH{beta} photometry and high-resolution spectroscopy, we derive the cluster's reddening, obtain photometric metallicity estimates, and, for the first time, present a detailed abundance analysis of 10 potential cluster stars (nine clump stars and one Cepheid). Using the radial position from the cluster center and multiple color indices, we have isolated a sample of unevolved, probable single-star members of Tombaugh 1. From 51 stars, the cluster reddening is found to be E(b-y)=0.221+/-0.006 or E(B-V)=0.303+/-0.008, where the errors refer to the internal standard errors of the mean. The weighted photometric metallicity from m_1_ and hk is [Fe/H]=-0.10+/-0.02, while a match to the Victoria-Regina Stromgren isochrones leads to an age of 0.95+/-0.10 Gyr and an apparent modulus of (m-M)=13.10+/-0.10. Radial velocities identify six giants as probable cluster members, and the elemental abundances of Fe, Na, Mg, Al, Si, Ca, Ti, Cr, Ni, Y, Ba, Ce, and Nd have been derived for both the cluster and the field stars. Tombaugh 1 appears to be a typical inner thin disk, intermediate-age open cluster of slightly subsolar metallicity, located just beyond the solar circle, with solar elemental abundance ratios except for the heavy s-process elements, which are a factor of two above solar. Its metallicity is consistent with a steep metallicity gradient in the galactocentric region between 9.5 and 12 kpc. Our study also shows that Cepheid XZ CMa is not a member of Tombaugh 1 and reveals that this Cepheid presents signs of barium enrichment, making it a probable binary star.
- ID:
- ivo://CDS.VizieR/J/ApJS/250/26
- Title:
- Spectroscopic follow-up of the QUBRICS quasars
- Short Name:
- J/ApJS/250/26
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results of the spectroscopic follow-up of the QUasars as BRIght beacons for Cosmology in the Southern Hemisphere (QUBRICS; Calderone+ 2019, J/ApJ/887/268) survey. The selection method is based on a machine-learning approach applied to photometric catalogs, covering an area of ~12400deg^2^ in the Southern Hemisphere. The spectroscopic observations started in 2018 and identified 55 new, high-redshift (z>=2.5), bright (i<=18) quasi-stellar objects (QSOs), with the catalog published in late 2019. Here we report the current status of the survey, bringing the total number of bright QSOs at z>=2.5 identified by QUBRICS to 224. The success rate of the QUBRICS selection method, in its most recent training, is estimated to be 68%. The predominant contaminant turns out to be lower-z QSOs at z<2.5. This survey provides a unique sample of bright QSOs at high z available for a number of cosmological investigations. In particular, carrying out the redshift drift measurements (Sandage Test) in the Southern Hemisphere, using the High Resolution Spectrograph at the 39m Extremely Large Telescope appears to be possible with less than 2500hr of observations spread over 30 targets in 25yr.
- ID:
- ivo://CDS.VizieR/J/A+A/622/A110
- Title:
- Spectroscopic membership for NGC 3532
- Short Name:
- J/A+A/622/A110
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- NGC 3532 is an extremely rich open cluster embedded in the Galactic disc, hitherto lacking a comprehensive, documented membership list. We provide membership probabilities from new radial velocity observations of solar-type and low-mass stars in NGC 3532, in part as a prelude to a subsequent study of stellar rotation in the cluster. Using extant optical and infra-red photometry we constructed a preliminary photometric membership catalogue, consisting of 2230 dwarf and turn-off stars. We selected 1060 of these for observation with the AAOmega spectrograph at the 3.9m Anglo-Australian Telescope and 391 stars for observations with the Hydra-South spectrograph at the 4m Victor Blanco Telescope, obtaining spectroscopic observations over a decade for 145 stars. We measured radial velocities for our targets through cross-correlation with model spectra and standard stars, and supplemented them with radial velocities for 433 additional stars from the literature. We also measured logg, Teff, and [Fe/H] from the AAOmega spectra. The radial velocity distribution emerging from the observations is centred at 5.43+/-0.04km/s and has a width (standard deviation) of 1.46km/s. Together with proper motions from Gaia DR2 we find 660 exclusive members, of which five are likely binary members. The members are distributed across the whole cluster sequence, from giant stars to M dwarfs, making NGC~3532 one of the richest Galactic open clusters known to date, on par with the Pleiades. From further spectroscopic analysis of 153 dwarf members we find the metallicity to be marginally sub-solar, with [Fe/H]=-0.07+/-0.10. We confirm the extremely low reddening of the cluster, E_B-V_=0.034+/-0.012mag, despite its location near the Galactic plane. Exploiting trigonometric parallax measurements from Gaia DR2 we find a distance of 484^+35^_-30_pc [(m-M)_0_=8.42+/-0.14mag]. Based on the membership we provide an empirical cluster sequence in multiple photometric passbands. A comparison of the photometry of the measured cluster members with several recent model isochrones enables us to confirm the 300Myr cluster age. However, all of the models evince departures from the cluster sequence in particular regions, especially in the lower mass range.
- ID:
- ivo://CDS.VizieR/J/ApJ/751/46
- Title:
- Spectroscopic observations in VV124 (UGC 4879)
- Short Name:
- J/ApJ/751/46
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- VV124 (UGC 4879) is an isolated, dwarf irregular/dwarf spheroidal (dIrr/dSph) transition-type galaxy at a distance of 1.36 Mpc. Previous low-resolution spectroscopy yielded inconsistent radial velocities for different components of the galaxy, and photometry hinted at the presence of a stellar disk. In order to quantify the stellar dynamics, we observed individual red giants in VV124 with the Keck/Deep Extragalactic Imaging Multi-Object Spectrograph (DEIMOS). We validated members based on their positions in the color-magnitude diagram, radial velocities, and spectral features. Our sample contains 67 members. The average radial velocity is <v_r_>=-29.1+/-1.3km/s in agreement with the previous radio measurements of H I gas. The velocity distribution is Gaussian, indicating that VV124 is supported primarily by velocity dispersion inside a radius of 1.5 kpc. Outside that radius, our measurements provide only an upper limit of 8.6km/s on any rotation in the photometric disk-like feature. The velocity dispersion is {sigma}_v_=9.4+/-1.0km/s, from which we inferred a mass of M_1/2_=(2.1 +/-0.2)x10^7^M_{sun}_ and a mass-to-light ratio of (M/L_V_)_1/2_=5.2+/-1.1M_{sun}_/L_{sun}_, both measured within the half-light radius. Thus, VV124 contains dark matter. We also measured the metallicity distribution from neutral iron lines. The average metallicity, <[Fe/H]>=-1.14+/-0.06, is consistent with the mass-metallicity relation defined by dSph galaxies. The dynamics and metallicity distribution of VV124 appear similar to dSphs of similar stellar mass.
- ID:
- ivo://CDS.VizieR/J/PAZh/27/381
- Title:
- Spectroscopic study of BM Ori
- Short Name:
- J/PAZh/27/381
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Two CCD spectra of the star BM Ori were obtained with the echelle spectrograph of the 6-m telescope. Measured line equivalent widths were used to estimate atmospheric parameters of the secondary star.
- ID:
- ivo://CDS.VizieR/J/AJ/135/1117
- Title:
- Spectroscopic study of red giants in M15
- Short Name:
- J/AJ/135/1117
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- High-resolution spectra of 110 selected red giant stars in the globular cluster M15 (NGC 7078) were obtained with Hectochelle at the MMT telescope in 2005 May, 2006 May, and 2006 October. Echelle orders containing H{alpha} and CaII H&K are used to identify emission and line asymmetries characterizing motions in the extended atmospheres. Emission in H{alpha} is detected to a luminosity of log(L/L_{sun}_)=2.36, in this very metal-deficient cluster, comparable to other studies, suggesting that the appearance of emission wings is independent of stellar metallicity. The faintest stars showing H{alpha} emission appear to lie on the asymptotic giant branch (AGB) in M15. A line-bisector technique for H{alpha} reveals outflowing velocities in all stars brighter than log(L/L_{sun}_)=2.5, and this outflow velocity increases with stellar luminosity, indicating the mass outflow increases smoothly with luminosity. Many stars lying low on the AGB show exceptionally high outflow velocities (up to 10-15km/s) and more velocity variability (up to 6-8km/s) than red giant branch (RGB) stars of similar apparent magnitude. High velocities in M15 may be related to the low cluster metallicity. Dusty stars identified from Spitzer Space Telescope infrared photometry as AGB stars are confirmed as cluster members by radial velocity measurements, yet their H{alpha} profiles are similar to those of RGB stars without dust. If substantial mass loss creates the circumstellar shell responsible for infrared emission, such mass loss must be episodic.
- ID:
- ivo://CDS.VizieR/J/ApJ/834/176
- Title:
- Spectroscopic survey of M37 candidate members
- Short Name:
- J/ApJ/834/176
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results of a spectroscopic survey to characterize chromospheric activity, as measured by H{alpha} emission, in low-mass members of the 500Myr old open cluster M37. Combining our new measurements of H{alpha} luminosities (L_H{alpha}_) with previously cataloged stellar properties, we identify saturated and unsaturated regimes in the dependence of the L_H{alpha}_-to-bolometric luminosity ratio, L_H{alpha}_/L_bol_, on the Rossby number R_o_. All rotators with R_o_ smaller than 0.03+/-0.01 converge to an activity level of L_H{alpha}_/L_bol_=(1.27+/-0.02)x10^-4^. This saturation threshold (R_o,sat_=0.03+/-0.01) is statistically smaller than that found in most studies of the rotation-activity relation. In the unsaturated regime, slower rotators have lower levels of chromospheric activity, with L_H{alpha}_/L_bol_(R_o_) following a power-law of index {beta}=-0.51+/-0.02, slightly shallower than that found for a combined ~650Myr old sample of Hyades and Praesepe stars. By comparing this unsaturated behavior to that previously found for coronal activity in M37 (as measured via the X-ray luminosity, L_X_), we confirm that chromospheric activity decays at a much slower rate than coronal activity with increasing R_o_. While a comparison of L_H{alpha}_ and L_X_ for M37 members with measurements of both reveals a nearly 1:1 relation, removing the mass-dependencies by comparing instead L_H{alpha}_/L_bol_ and L_X_/L_bol_ does not provide clear evidence for such a relation. Finally, we find that R_o,sat_ is smaller for our chromospheric than for our coronal indicator of activity (R_o,sat_=0.03+/-0.01 versus 0.09+/-0.01). We interpret this as possible evidence for coronal stripping.
- ID:
- ivo://CDS.VizieR/J/AJ/130/1871
- Title:
- Spectroscopic survey of M dwarfs
- Short Name:
- J/AJ/130/1871
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have constructed a sample of M dwarfs out to a distance of ~100pc. This sample of 605 stars (574 M dwarfs and 31 K dwarfs) have been spectroscopically observed, yielding spectral types, radial velocities, H{alpha} equivalent widths, and molecular band indices. Photometric observations have been compiled, with photographic plates providing RI magnitudes and JHKs magnitudes from Two Micron All Sky Survey (Cat. <II/246>) observations. Proper motions were determined by a match to USNO-B (Cat. <I/284>), and distances were computed employing a spectroscopic parallax, allowing the computation of UVW space motions.
- ID:
- ivo://CDS.VizieR/J/AJ/143/7
- Title:
- Spectroscopic survey of WISE-selected sources
- Short Name:
- J/AJ/143/7
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report on the results of an optical spectroscopic survey at high Galactic latitude (|b|>=30{deg}) of a sample of WISE-selected targets, grouped by WISE W1 ({lambda}_eff_=3.4{mu}m) flux, which we use to characterize the sources WISE detected. We observed 762 targets in 10 disjoint fields centered on ultraluminous infrared galaxy candidates using DEIMOS on Keck II. We find 0.30+/-0.02 galaxies arcmin^-2^ with a median redshift of z=0.33+/-0.01 for the sample with W1>=120{mu}Jy. The foreground stellar densities in our survey range from 0.23+/-0.07arcmin^-2^ to 1.1+/-0.1arcmin^-2^ for the same sample. We obtained spectra that produced science grade redshifts for >=90% of our targets for sources with W1 flux >=120{mu}Jy that also had an i-band flux >=18{mu}Jy. We used this for targeting very preliminary data reductions available to the team in 2010 August. Our results therefore present a conservative estimate of what is possible to achieve using WISE's Preliminary Data Release for the study of field galaxies.
