- ID:
- ivo://CDS.VizieR/J/ApJ/721/369
- Title:
- PNe in the elliptical galaxy NGC 821
- Short Name:
- J/ApJ/721/369
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Using a slitless spectroscopy method with the 8.2m Subaru telescope and its FOCAS Cassegrain spectrograph, we have increased the number of planetary nebula (PN) detections and PN velocity measurements in the flattened elliptical galaxy NGC 821. A comparison with the detections reported previously by the Planetary Nebulae Spectrograph group indicates that we have confirmed most of their detections. The velocities measured by the two groups, using different telescopes, spectrographs, and slitless techniques, are in good agreement. We have built a combined sample of 167 PNs and have confirmed the Keplerian decline of the line-of-sight velocity dispersion reported previously. We also confirm misaligned rotation from the combined sample. A dark matter halo may exist around this galaxy, but it is not needed to keep the PN velocities below the local escape velocity as calculated from the visible mass. We have measured the m(5007) magnitudes of 145 PNs and produced a statistically complete sample of 40 PNs in NGC 821. The resulting PN luminosity function (PNLF) was used to estimate a distance modulus of 31.4mag, equivalent to 19Mpc.
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- ID:
- ivo://CDS.VizieR/J/ApJ/736/65
- Title:
- PNe in the Virgo elliptical galaxy NGC 4649
- Short Name:
- J/ApJ/736/65
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Using a slitless spectroscopy method with (1) the 8.2m Subaru telescope and its FOCAS Cassegrain spectrograph and (2) the ESO Very Large Telescope unit 1 (Antu) and its FORS2 Cassegrain spectrograph, we have detected 326 planetary nebulae (PNs) in the giant Virgo elliptical galaxy NGC 4649 (M60) and measured their radial velocities. After rejecting some PNs more likely to belong to the companion galaxy NGC 4647, we have built a catalog with kinematic information for 298 PNs in M60. Using these radial velocities, we have concluded that they support the presence of a dark matter halo around M60. Based on an isotropic, two-component Hernquist model, we estimate the dark matter halo mass within 3R_e_ to be 4x10^11^M_{sun}_, which is almost one-half of the total mass of about 10^12^M_{sun}_ within 3R_e_. This total mass is similar to that estimated from globular cluster, XMM-Newton, and Chandra observations. The dark matter becomes dominant outside. More detailed dynamical modeling of the PN data is being published in a companion paper. We have also measured the m(5007) magnitudes of many of these PNs and built a statistically complete sample of 218 PNs. The resulting PN luminosity function (PNLF) was used to estimate a distance modulus of 30.7+/-0.2mag, equivalent to 14+/-1Mpc. This confirms an earlier PNLF distance measurement based on a much smaller sample. The PNLF distance modulus remains smaller than the surface brightness fluctuation distance modulus by 0.4mag.
- ID:
- ivo://CDS.VizieR/J/A+A/491/951
- Title:
- Positions and cross-references in Coma Ber
- Short Name:
- J/A+A/491/951
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Although several attempts were made to identify solar-type members on the main sequence of the nearby open cluster Coma Berenices (Mel 111), the population of the lower main sequence is still poorly known. We observed 46 new candidates to search for new members and monitored known spectroscopic-binary members to determine orbital parameters. We obtained a total of 903 radial-velocity measurements of 69 solar-type stars in the field of Mel 111 with the CORAVEL spectrovelocimeter over 20 years. Among the 35 stars from Trumpler's list, 23 are members according to their radial velocities and photometry. We were able to confirm the membership of only 8 stars among the 46 candidates observed. Six double-lined and ten single-lined spectroscopic binaries were discovered. Six only are members and an orbit was determined for them and for 4 double-lined non-members. The binary frequency is 22% (7/32). The cluster mean radial velocity is +0.01+/-0.08km/s based on 28 members. The lower main sequence of the Coma Berenices open cluster is still rather poorly populated. The cluster size may be much larger that usually accepted. Accordingly extensive programmes of precise proper motions, radial velocities and photometry should be undertaken to identify faint cluster members outside the cluster central area. If a significant population of faint members cannot be identified, Coma Ber could be a prominent example of dynamical evolution leading to star evaporation.
- ID:
- ivo://CDS.VizieR/J/AJ/126/762
- Title:
- Positions and space velocities for 2615 SGP stars
- Short Name:
- J/AJ/126/762
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Spectrophotometric data have been obtained with the 2dF spectrograph at Cerro Tololo Inter-American Observatory and with Hydra at the WIYN telescope for nearly 2000 A, F, and G stars toward the south Galactic pole. Using 1305 radial velocities, 2311 uvbyH{beta} photometric measurements, and 1621 Yale-San Juan SPM (Southern Proper Motion) absolute proper motions, peculiar velocities were derived to determine the galactic gravitational force K(z) perpendicular to the Galactic plane, first described by Oort (published in 1932).
- ID:
- ivo://CDS.VizieR/J/A+A/513/L7
- Title:
- Post common envelope binaries from SDSS. VIII
- Short Name:
- J/A+A/513/L7
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results of a large survey of post common envelope binaries (PCEBs) among white dwarf/main sequence (WDMS) binaries from the SDSS that allows to determine the fraction of PCEBs as a function of secondary star mass and therewith to ultimately test the disrupted magnetic braking hypothesis. We obtained multiple spectroscopic observations spread over at least two nights of 589 WDMS binaries. Using mostly the NaI 8183.27,8194.81 absorption doublet we determined the corresponding radial velocities.
- ID:
- ivo://CDS.VizieR/J/ApJ/839/92
- Title:
- Praesepe members with K2 light curve data
- Short Name:
- J/ApJ/839/92
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have Fourier-analyzed 941 K2 light curves (LCs) of likely members of Praesepe, measuring periods for 86% and increasing the number of rotation periods (P) by nearly a factor of four. The distribution of P versus (V-Ks), a mass proxy, has three different regimes: (V-Ks)<1.3, where the rotation rate rapidly slows as mass decreases; 1.3<(V-Ks)<4.5, where the rotation rate slows more gradually as mass decreases; and (V-Ks)>4.5, where the rotation rate rapidly increases as mass decreases. In this last regime, there is a bimodal distribution of periods, with few between ~2 and ~10 days. We interpret this to mean that once M stars start to slow down, they do so rapidly. The K2 period-color distribution in Praesepe (~790Myr) is much different than that in the Pleiades (~125Myr) for late F, G, K, and early-M stars; the overall distribution moves to longer periods and is better described by two line segments. For mid-M stars, the relationship has a similarly broad scatter and is steeper in Praesepe. The diversity of LCs and of periodogram types is similar in the two clusters; about a quarter of the periodic stars in both clusters have multiple significant periods. Multi- periodic stars dominate among the higher masses, starting at a bluer color in Praesepe ((V-Ks)~1.5) than in the Pleiades ((V-Ks)~2.6). In Praesepe, there are relatively more LCs that have two widely separated periods, {Delta}P>6days. Some of these could be examples of M star binaries where one star has spun down but the other has not.
- ID:
- ivo://CDS.VizieR/J/AJ/156/142
- Title:
- Precision cluster abund. for APOGEE using SDSS DR14
- Short Name:
- J/AJ/156/142
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Open Cluster Chemical Abundances and Mapping (OCCAM) survey aims to produce a comprehensive, uniform, infrared-based spectroscopic data set for hundreds of open clusters, and to constrain key Galactic dynamical and chemical parameters from this sample. This second contribution from the OCCAM survey presents analysis of 259 member stars with [Fe/H] determinations in 19 open clusters, using Sloan Digital Sky Survey Data Release 14 (SDSS/DR14) data from the Apache Point Observatory Galactic Evolution Experiment and ESA Gaia. This analysis, which includes clusters with R_GC_ ranging from 7 to 13 kpc, measures an [Fe/H] gradient of -0.061+/-0.004 dex/kpc. We also confirm evidence of a significant positive gradient in the {alpha}-elements ([O/Fe], [Mg/Fe], and [Si/Fe]) and present evidence for a significant negative gradient in iron-peak elements ([Mn/Fe] and [Ni/Fe]).
- ID:
- ivo://CDS.VizieR/J/A+A/530/A28
- Title:
- Priority targets for the MUCHFUSS project
- Short Name:
- J/A+A/530/A28
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The project Massive Unseen Companions to Hot Faint Underluminous Stars from SDSS (MUCHFUSS) aims at finding sdBs with compact companions like supermassive white dwarfs (M>1.0M_{sun}_), neutron stars or black holes. The existence of such systems is predicted by binary evolution theory and recent discoveries indicate that they are likely to exist in our Galaxy. A determination of the orbital parameters is sufficient to put a lower limit on the companion mass by calculating the binary mass function. If this lower limit exceeds the Chandrasekhar mass and no sign of a companion is visible in the spectra, the existence of a massive compact companion is proven without the need for any additional assumptions. We identified about 1100 hot subdwarf stars from the SDSS by colour selection and visual inspection of their spectra. Stars with high velocities have been reobserved and individual SDSS spectra have been analysed. In total 127 radial velocity variable subdwarfs have been discovered. Binaries with high RV shifts and binaries with moderate shifts within short timespans have the highest probability of hosting massive compact companions. Atmospheric parameters of 69 hot subdwarfs in these binary systems have been determined by means of a quantitative spectral analysis. The atmospheric parameter distribution of the selected sample does not differ from previously studied samples of hot subdwarfs. The systems are considered the best candidates to search for massive compact companions by follow-up time resolved spectroscopy.
- ID:
- ivo://CDS.VizieR/J/AN/338/686
- Title:
- Pristine survey II. Bright stars abundances
- Short Name:
- J/AN/338/686
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Extremely metal-poor (EMP) stars are old objects formed in the first Gyr of the Universe. They are rare and, to select them the most successful strategy has been to build on large and low-resolution spectroscopic surveys. The combination of narrow- and broad-band photometry provides a powerful and cheaper alternative to select metal-poor stars. The ongoing Pristine Survey is adopting this strategy, conducting photometry with the Canada France Hawaii Telescope MegaCam wide-field imager and a narrow-band filter centered at 395.2nm on the Ca II-H and -K lines. In this paper, we present the results of the spectroscopic follow-up conducted on a sample of 26 stars at the bright end of the magnitude range of the Survey (g<=15), using FEROS at the MPG/ESO 2.2-m telescope (manufactured by Zeiss, Oberkochen, Germany). From our chemical investigation on the sample, we conclude that this magnitude range is too bright to use the Sloan Digital Sky Survey (SDSS) gri bands, which are typically saturated. Instead, the Pristine photometry can be usefully combined with the AAVSO Photometric All Sky Survey (APASS) gri photometry to provide reliable metallicity estimates. Data from FEROS.
- ID:
- ivo://CDS.VizieR/J/AJ/142/71
- Title:
- Proper motions and photometry of stars near NGC7380
- Short Name:
- J/AJ/142/71
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present proper motions, radial velocities, and a photometric study of the Galactic open cluster NGC 7380, which is associated with prominent emission nebulosity and dark molecular clouds. On the basis of the sample of highly probable member stars, the star cluster is found to be at a distance of 2.6+/-0.4kpc, has an age of around 4Myr, and a physical size of ~6pc across with a tidal structure. The binary O-type star DH Cep is a member of the cluster in its late stage of clearing the surrounding material, and may have triggered the ongoing star formation in neighboring molecular clouds which harbor young stars that are coeval and comoving with, but not gravitationally bound by, the star cluster.