- ID:
- ivo://CDS.VizieR/J/ApJ/699/539
- Title:
- Cepheids in SN-Ia host galaxies
- Short Name:
- J/ApJ/699/539
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This is the second of two papers reporting results from a program to determine the Hubble constant to ~5% precision from a refurbished distance ladder based on extensive use of differential measurements. Here we report observations of 240 Cepheid variables obtained with the Near-Infrared Camera and Multi-Object Spectrometer (NICMOS) Camera 2 through the F160W filter on the Hubble Space Telescope (HST). The Cepheids are distributed across six recent hosts of Type Ia supernovae (SNe Ia) and the "maser galaxy" NGC 4258, allowing us to directly calibrate the peak luminosities of the SNe Ia from the precise, geometric distance measurements provided by the masers. New features of our measurement include the use of the same instrument for all Cepheid measurements across the distance ladder and homogeneity of the Cepheid periods and metallicities, thus necessitating only a differential measurement of Cepheid fluxes and reducing the largest systematic uncertainties in the determination of the fiducial SN Ia luminosity. In addition, the NICMOS measurements reduce the effects of differential extinction in the host galaxies by a factor of ~5 over past optical data. Combined with a greatly expanded set of 240 SNe Ia at z<0.1 which define their magnitude-redshift relation, we find H_0_=74.2+/-3.6km/s/Mpc, a 4.8% uncertainty including both statistical and systematic errors.
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- ID:
- ivo://CDS.VizieR/J/A+A/440/487
- Title:
- Cepheids in the young LMC cluster NGC 1866
- Short Name:
- J/A+A/440/487
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present new near-IR light curves for six Cepheids in the young blue LMC cluster NGC 1866 as well as high precision radial velocity curves for ten Cepheids in NGC 1866 and two in NGC 2031. For the six Cepheids in NGC 1866 with new J and K light curves we determine distances and absolute magnitudes by applying the near-IR surface brightness method. We find that the formal error estimates on the derived distances are underestimated by about a factor of two. We find excellent agreement between the absolute magnitudes for the low metallicity LMC Cepheids with the Period-Luminosity (P-L) relation determined by the near-IR surface brightness (ISB) method for Galactic Cepheids suggesting that the slope of the P-L relations for low metallicity and solar metallicity samples could be very similar in contrast to other recent findings. Still there appears to be significant disagreement between the observed slopes of the OGLE based apparent P-L relations in the LMC and the slopes derived from ISB analysis of Galactic Cepheids, and by inference for Magellanic Cloud Cepheids, indicating a possible intrinsic problem with the ISB method itself. Resolving this problem could reaffirm the P-L relation as the prime distance indicator applicable as well to metallicities significantly different from the LMC value.
3273. Cepheids multiphotometry
- ID:
- ivo://CDS.VizieR/J/A+A/383/398
- Title:
- Cepheids multiphotometry
- Short Name:
- J/A+A/383/398
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- New estimates of the distances of 36 nearby galaxies are presented based on accurate distances of galactic Cepheids obtained by Gieren et al. (1998ApJ...496...17G) from the geometrical Barnes-Evans method. The concept of ``sosie'' is applied to extend the distance determination to extragalactic Cepheids without assuming the linearity of the PL relation. Doing so, the distance moduli are obtained in a straightforward way. The correction for extinction is made using two photometric bands (V and I) according to the principles introduced by Freedman & Madore (1990ApJ...365..186F).
- ID:
- ivo://CDS.VizieR/J/AJ/130/1880
- Title:
- Cepheids with periods between 3 and 6 days
- Short Name:
- J/AJ/130/1880
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results of a detailed multiphase spectroscopic analysis of six classical Cepheids with pulsation periods between 3 and 6 days. For each star we have derived phased values of effective temperature, surface gravity, microturbulent velocity, and elemental abundances. We show that the elemental abundance results for these Cepheids are consistent for all pulsational phases.
- ID:
- ivo://nasa.heasarc/cepaxmm
- Title:
- Cepheus A SFR XMM-Newton X-Ray Point Source Catalog
- Short Name:
- CEPAXMM
- Date:
- 02 May 2025
- Publisher:
- NASA/GSFC HEASARC
- Description:
- Cepheus A is a star formation region (SFR) at a distance of ~ 730 pc consisting of two main H II regions, Cep A East and Cep A West. Cep A was observed with the EPIC cameras of the XMM-Newton observatory on 2003 August 23 for 43.9ks. In this observation, X-rays from both components of Cep A, East and West, were discovered by XMM-Newton, as well as from the Herbig-Haro object HH 168, which joins the ranks of other energetic H-H objects that are sources of temperature T >= 10<sup>6</sup> K X-ray emission. A total of 102 distinct X-ray sources were detected in this 44 ks observation, many presumed to be pre-main-sequence stars on the basis of the reddening of their optical and IR counterparts, the latter being found by matching the positions of the 102 X-ray sources with objects in the USNO-B1.0 (Monet et al. 2003, AJ, 125, 984) and Two Micron All Sky Survey (2MASS) catalogs using a 2.5" matching radius. The authors performed source detection on all the XMM-Newton data in two energy bands: 0.2 - 1 keV ("soft") and 1 - 10 keV ("hard"). They detected 24 soft sources and 85 hard sources. Seven of the sources appear in both bands, where the criterion for a match between the bands is a positional offset of < 2.5 arcseconds. Thus, the total number of distinct X-ray sources detected (and listed in this table) is 102. This table was created by the HEASARC in July 2007 based on the <a href="https://cdsarc.cds.unistra.fr/ftp/cats/J/ApJ/626/272">CDS Catalog J/ApJ/626/272</a> file table2.dat. This is a service provided by NASA HEASARC .
- ID:
- ivo://CDS.VizieR/J/A+A/602/A8
- Title:
- Cepheus E CO, OH and OI spectra
- Short Name:
- J/A+A/602/A8
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Protostellar jets and outflows are key features of the star-formation process, and primary processes of the feedback of young stars on the interstellar medium. Understanding the underlying shocks is necessary to explain how jet and outflow systems are launched, and to quantify their chemical and energetic impacts on the surrounding medium. We performed a high-spectral resolution study of the [OI]63um emission in the outflow of the intermediate-mass Class 0 protostar Cep E-mm. The goal is to determine the structure of the outflow, to constrain the chemical conditions in the various components, and to understand the nature of the underlying shocks, thus probing the origin of the mass-loss phenomenon. We present observations of the OI ^3^P_1_ -> ^3^P_2_, OH between ^2^{Pi}_1/2_ J=3/2 and J=1/2 at 1837.8GHz, and CO (16-15) lines with the GREAT receiver onboard SOFIA towards three positions in the Cep E protostellar outflow: Cep E-mm (the driving protostar), Cep E-BI (in the southern lobe), and Cep E-BII (the terminal position in the southern lobe).
- ID:
- ivo://CDS.VizieR/J/ApJS/115/59
- Title:
- Cepheus flare molecular clouds
- Short Name:
- J/ApJS/115/59
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Results of an objective prism Schmidt survey are combined with IRAS survey data in order to assess the star-forming activity in the Cepheus Flare, a nearby giant molecular cloud complex at ~15{deg} above the Galactic equator. The distribution of absorbing matter along the line of sight was also studied. The Wolf diagrams, displaying the cumulative distribution of field star distance moduli, show that the interstellar matter in this region is concentrated at three characteristic distances: 200, 300, and 450pc. The three components, though partly overlapping, can be separated along the Galactic latitude. Within the area of the Cepheus Flare, distances are determined for 14 Lynds dark clouds and for some other clouds.
- ID:
- ivo://CDS.VizieR/J/A+A/573/A19
- Title:
- Cep OB2 Herschel/PACS view
- Short Name:
- J/A+A/573/A19
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The CepOB2 region, with its two intermediate-aged clusters Tr37 and NGC7160, is a paradigm of sequential star formation and an ideal site for studies of protoplanetary disk evolution. We use Herschel data to study the protoplanetary disks and the star formation history of the region. Herschel/PACS observations at 70 and 160{mu}m probe the disk properties (mass, dust sizes, structure) and the evolutionary state of a large number of young stars. Far-IR data also trace the remnant cloud material and small-scale cloud structure. We detect 95 protoplanetary disks at 70{mu}m, 41 at 160{mu}m, and obtain upper limits for more than 130 objects. The detection fraction at 70{mu}m depends on the spectral type (88% for K4 or earlier stars, 17% for M3 or later stars) and on the disk type (~50% for full and pre-transitional disks, ~35% for transitional disks, no low-excess/depleted disks detected). Non-accreting disks are not detected, suggesting significantly lower masses. Accreting transition and pre-transition disks have systematically higher 70{mu}m excesses than full disks, suggestive of more massive, flared and/or thicker disks. Herschel data also reveal several mini-clusters in Tr37, which are small, compact structures containing a few young stars surrounded by nebulosity. Far-IR data are an excellent probe of the evolution of disks that are too faint for sub-millimetre observations. We find a strong link between far-IR emission and accretion, and between the inner and outer disk structure. Herschel confirms the dichotomy between accreting and non-accreting transition disks. Accretion is a powerful measure of global disk evolution: substantial mass depletion and global evolution need to occur to shut down accretion in a protoplanetary disk, even if the disk has inner holes. Disks likely follow different evolutionary paths: low disk masses do not imply opening inner holes, and having inner holes does not require low disk masses. The mini-clusters reveal multi-episodic star formation in Tr37. The long survival of mini-clusters suggest that they formed from the fragmentation of the same core. Their various morphologies favour different formation/triggering mechanisms acting within the same cluster. The beads-on-a-string structure in one mini-cluster is consistent with gravitational fragmentation or gravitational focusing, acting on very small scales (solar-mass stars in ~0.5pc filaments). Multi-episodic star formation could also produce evolutionary variations between disks in the same region. Finally, Herschel also unveils what could be the first heavy mass loss episode of the O6.5 star HD 206267 in Tr 37.
- ID:
- ivo://CDS.VizieR/J/A+AS/134/401
- Title:
- 4C equatorial sample VLA observations. II.
- Short Name:
- J/A+AS/134/401
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- VLA observations at 4.9GHz are given for 144 steep-spectrum 4C sources whose declinations are between -4{deg} and +4{deg} and whose angular sizes are smaller than 30arcsec. The paper contains 150 maps (VLA and 6 MERLIN observations at 1420 or 1658MHz) which are not included here.
- ID:
- ivo://CDS.VizieR/J/MNRAS/443/2815
- Title:
- Cerro Armazones spectroscopy of F dwarfs
- Short Name:
- J/MNRAS/443/2815
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a spectroscopic survey of a sample of F stars that have not yet been searched for planets. The observations of 187 stars obtained with the Bochum Echelle Spectrographic Observer of the Cerro Armazones Observatory were aimed at nearby (closer than 70pc) main-sequence stars without sufficient archive ([fiber-fed extended range optical spectrograph (FEROS)/high accuracy radial velocity planet search (HARPS)]) spectroscopy. The primary goal of the survey was to select the best candidates for radial-velocity searches of extrasolar planets. The spectra were analysed using the broadening-function technique, the method of choice for rapid rotators later than about A5. The analysis was focused not only at the determination of projected rotational velocity (defining precision of radial-velocity determination), but also at the detection of previously unknown spectroscopic binaries/multiples or stars showing strong line asymmetries. 12 previously unknown spectroscopic binaries/triples were detected. For all observed targets the spectral type was determined. About 140 stars are rotating faster than the resolution limit of 10km/s sampling the onset of convection and slow rotation at mid-F spectral types in great detail. Radial-velocity precision of the data (about 100m/s) is insufficient to detect planets but could indicate most SB1 systems with stellar companions. As there are already 2-3 observations per object for these newly detected binary stars, only a few additional follow-up observations will be needed to obtain constraints on orbital parameters. We identified a sample of 68 bright F-type dwarf stars which are perfect targets for future planet searches. They rotate moderately or slowly and do not show any sign of binarity, pulsations, or surface activity.
