- ID:
- ivo://CDS.VizieR/J/ApJ/899/166
- Title:
- Disturbance storm time index of 1903 sun outburst
- Short Name:
- J/ApJ/899/166
- Date:
- 14 Mar 2022 09:07:00
- Publisher:
- CDS
- Description:
- This paper presents the results of the spectrum analysis of the B-type magnetic chemically peculiar star HR465. HR465 shows unusual abundance patterns that vary with a period of 21.5yr. Our observations are recorded at ph=0.45, 0.68, and 0.85 of the spectroscopic period, where ph=0 represents the phase of maximum flux in the photometric y-band. Synthetic spectra, computed using an LTE atmosphere model, are fit to high-resolution ultraviolet Hubble Space Telescope (ph=0.45) spectra obtained as part of the Advanced Spectral Library Project: Hot Stars program. The ultraviolet data are supplemented by high-resolution optical spectra (ph=0.68 and 0.85) recorded at the Nordic Optical Telescope with the SOFIN spectrograph. The optical data are used as a complement to the high line-density ultraviolet spectrum to derive accurate abundances for elements without spectral lines in the ultraviolet and to improve the abundance phase coverage for many atoms/ions. This analysis presents abundance results for more than 70 atoms/ions and confirms parts of the abundance characteristics previously reported where elements with high mass numbers show significant abundance enhancements compared with solar values while some of the lighter elements show abundance deficiencies. In addition, our measured abundances are consistent with the periodic variability for chromium and rare-earth elements. Our results are compared with earlier investigations of this peculiar object to constrain stellar abundance and diffusion.
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- ID:
- ivo://CDS.VizieR/J/A+A/420/673
- Title:
- Elemental abundances of CP2 star HR 5049
- Short Name:
- J/A+A/420/673
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A spectrum synthesis analysis for photospheric lines in the magnetic B star HR 5049 is presented, based on a high quality spectrogram obtained with the EMMI spectrograph attached to the NTT at ESO. It is found that light elements such as He, C and O are under-abundant. One of the most notable features is the deficiency of He by more than -2.0dex. Co and Cl are over-abundant by +3.5dex and +1.9dex, respectively. Other iron peak elements are over-abundant ranging from +0.47dex (Ti II) to +1.94 dex (Cr I). For rare earth elements, the lines of once-ionized species are generally weak, while the third spectra (especially those of Pr and Nd) are very prominent. Although rare earth elements show significant over-abundances ranging from +3.0dex to as large as +4.0dex, Ba has the solar abundance. The Nd-Pr abundance difference, which shows an apparent decreasing trend with increasing effective temperature among CP stars, is found to be unusually small in HR 5049.
- ID:
- ivo://CDS.VizieR/J/MNRAS/475/5144
- Title:
- Magnetic early B-type stars. I.
- Short Name:
- J/MNRAS/475/5144
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The rotational and magnetic properties of many magnetic hot stars are poorly characterized, therefore the MiMeS and BinaMIcS collaborations have collected extensive high-dispersion spectropolarimetric datasets of these targets. We present longitudinal magnetic field measurements <B_Z_> for 52 early B-type stars (B5 to B0), with which we attempt to determine their rotational periods Prot. Supplemented with high-resolution spectroscopy, low-resolution DAO circular spectropolarimetry, and archival Hipparcos photometry, we determined Prot for 10 stars, leaving only 5 stars for which Prot could not be determined. Rotational ephemerides for 14 stars were refined via comparison of new to historical magnetic measurements. The distribution of Prot is very similar to that observed for the cooler Ap/Bp stars. We also measured vsini and v_mac_ for all stars. Comparison to non-magnetic stars shows that vsini is much lower for magnetic stars, an expected consequence of magnetic braking. We also find evidence that v_mac_ is lower for magnetic stars. LSD profiles extracted using single-element masks revealed widespread, systematic discrepancies in <B_Z_> between different elements: this effect is apparent only for chemically peculiar stars, suggesting it is a consequence of chemical spots. Sinusoidal fits to H line <B_Z_> measurements (which should be minimally affected by chemical spots), yielded evidence of surface magnetic fields more complex than simple dipoles in 6 stars for which this has not previously been reported; however, in all 6 cases the second- and third-order amplitudes are small relative to the first-order (dipolar) amplitudes.
- ID:
- ivo://CDS.VizieR/J/A+A/425/263
- Title:
- Spectroscopic atlas of HD175640
- Short Name:
- J/A+A/425/263
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a high resolution spectral atlas of the HgMn star HD 175640 covering the 3040-10000{AA} region. UVES spectra observed with 90000-110000 resolving power and signal to noise ratio ranging from 200 to 400 are compared with a synthetic spectrum computed with the SYNTHE code (Kurucz, 1993, CD-ROM, No. 18). The model atmosphere is an ATLAS12 model (Kurucz, 1997, in The 3rd Conf. on Faint Blue Stars, ed. Philip, Liebert & Saffer (Schenectady: L. Davis Press), 33) with parameters Teff=12000K,logg=3.95, vturb=0km/s. The stellar individual abundances in ATLAS12 were derived from an iterative procedure. The starting atomic line lists downloaded from the Kurucz website have been improved and extended by examining different sources in the literature and by comparing the computed profiles with the observed spectrum. The high quality of the data allowed us to study the isotopic and hyperfine structure for several lines of Mn II, Ga II, Ba II, Pt II, Hg I, and Hg II. Numerous weak emission lines from Cr II and Ti II have been identified in the red part of the spectrum, starting at about 5847{AA}. Two emission lines of C I (mult. 10, mult. 9) have been observed for the first time. All Cr II and Ti II emission lines originate from the high excitation states (Elow>89000cm^-1^ for Cr II and Elow>62000cm^-1^ for Ti II) with large transition probabilities (loggf>-1.00). The synthetic spectrum superimposed on the observed spectrum are available at http://wwwuser.oat.ts.astro.it/castelli/stars.html . An extended discussion on each identified ion and related atomic data is available both in the quoted website and in an electronic Appendix to the paper.
