- ID:
- ivo://CDS.VizieR/J/A+A/652/A56
- Title:
- Hemispheric Sunspot Numbers 1874-2020
- Short Name:
- J/A+A/652/A56
- Date:
- 22 Feb 2022
- Publisher:
- CDS
- Description:
- Previous studies have shown significant North-South asymmetries for various features and indicators of solar activity. These findings suggest some decoupling between the two hemispheres over the solar cycle evolution, supported by dynamo theories. For the most important solar activity index, the sunspot numbers, so far only limited coverage of hemispheric data is available. The aim of this study is to create a continuous series of daily and monthly hemispheric sunspot numbers (HSN) from 1874 until 2020, which will be continuously expanded in the future with the HSN provided by SILSO. Based on the available daily measurements of hemispheric sunspot areas from 1874-2016 from Greenwich Royal Observatory and NOAA, we derive the relative fractions of the Northern and Southern activity. These fractions are applied to the International Sunspot Numbers (ISN) to derive the HSN. This method and obtained data are validated against the HSN available for the period 1945-2004 from Temmer et al. (2006A&A...447..735T, J/A+A/447/735) and 1992 to date by SILSO. Results: We provide a continuous data series and catalogue of daily, monthly mean and 13-month smoothed monthly mean HSN for the time range 1874-2020, i.e. fully covering solar cycles no. 12 to 24, which are consistent with the newly calibrated ISN (Clette et al., 2014SSRv..186...35C). Validation of the reconstructed HSN against the direct data available since 1945 reveals high consistency, with a Pearson correlation coefficients of r=0.94 (0.97) for the daily (monthly mean) data. The cumulative hemispheric asymmetries for cycles 12-24 give a mean value of 16%, with no obvious pattern in North-South predominance over the cycle evolution. The strongest asymmetry occurs for cycle no. 19, in which the Northern hemisphere shows a cumulated predominance of 42%. The phase shift between the peaks of solar activity in the two hemispheres may be up to 28 months, with a mean absolute value over cycles 12-24 of 16.4 months. The phase shifts reveal an overall asymmetry of the Northern hemisphere reaching its cycle maximum earlier (in 10 out of 13 cases), with a mean signed phase shift of -7.6 months. Relating the peak growth rates of the ISN and HSN during the cycle's rise phase, respectively, with the cycle amplitude reveals higher correlations when considering the two hemispheres individually, with r=0.9. Our findings provide further evidence that the evolution of the solar cycle occurs partly independent for the two hemispheres, and demonstrate that empirical solar cycle prediction methods can be improved by investigating the solar cycle dynamics in terms of the hemispheric sunspot number evolution.
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- ID:
- ivo://CDS.VizieR/J/A+A/390/707
- Title:
- Hemispheric Sunspot Numbers 1975-2000
- Short Name:
- J/A+A/390/707
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Hemispheric sunspot numbers including the time span from 1975-2000 are presented. The Sunspot Numbers are calculated from sunspot drawings made at the Kanzelhoehe Solar Observatory (KSO), Austria. The counted northern and southern Sunspot Numbers are normalized and multiplied with the International Sunspot Numbers taken from SIDC for matching days in order to provide the data within an international usage. Days without observation by KSO (about 27 percent) were reconstructed applying a linear interpolation method. As validation of the data, regression methods and a cross-correlation analysis are made with hemispheric Sunspot Numbers from SIDC for the available time span 1992-2000 obtaining very good agreements. The results are given in monthly mean and smoothed monthly mean Sunspot Numbers. Based on this data set an analysis concerning the North-South asymmetry is made in the paper.
- ID:
- ivo://CDS.VizieR/J/A+A/447/735
- Title:
- Hemispheric Sunspot Numbers 1945-2004
- Short Name:
- J/A+A/447/735
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- From sunspot drawings provided by the Kanzelhoehe Solar Observatory, Austria, and the Skalnate Pleso Observatory, Slovak Republic, a data catalogue of hemispheric Sunspot Numbers covering the time span 1945-2004 is extracted. The validated catalogue includes daily, monthly-mean and smoothed-monthly relative sunspot numbers for the northern and southern hemispheres separately and is available for scientific use. Based on this data set an analysis concerning the North-South asymmetry is made within this paper.
- ID:
- ivo://CDS.VizieR/J/A+A/580/A19
- Title:
- Hen 2-155 and Hen 2-161 photometry and spectroscopy
- Short Name:
- J/A+A/580/A19
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a study of Hen 2-155 and Hen 2-161, two planetary nebulae which bear striking morphological similarities to other planetary nebulae known to host close-binary central stars. Both central stars are revealed to be photometric variables while spectroscopic observations confirm that Hen 2-155 is host to a double-eclipsing, post-common-envelope system with an orbital period of 3h 33m making it one of the shortest period binary central stars known. The observations of Hen 2-161 are found to be consistent with a post-common-envelope binary of period ~1-day.
- ID:
- ivo://CDS.VizieR/J/A+A/567/A15
- Title:
- Hen 2-260 emission line fluxes
- Short Name:
- J/A+A/567/A15
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We analysed the planetary nebula Hen 2-260 using optical spectroscopy and photometry. We compared our observations with the literature data in order to search for evolutionary changes. We also searched for photometric variability of the central star. Hen 2-260 was observed with the SAAO 1.0m telescope (photometry) and the SALT telescope (low resolution spectroscopy). We also used archive high resolution Very Large Telescope spectra and Hubble Space Telescope imaging. The nebular line fluxes were modelled with the Cloudy photoionization code in order to derive the stellar and nebular parameters. The planetary nebula shows a complex structure and possibly a bipolar outflow. The nebula is relatively dense and young. The central star is just starting O^+^ ionization (Teff~30000K). Comparison of our observations with literature data indicates a 50% increase of the [OIII] 5007{AA} line flux between 2001 and 2012. We interpret it as the result of the progression of the ionization of O^+^. The central star evolves to higher temperatures at a rate of 45+/-7K/yr. The heating rate is consistent with post-AGB evolutionary tracks for a final mass of 0.626^+0.003^_-0.005_M_{sun}_ or 0.645+/-0.008M_{sun}_ for two different sets of tracks from literature. The photometric monitoring of Hen 2-260 revealed non-periodic variations on a timescale of hours or days. There is no direct indication for central star binarity in the spectrum, nor for a strong stellar wind. The variability may be caused by pulsations of the star. The temperature evolution of the central star can be traced using spectroscopic observations of the surrounding planetary nebula spanning a timescale of roughly a decade. This allows us for precise determination of the stellar mass, since the pace of the temperature evolution depends critically on the core mass. The method is independent on the absolute age of the nebula. The kinematical age of the nebula is consistent with the age obtained from the evolutionary track. The final mass of the central star is close to the peak of the mass distribution for central stars of planetary nebulae found in other studies. The object belongs to a group of young central stars of planetary nebulae showing photometric variability.
- ID:
- ivo://CDS.VizieR/III/135A
- Title:
- Henry Draper Catalogue and Extension
- Short Name:
- III/135A
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- An updated, corrected, and extended machine-readable version of The Henry Draper Catalogue (HD, Cannon & Pickering 1918-1924) is available with documentation from the Astronomical Data Center (ADC) as of April 1989. Published and unpublished errors discovered in the previous version have been corrected; letters indicating supplemental stars in the BD have been moved to a new byte to distinguish them from double-star components; and the machine-readable portion of The Henry Draper Extension (HDE) (HA 100; Cannon 1925-1936) has been converted to the same format as the main catalog with additional data added as necessary. The catalog lists HD numbers, Durchmusterung numbers, positions for equinox B1900, photovisual and photographic magnitudes, spectral types, codes for the intensity of the spectra used, and remarks.
- ID:
- ivo://nasa.heasarc/hdec
- Title:
- Henry Draper Extension Charts Catalog
- Short Name:
- HDEC
- Date:
- 11 Oct 2024
- Publisher:
- NASA/GSFC HEASARC
- Description:
- The Henry Draper (HD) Catalog (Cannon and Pickering 1918 - 1924, Ann. Astron. Obs. Harvard College 91 - 99) and its first extension, the Henry Draper Extension (HDE) Catalog (Cannon 1934, Ann. Astron. Obs. Harvard College 100, 1 - 6), provided spectral classification and rough positions for 272,150 stars and has been widely made use of by the astronomical community for over half a century. A second extension of the HD Catalog, the so-called Henry Draper Extension Charts (HDEC), subsequently extended this spectral classification to fainter magnitudes (Cannon 1937, Ann. Astron. Obs. Harvard College 105, 1; Cannon and Mayall 1949, Ann. Astron. Obs. Harvard College 112), thus adding nearly another 87,000 stars with derived spectral types. The information in the HDEC was published in the form of charts rather than tables like the HD and HDE Catalogs, and consequently has been barely utiized by modern astronomers. In the 1990's, after a pilot project of Roeser et al. (1991, Astr. Ap. Suppl., 88, 277) had demonstrated that it seemed feasible to `revive' the HDEC data, they were converted into a catalog of accurate astrometric parameters along with magnitudes and spectral types by Nesterov et al. (1995, Astr. Ap. Suppl., 110, 367), who used measurements of Cartesian coordinates of stars in the charts and the positions in the Astrographic Catalog (AC) for subsequent cross-identification. The Nesterov et al. (1991) reference should be consulted for the full details on the procedures used to create this HDEC catalog. The HDEC catalog contains information on 86,933 stars, comprising accurate (0.5 arcseconds error) positions, (for more than 96 per cent of them) proper motions with a typical accuracy of 5.5 milliarcseconds (mas) per year, and the original spectral classifications. The current database contains the main portion of the catalog. An additional set of information, primarily comprising HD entries with cross-identifications with known or suspected variable stars, was included in the A.J. Cannon Memorial Volume (Cannon and Mayall 1949). This list was extended by Nesterov et al. (1991) to more than 500 identifications with variable stars. This latter expanded list, together with a list of entries which have uncertain identifications, is not included in the HEASARC version of this catalog, but it is available on the HEASARC website in the directory <a href="/FTP/heasarc/dbase/misc_files/hdec/">/FTP/heasarc/dbase/misc_files/hdec/</a> as the file <a href="/FTP/heasarc/dbase/misc_files/hdec/hdec.remarks">hdec.remarks</a>. If the parameter "remarks" is set to "R" for an entry in the HDEC catalog, this means that there is a remark about that particular star in the above file. This database was created by the HEASARC in April 1998 based on the machine-readable ADC/<a href="https://cdsarc.cds.unistra.fr/ftp/cats/III/182">CDS Catalog III/182</a>. This is a service provided by NASA HEASARC .
- ID:
- ivo://CDS.VizieR/J/MNRAS/493/234
- Title:
- Herbig Ae/Be accretion rates & mechanisms
- Short Name:
- J/MNRAS/493/234
- Date:
- 02 Feb 2022 07:28:24
- Publisher:
- CDS
- Description:
- This work presents a spectroscopic study of 163 Herbig Ae/Be stars. Amongst these, we present new data for 30 objects. Stellar parameters such as temperature, reddening, mass, luminosity, and age are homogeneously determined. Mass accretion rates are determined from H{alpha} emission line measurements. Our data is complemented with the X-Shooter sample from previous studies and we update results using Gaia DR2 parallaxes giving a total of 78 objects with homogeneously determined stellar parameters and mass accretion rates. In addition, mass accretion rates of an additional 85 HAeBes are determined. We confirm previous findings that the mass accretion rate increases as a function of stellar mass, and the existence of a different slope for lower and higher mass stars, respectively. The mass where the slope changes is determined to be 3.98^+1.37_-0.94M_{sun}_. We discuss this break in the context of different modes of disc accretion for low- and high-mass stars. Because of their similarities with T Tauri stars, we identify the accretion mechanism for the late-type Herbig stars with the Magnetospheric Accretion. The possibilities for the earlier-type stars are still open, we suggest the Boundary Layer accretion model may be a viable alternative. Finally, we investigated the mass accretion-age relationship. Even using the superior Gaia based data, it proved hard to select a large enough sub-sample to remove the mass dependence in this relationship. Yet, it would appear that the mass accretion does decline with age as expected from basic theoretical considerations.
- ID:
- ivo://CDS.VizieR/J/A+AS/136/429
- Title:
- Herbig Ae/Be stars candidates
- Short Name:
- J/A+AS/136/429
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have observed 42 Herbig Ae/Be stars candidates in both hemispheres using the high resolution spectrographs AURELIE and ELODIE at OHP, and CES at ESO. Table 1 present the journal of our spectroscopic observations.
- ID:
- ivo://CDS.VizieR/J/AJ/118/1043
- Title:
- Herbig Ae/Be stars catalog
- Short Name:
- J/AJ/118/1043
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- UBVR photometric monitoring of Herbig Ae/Be stars and some related objects has been carried out at Maidanak Observatory in Uzbekistan since 1983. More than 71,000 observations of about 230 stars have been obtained and are made available for anonymous ftp. Virtually all Herbig Ae/Be stars observed are irregular variables (called "UXors" after UX Ori), but there is a wide range of amplitudes from barely detectable to more than 4mag in V. Our data confirm the results of previous studies, which indicate that large-amplitude variability is confined to stars with spectral types later than B8. The distribution of variability ranges is quite similar to what is seen in classical T Tauri stars.