- ID:
- ivo://CDS.VizieR/J/AJ/107/1556
- Title:
- Late B-type stars classification
- Short Name:
- J/AJ/107/1556
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In the fourth and final of a series of papers on the late B to the early F type stars, we refine the MK spectral classification system for the late B type stars and consider the effect of rotation on both spectral classification and Stromgren photometry of these stars. We extend the work of Morgan by establishing self-consistent sequences of narrow and broadlined standards. We reclassify a number of Bp stars, compare these classifications with Stromgren photometry and consider the question of whether all Bp stars are main-sequence objects.
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Search Results
- ID:
- ivo://CDS.VizieR/J/PASP/111/1169
- Title:
- Late-type stars toward galactic antirotation
- Short Name:
- J/PASP/111/1169
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Low-resolution objective-prism spectra (1360{AA}/mm at H{gamma}) of 184 late-type stars in the Galactic antirotation direction have been obtained with the Curtis Schmidt telescope at Cerro Tololo Inter-American Observatory. The stars have been classified into three groups: F6-G2, G3-K0, and K1-M8. Subsequent observations on the BV and DDO systems have been obtained. The correlation between the thin-prism classes and the DDO classes is as expected, with no significant systematic differences of note. A comparison of Guide Star Catalog magnitudes, corrected to V, is also made, with favorable results. The stars in this list are expected to be useful for studying the structure and star formation history of the Milky Way.
- ID:
- ivo://CDS.VizieR/J/A+AS/24/35
- Title:
- LMC A-F supergiants
- Short Name:
- J/A+AS/24/35
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A survey for A-F type supergiants in the Large Magellanic Cloud has been carried out using UV objective prism plates. 890 objects were detected and their spectral types, luminosity classes, magnitudes, and precise positions determined. The survey is practically complete to m_pg_=12.5 and extends for certain types of stars to m_pg_=14. It is found that the spatial distribution of the A-F supergiants is not correlated with the distribution of the gas and OB stars of the cloud. This is evidence in support of the tentative identification by Stock and Wroblewski of early-type galactic supergiants well off the plane. Several other implications of this result are also discussed.
- ID:
- ivo://CDS.VizieR/III/230
- Title:
- Magnitudes and spectral types in 5 galactic fields
- Short Name:
- III/230
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This catalog was initially compiled at the Abastumani Observatory, containing photographic BV magnitudes and spectral classes for about 6000 stars up to V(lim)=13.0mag in five circular areas of 18{deg}^2^ located near the galactic-equator plane; the observations were made with the Abastumani 70cm Maksutov plus 4{deg} and 8{deg} prisms, yielding dispersions of 166 and 666 {AA}/mm at H-{gamma}. The compilation did not provide the star positions, and the magnitudes were found to have a rms scatter around 0.15mag, i.e. around 0.2mag for the B-V color index. The charts were compared with the GSC1.1 (Cat. I/220) by B. Skiff (Lowell Observatory) thus providing accurate coordinates; B. Skiff also examined the cross-identifications with several other catalogues, and added the notes.
- ID:
- ivo://CDS.VizieR/J/MNRAS/418/2219
- Title:
- Main sequence intrinsic colours: O8V to M0V
- Short Name:
- J/MNRAS/418/2219
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A new Monte Carlo method has been developed in order to derive ages of young embedded clusters in massive star-forming regions where there is strong differential reddening. After foreground and infrared excess source candidates are removed, each cluster candidate star is individually dereddened. Simulated clusters are constructed using isochrones, an initial mass function, realistic photometric errors, simulated background field populations and extinction distributions. These synthetic clusters are then dereddened in the same way as the real data, obtained from a deep near-infrared survey, and used to derive the ages of three embedded clusters. Results were found to be consistent with those determined using spectrophotometric methods. This new method provides way to determine the ages of embedded clusters when only photometric data are available and there is strong differential reddening.
- ID:
- ivo://CDS.VizieR/J/A+A/626/A50
- Title:
- Massive stars in NGC 346
- Short Name:
- J/A+A/626/A50
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Spectroscopy for 247 stars towards the young cluster NGC 346 in the Small Magellanic Cloud has been combined with that for 116 targets from the VLT-FLAMES Survey of Massive Stars. Spectral classification yields a sample of 47 O-type and 287 B-type spectra, while radial-velocity variations and/or spectral multiplicity have been used to identify 45 candidate single-lined (SB1) systems, 17 double-lined (SB2) systems, and one triple-lined (SB3) system. Atmospheric parameters (T_eff_ and log g) and projected rotational velocities (v_e_sini) have been estimated usingTLUSTY model atmospheres; independent estimates of v_e_sini were also obtained using a Fourier Transform method. Luminosities have been inferred from stellar apparent magnitudes and used in conjunction with the T_eff_ and v_e_sini estimates to constrain stellar masses and ages using theBONNSAI package. We find that targets towards the inner region of NGC 346 have higher median masses and projected rotational velocities, together with smaller median ages than the rest of the sample. There appears to be a population of very young targets with ages of less than 2Myr, which have presumably all formed within the cluster. The more massive targets are found to have lower projected rotational velocities consistent with previous studies. No significant evidence is found for differences with metallicity in the stellar rotational velocities of early-type stars, although the targets in the Small Magellanic Cloud may rotate faster than those in young Galactic clusters. The rotational velocity distribution for single non-supergiant B-type stars is inferred and implies that a significant number have low rotational velocity (~=10% with v_e_<40km/s), together with a peak in the probability distribution at v_e_~=300km/s. Larger projected rotational velocity estimates have been found for our Be-type sample and imply that most have rotational velocities between 200-450km/s.
- ID:
- ivo://CDS.VizieR/J/A+A/640/A40
- Title:
- 1002 mCP stars from LAMOST DR4
- Short Name:
- J/A+A/640/A40
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The present work is aimed at identifying new mCP stars using spectra collected by the Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST). Suitable candidates were selected by searching LAMOST DR4 spectra for the presence of the characteristic 5200{AA} flux depression. Spectral classification was carried out with a modified version of the MKCLASS code and the accuracy of the classifications was estimated by comparison with results from manual classification and the literature. Using parallax data and photometry from Gaia DR2, we investigated the space distribution of our sample stars and their properties in the colour-magnitude diagram. Our final sample consists of 1002 mCP stars, most of which are new discoveries (only 59 common entries with the Catalogue of Ap, HgMn and Am stars). Traditional mCP star peculiarities have been identified in all but 36 stars, highlighting the efficiency of the code's peculiarity identification capabilities. The derived temperature and peculiarity types are in agreement with manually derived classifications and the literature. Our sample stars are between 100Myr and 1Gyr old, with the majority having masses between 2M_{sun}_ and 3M_{sun}_. Our results could be considered as strong evidence for an inhomogeneous age distribution among low-mass (M<3M_{sun}_) mCP stars; however, we caution that our sample has not been selected on the basis of an unbiased, direct detection of a magnetic field. We identified several astrophysically interesting objects: the mCP stars LAMOST J122746.05+113635.3 and LAMOST J150331.87+093125.4 have distances and kinematical properties in agreement with halo stars; LAMOST J034306.74+495240.7 is an eclipsing binary system (Porb=5.1435+/-0.0012d) hosting an mCP star component; and LAMOST J050146.85+383500.8 was found to be an SB2 system likely comprising of an mCP star and a supergiant component. With our work, we significantly increase the sample size of known Galactic mCP stars, paving the way for future in-depth statistical studies.
- ID:
- ivo://CDS.VizieR/J/MNRAS/466/1290
- Title:
- Metal-rich SX Phe stars in Kepler field
- Short Name:
- J/MNRAS/466/1290
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A spectroscopic and photometric analysis has been carried out for 32 candidate SX Phe variable blue straggler stars in the Kepler field. Radial velocities (RVs), space motions (U, V, W), projected rotation velocities (vsini), spectral types and atmospheric characteristics (T_eff_, logg, [Fe/H], {xi}_t_, {zeta}_RT_, etc.) are presented for 30 of the 32 stars. Although several stars are metal-weak with extreme halo orbits, the mean [Fe/H] of the sample is near-solar, thus the stars are more metal-rich than expected for a typical sample of Pop. II stars and more like halo metal-rich A-type stars. Two-thirds of the stars are fast rotators with vsini>50km/s^, including four stars with vsini>200km/s. Three of the stars have (negative) RVs>250km/s^, five have retrograde space motions and 21 have total speeds (relative to the Local Standard of Rest) >400km/s. All but one of the 30 stars have positions in a Toomre diagram consistent with the kinematics of bona fide halo stars (the exception being a thick-disc star). Observed Romer time delays, pulsation frequency modulations and light curves suggest that at least one-third of the stars are in binary (or triple) systems with orbital periods ranging from 2.3d to more than four years.
- ID:
- ivo://CDS.VizieR/J/PASJ/33/107
- Title:
- M giants in Cassiopeia
- Short Name:
- J/PASJ/33/107
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Coordinates and identifications for M-type stars in Cassiopeia
- ID:
- ivo://CDS.VizieR/J/other/RAA/15.1154
- Title:
- M-giant star candidates in LAMOST DR 1
- Short Name:
- J/other/RAA/15.1
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We perform a discrimination procedure with the spectral index diagram of TiO_5_ and CaH_2_+CaH_3_ to separate M giants from M dwarfs. Using the M giant spectra identified from LAMOST DR1 with high signal-to-noise ratio, we have successfully assembled a set of M giant templates, which show more reliable spectral features. Combining with the M dwarf/subdwarf templates in Zhong et al. (2015AJ....150...42Z, Cat. J/AJ/150/42), we present an extended library of M-type templates which includes not only M dwarfs with a well-defined temperature and metallicity grid but also M giants with subtypes from M0 to M6. Then, the template-fitting algorithm is used to automatically identify and classify M giant stars from LAMOST DR1. The resulting catalog of M giant stars is cross-matched with 2MASS JHKs and WISE W1/W2 infrared photometry. In addition, we calculated the heliocentric radial velocity of all M giant stars by using the cross-correlation method with the template spectrum in a zero-velocity rest frame. Using the relationship between the absolute infrared magnitude MJ and our classified spectroscopic subtype, we derived the spectroscopic distance of M giants with uncertainties of about 40%. A catalog of 8639 M giants is provided. As an additional result of this analysis, we also present a catalog of 101690 M dwarfs/subdwarfs which are processed by our classification pipeline.
