- ID:
- ivo://CDS.VizieR/J/AJ/152/54
- Title:
- Spectroscopy of main-belt Ch/Cgh-type asteroids
- Short Name:
- J/AJ/152/54
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- CM chondrites are the most common type of hydrated meteorites, making up ~1.5% of all falls. Whereas most CM chondrites experienced only low-temperature (~0{deg}C-120{deg}C) aqueous alteration, the existence of a small fraction of CM chondrites that suffered both hydration and heating complicates our understanding of the early thermal evolution of the CM parent body(ies). Here, we provide new constraints on the collisional and thermal history of CM-like bodies from a comparison between newly acquired spectral measurements of main-belt Ch/Cgh-type asteroids (70 objects) and existing laboratory spectral measurements of CM chondrites. It first appears that the spectral variation observed among CM-like bodies is essentially due to variations in the average regolith grain size. Second, the spectral properties of the vast majority (unheated) of CM chondrites resemble both the surfaces and the interiors of CM-like bodies, implying a "low" temperature (<300{deg}C) thermal evolution of the CM parent body(ies). It follows that an impact origin is the likely explanation for the existence of heated CM chondrites. Finally, similarly to S-type asteroids and (2) Pallas, the surfaces of large (D>100km) - supposedly primordial - Ch/Cgh-type main-belt asteroids likely expose the interiors of the primordial CM parent bodies, a possible consequence of impacts by small asteroids (D<10km) in the early solar system.
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- ID:
- ivo://CDS.VizieR/J/AJ/139/2620
- Title:
- Spectroscopy of M81 globular clusters
- Short Name:
- J/AJ/139/2620
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We obtained spectra of 74 globular clusters (GCs) in M81. These GCs had been identified as candidates in a Hubble Space Telescope (HST) Advanced Camera for Surveys I-band survey. Sixty-eight of these 74 clusters lie within 7' of the M81 nucleus. Sixty-two of these clusters are newly spectroscopically confirmed, more than doubling the number of confirmed M81 GCs from 46 to 108. We determined metallicities for our 74 observed clusters using an empirical calibration based on Milky Way GCs.
2573. Spectroscopy of MWC 297
- ID:
- ivo://CDS.VizieR/J/A+AS/131/479
- Title:
- Spectroscopy of MWC 297
- Short Name:
- J/A+AS/131/479
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- On the basis of spectroscopic CCD material obtained at the Haute Provence Observatory, we provide line identifications and equivalent width measurements in the wavelength region 4100-8900{AA} of the spectrum of MWC 297. About two hundred features are identified, almost exclusively emission lines. Only one interstellar feature could be identified ({lambda}6613) a fact which contrasts with the eigth magnitudes of extinction found by photometrists. The spectrum of the underlying star corresponds probably to a late O or early B-type object. The cooler emission lines correspond to a spectrum of a middle A-type star. Analogies with other stars observed in this series of papers are examined.
2574. Spectroscopy of MWC 645
- ID:
- ivo://CDS.VizieR/J/A+AS/120/99
- Title:
- Spectroscopy of MWC 645
- Short Name:
- J/A+AS/120/99
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We analyse spectroscopic CCD material obtained at the Haute Provence Observatory. We provide identifications and equivalent width measurements in the wavelength region 3740-8790. About 350 emissions lines were measured and about 88 of them were identified. A comparison of our results with those of other authors is provided, as well as a table of elements identified in the spectrum of this star. The pattern of elements present is analogous to that of a late B-type star, but some exceptions are noted, such as the absence of Ne and Mg lines and the presence of K, Cu and Zr lines which appear usually in later type stars. We review the little which is known concerning this object and we also present a quantitative account of the variations in equivalent widths. The observations indicate that the spectrum is highly variable, so that in two different years only half of the lines appear on both spectra. Furthermore variations by at least a factor of two in the equivalent widths are present in many lines. The radial velocity derived from the emission lines (-76km/s) corresponds to that of the shell which probably has a velocity of about 50km/s with respect to the underlying star.
- ID:
- ivo://CDS.VizieR/J/A+AS/118/495
- Title:
- Spectroscopy of MWC 349 A
- Short Name:
- J/A+AS/118/495
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We analyse spectroscopic CCD material obtained at the Haute Provence Observatory. We provide line identifications and equivalent width measurements in the wavelength region 3700-8790A. Over 300 emission features are identified and a comparison of our results with those of other authors is provided, as well as a table of all elements which have been identified in the spectrum of the object. The pattern of elements present is analogous to that of B-type stars, but some exceptions are noted, such as the absence of C, Al and Mn. We review the present knowledge of the spectrum variability of MWC 349A. The observations indicate th at the equivalent widths of the lines of many elements vary by factors of up to two. We also provide a list of diffuse interstellar features observed. The latter lead to an average (B-V) excess of about two magnitudes, which is less than what is expected for an object having an interstellar extinction of 10-11 magnitudes.
- ID:
- ivo://CDS.VizieR/J/A+AS/128/475
- Title:
- Spectroscopy of MWC 158 = HD 50138
- Short Name:
- J/A+AS/128/475
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- On the basis of spectroscopic CCD material obtained at the Haute Provence Observatory, we provide line identifications and equivalent width measurements in the wavelength region 3738-10232 A of the spectrum of HD 50138 Over two hundred features are identified and a comparison of our results with those of other authors is provided. We also discuss the variability of the lines using equivalent widths and descriptions of the line spectrum. We attribute as a best compromise a spectral type of B 5 III. We conclude that the gaseous shell surrounding the star has a temperature of the order of 10 000K and that its distance to the star is of the order of two stellar radii. We discuss the relation of this star to others previously analyzed and warn against hasty generalizations.
- ID:
- ivo://CDS.VizieR/J/AJ/147/20
- Title:
- Spectroscopy of 447 nearby M dwarfs
- Short Name:
- J/AJ/147/20
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present metallicities, radial velocities, and near-infrared (NIR) spectral types for 447 M dwarfs determined from moderate resolution (R{approx}2000) NIR spectra obtained with the NASA Infrared Telescope Facility (IRTF)/SpeX. These M dwarfs are primarily targets of the MEarth Survey, a transiting planet survey searching for super Earths around mid-to-late M dwarfs within 33pc. We present NIR spectral types for each star and new spectral templates for the IRTF in the Y, J, H, and K-bands, created using M dwarfs with near-solar metallicities. We developed two spectroscopic distance calibrations that use NIR spectral type or an index based on the curvature of the K-band continuum. Our distance calibration has a scatter of 14%. We searched 27 NIR spectral lines and 10 spectral indices for metallicity sensitive features, taking into account correlated noise in our estimates of the errors on these parameters. We calibrated our relation using 36 M dwarfs in common proper pairs with an F-, G-, or K-type star of known metallicity. We validated the physical association of these pairs using proper motions, radial velocities, and spectroscopic distance estimates. Our resulting metallicity calibration uses the sodium doublet at 2.2{mu}m as the sole indicator for metallicity. It has an accuracy of 0.12dex inferred from the scatter between the metallicities of the primaries and the estimated metallicities of the secondaries. Our relation is valid for NIR spectral types from M1V to M5V and for -1.0dex<[Fe/H]<+0.35dex. We present a new color-color metallicity relation using J-H and J-K colors that directly relates two observables: the distance from the M dwarf main sequence and equivalent width of the sodium line at 2.2{mu}m. We used radial velocities of M dwarf binaries, observations at different epochs, and comparison between our measurements and precisely measured radial velocities to demonstrate a 4km/s accuracy.
- ID:
- ivo://CDS.VizieR/J/AJ/143/126
- Title:
- Spectroscopy of 462 nearby Type Ia supernovae
- Short Name:
- J/AJ/143/126
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present 2603 spectra of 462 nearby Type Ia supernovae (SNe Ia), including 2065 previously unpublished spectra, obtained during 1993-2008 through the Center for Astrophysics Supernova Program. There are on average eight spectra for each of the 313 SNe Ia with at least two spectra. Most of the spectra were obtained with the FAST spectrograph at the Fred Lawrence Whipple Observatory 1.5m telescope and reduced in a consistent manner, making this data set well suited for studies of SN Ia spectroscopic diversity. Using additional data from the literature, we study the spectroscopic and photometric properties of SNe Ia as a function of spectroscopic class using the classification schemes of Branch et al. (2006PASP..118..560B) and Wang et al. (2009, Cat. J/ApJ/699/L139). The width-luminosity relation appears to be steeper for SNe Ia with broader lines, although the result is not statistically significant with the present sample. Based on the evolution of the characteristic SiII{lambda}6355 line, we propose improved methods for measuring velocity gradients, revealing a larger range than previously suspected, from ~0 to ~400km/s/day considering the instantaneous velocity decline rate at maximum light.
- ID:
- ivo://CDS.VizieR/J/MNRAS/440/2265
- Title:
- Spectroscopy of NGC3310 HII regions
- Short Name:
- J/MNRAS/440/2265
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Numerical simulations of minor mergers predict little enhancement in the global star formation activity. However, it is still unclear the impact they have on the chemical state of the whole galaxy and on the mass build-up in the galaxy bulge and disc. We present a two-dimensional analysis of NCG 3310, currently undergoing an intense starburst likely caused by a recent minor interaction, using data from the PPAK Integral Field Spectroscopy Nearby Galaxies Survey (PINGS). With data from a large sample of about a hundred HII regions identified throughout the disc and spiral arms, we derive, using strong-line metallicity indicators and direct derivations, a rather flat gaseous abundance gradient. Thus, metal mixing processes occurred, as in observed galaxy interactions. Spectra from PINGS data and additional multiwavelength imaging were used to perform a spectral energy distribution fitting to the stellar emission and a photoionization modelling of the nebulae. The ionizing stellar population is characterized by single populations with a narrow age range (2.5-5Myr) and a broad range of masses (10^4^-6x10^6^M_{sun}_). The effect of dust grains in the nebulae is important, indicating that 25-70% of the ultraviolet photons can be absorbed by dust. The ionizing stellar population within the Hii regions represents typically a few per cent of the total stellar mass. This ratio, a proxy to the specific star formation rate, presents a flat or negative radial gradient. Therefore, minor interactions may indeed play an important role in the mass build-up of the bulge.
- ID:
- ivo://CDS.VizieR/J/AJ/123/2828
- Title:
- Spectroscopy of northern NLTT stars
- Short Name:
- J/AJ/123/2828
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present initial results of an all-sky search for late-type dwarfs within 20pc of the Sun using the New Luyten Two-Tenths (NLTT) catalog cross-referenced with the Two Micron All Sky Survey (2MASS) database. The results were obtained with low-resolution optical spectroscopic follow-up of candidate nearby stars as a preliminary test of our methodology. M_J_, derived using spectral indices, and 2MASS J are used to estimate distances. Out of the 70 objects observed, 28 are identified as previously unrecognized objects within 25pc of the Sun, and up to 19 of these are within 20pc. One, LP 647-13, is an M9-type dwarf at 10.5pc, making it one of the four closest M9 dwarfs currently known. We also discuss the chromospheric activity of the observed dwarfs.
