105 research outputs found
New Interstellar Extinction Maps Based on Gaia and Other Sky Surveys
We present new three-dimensional (3D) interstellar extinction maps in the
and Gaia filters within 2 kpc of the Sun, a 3D differential extinction
(dust spatial distribution density) map along the lines of sight in the same
space, a 3D map of variations in the ratio of the extinctions in the and
Gaia filters within 800 pc of the Sun, and a 2D map of total Galactic
extinction through the entire dust half-layer from the Sun to extragalactic
space for Galactic latitudes . The 3D maps have a transverse
resolution from 3.6 to 11.6 pc and a radial resolution of 50 pc. The 2D map has
an angular resolution of 6.1 arcmin. We have produced these maps based on the
Gaia DR3 parallaxes and Gaia, Pan-STARRS1, SkyMapper, 2MASS, and WISE
photometry for nearly 100 million stars. We have paid special attention to the
space within 200 pc of the Sun and high Galactic latitudes as regions where the
extinction estimates have had a large relative uncertainty so far. Our maps
estimate the extinction within the Galactic dust layer from the Sun to an
extended object or through the entire dust half-layer from the Sun to
extragalactic space with a precision mag. This
gives a high relative precision of extinction estimates even at high Galactic
latitudes, where, according to our estimates, the median total Galactic
extinction through the entire dust half-layer from the Sun to extragalactic
objects is mag. We have shown that the presented
maps are among the best ones in data amount, space size, resolution, precision,
and other properties.Comment: 15 pages, 4 table
Kinematics of Tycho-2 Red Giant Clump Stars
Based on the Ogorodnikov-Milne model, we analyze the proper motions of 95 633
red giant clump (RGC) stars from the Tycho-2 Catalogue. The following Oort
constants have been found: A = 15.9+-0.2 km/s/kpc and B = -12.0+-0.2 km/s/kpc.
Using 3632 RGC stars with known proper motions, radial velocities, and
photometric distances, we show that, apart from the star centroid velocity
components relative to the Sun, only the model parameters that describe the
stellar motions in the XY plane differ significantly from zero. We have studied
the contraction (a negative K-effect) of the system of RGC stars as a function
of their heliocentric distance and elevation above the Galactic plane. For a
sample of distant (500--1000 pc) RGC stars located near the Galactic plane
(|Z|<200 pc) with an average distance of d=0.7 kpc, the contraction velocity is
shown to be Kd= -3.5+-0.9 km/s; a noticeable vertex deviation, lxy = 9.1+-0.5
degrees, is also observed for them. For stars located well above the Galactic
plane (|Z|>=200 pc), these effects are less pronounced, Kd = -1.7+-0.5 km/s and
lxy = 4.9+-0.6 degrees. Using RGC stars, we have found a rotation around the
Galactic X axis directed toward the Galactic center with an angular velocity of
-2.5+-0.3 km/s/kpc, which we associate with the warp of the Galactic
stellar-gaseous disk.Comment: 23 pages, 7 figures, 4 table
The Penn State-Torun Centre for Astronomy Planet Search stars. I. Spectroscopic analysis of 348 red giants
We present basic atmospheric parameters (Teff, logg, vt and [Fe/H]) as well
as luminosities, masses, radii and absolute radial velocities for 348 stars,
presumably giants, from the ~1000 star sample observed within the Penn
State-Torun Centre for Astronomy Planet Search with the High Resolution
Spectrograph of the 9.2m Hobby-Eberly Telescope. The stellar parameters are key
ingredients in proper interpretation of newly discovered low-mass companions
while a systematic study of the complete sample will create a basis for future
statistical considerations concerning low-mass companions appearance around
evolved low and intermediate-mass stars. The atmospheric parameters were
derived using a strictly spectroscopic method based on the LTE analysis of
equivalent widths of FeI and FeII lines. With existing photometric data and the
Hipparcos parallaxes we estimated stellar masses and ages via evolutionary
tracks fitting. The stellar radii were calculated from either estimated masses
and the spectroscopic logg or from the spectroscopic Teff and estimated
luminosities. The absolute radial velocities were obtained by cross-correlating
spectra with a numerical template. We completed the spectroscopic analysis for
332 stars of which 327 were found to be giants. For the remaining 16 stars with
incomplete data a simplified analysis was applied. The results show that our
sample is composed of stars with Teff = 4055-6239 K, logg = 1.39-4.78 (5 dwarfs
were identified), logL/Lo = -1.0-3, M = 0.6-3.4 Mo, R = 0.6-52 Ro. The stars in
our sample are generally less metal abundant than the Sun with median [Fe/H] =
-0.15. The estimated uncertainties in the atmospheric parameters were found to
be comparable to those reached in other studies. However, due to lack of
precise parallaxes the stellar luminosities and, in turn, the masses are far
less precise, within 0.2 Mo in best cases, and 0.3 Mo on average.Comment: 31 pages, 19 figures, 10 tables, accepted for publication in A&
Open Clusters IC 4665 and Cr 359 and a Probable Birthplace of the Pulsar PSR B1929+10
Based on the epicyclic approximation, we have simulated the motion of the
young open star clusters IC 4665 and Collinder 359. The separation between the
cluster centers is shown to have been minimal 7 Myr ago, 36 pc. We have
established a close evolutionary connection between IC 4665 and the
Scorpius-Centaurus association -- the separation between the centers of these
structures was pc 15 Myr ago. In addition, the center of IC 4665
at this time was near two well-known regions of coronal gas: the Local Bubble
and the North Polar Spur. The star HIP 86768 is shown to be one of the
candidates for a binary (in the past) with the pulsar PSR B1929+10. At the
model radial velocity of the pulsar km s, a close
encounter of this pair occurs in the vicinity of IC 4665 at a time of -1.1 Myr.
At the same time, using currently available data for the pulsar B1929+10 at its
model radial velocity km s, we show that the hypothesis
of Hoogerwerf et al. (2001) about the breakup of the Oph--B1929+10
binary in the vicinity of Upper Scorpius (US) about 0.9 Myr ago is more
plausible.Comment: 19 pages, 8 figure
GYES, a multifibre spectrograph for the CFHT
We have chosen the name of GYES, one of the mythological giants with one
hundred arms, offspring of Gaia and Uranus, for our instrument study of a
multifibre spectrograph for the prime focus of the Canada-France-Hawaii
Telescope. Such an instrument could provide an excellent ground-based
complement for the Gaia mission and a northern complement to the HERMES project
on the AAT. The CFHT is well known for providing a stable prime focus
environment, with a large field of view, which has hosted several imaging
instruments, but has never hosted a multifibre spectrograph. Building upon the
experience gained at GEPI with FLAMES-Giraffe and X-Shooter, we are
investigating the feasibility of a high multiplex spectrograph (about 500
fibres) over a field of view 1 degree in diameter. We are investigating an
instrument with resolution in the range 15000 to 30000, which should provide
accurate chemical abundances for stars down to 16th magnitude and radial
velocities, accurate to 1 km/s for fainter stars. The study is led by
GEPI-Observatoire de Paris with a contribution from Oxford for the study of the
positioner. The financing for the study comes from INSU CSAA and Observatoire
de Paris. The conceptual study will be delivered to CFHT for review by October
1st 2010.Comment: Contributed talk at the Gaia ELSA conference 2010, S\`evres 7-11 June
2010, to be published on the EAS Series, Editors: C. Turon, F. Arenou & F.
Meynadie
A RAVE investigation on Galactic open clusters I. Radial velocities and metallicities
Context. Galactic open clusters (OCs) mainly belong to the young stellar population in the Milky Way disk, but are there groups and complexes of OCs that possibly define an additional level in hierarchical star formation? Current compilations are too incomplete to address this question, especially regarding radial velocities (RVs) and metallicities ([M/H]).
Aims. Here we provide and discuss newly obtained RV and [M/H] data, which will enable us to reinvestigate potential groupings of open clusters and associations.
Methods. We extracted additional RVs and [M/H] from the RAdial Velocity Experiment (RAVE) via a cross-match with the Catalogue of Stars in Open Cluster Areas (CSOCA). For the identified OCs in RAVE we derived (RV) over bar and ([M/H]) over bar from a cleaned working sample and compared the results with previous findings.
Results. Although our RAVE sample does not show the same accuracy as the entire survey, we were able to derive reliable (RV) over bar for 110 Galactic open clusters. For 37 OCs we publish (RV) over bar for the first time. Moreover, we determined ([M/H]) over bar for 81 open clusters, extending the number of OCs with ([M/H]) over bar by 69
Новые комбинации и названия сосудистых растений Азиатской России.
In this paper, we present nomenclatural novelties required in the course of the preparation of the second, revised version of the checklist of vascular plants of Asian Russia. The first version was published in 2012 (Baikov 2012). At the family level, we accepted the modern classification systems (APG IV for flowering plants, PPG I for lycophytes and ferns, and GPG for gymnosperms). At the genus level, we follow the generic concepts applied for particular taxonomic groups according to the Catalogue of Life (COL; https://www.catalogueoflife.org/), version COL23.5. At the species level, we consistently apply the monotypic species concept (also known in Russia as Komarov’s concept). In total, this paper presents one new nothogenus name (× Sibirotrisetokoeleria Chepinoga nom. nov., Poaceae) and 156 new names in the rank of species, in 28 families: Amaranthaceae Juss. (1 name), Amaryllidaceae J. St.-Hil. (1), Apiaceae Lindl. (2), Asteraceae Bercht. & J.Presl (12), Boraginaceae Juss. (4), Caryophyllaceae Juss. (11), Crassulaceae J. St.-Hill. (3), Cyperaceae Juss. (8), Ericaceae Juss. (2), Fabaceae Lindl. (16), Gentianaceae Juss. (1), Geraniaceae Juss. (1), Juncaceae Juss. (1), Lamiaceae Martinov (1), Menyanthaceae Dumort. (1), Orchidaceae Juss. (1), Orobanchaceae Vent. (1), Papaveraceae Juss. (4), Plantaginaceae Juss. (1), Poaceae Barnhart (49), Polygonaceae Juss. (4), Primulaceae Batsch. ex Borkh. (6), Ranunculaceae Juss. (4), Rosaceae Juss. (5), Salicaceae Mirb. (2), Saxifragaceae Juss. (11), Vitaceae Juss. (1), Zygophyllaceae R. Br. (2 names)
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