First results from a large-scale proper motion study of the Galactic centre

Proper motion studies of stars in the centre of the Milky Way have typically been limited to the Arches and Quintuplet clusters, and to the central parsec. Here we present the first results of a large-scale proper motion study of stars within several tens of parsecs of Sagittarius A* based on our 0.2″ angular resolution GALACTICNUCLEUS survey (epoch 2015) combined with NICMOS/HST data from the Paschen-α survey (epoch 2008). This comprises the first extensive proper motion study of the central ∼36′×16′ of the Galaxy, which is not covered adequately by any of the existing astronomical surveys, such as Gaia, because of the extreme interstellar extinction (AV ≳ 30 mag). Proper motions can help us to disentangle the different stellar populations along the line-of-sight and interpret their properties in combination with multi-wavelength photometry from GALACTICNUCLEUS and other sources. It also allows us to infer the dynamics and interrelationships between different stellar components (Galactic bulge, nuclear stellar disk, nuclear stellar cluster) of the Galactic centre (GC). In particular, we use proper motions to detect co-moving groups of stars which are able to trace low-mass or partially-dissolved young clusters in the GC that can hardly be discovered by any other means. Our pilot study for this work is based on a field in the nuclear bulge associated with HII regions that show the presence of young stars. We have detected the first group of co-moving stars coincident with an H II region. Using colour–magnitude diagrams, we have inferred that the co-moving stars are consistent with the post-main sequence stars with ages of few Myr. Simulations show that this group of stars is a real group that can indicate the existence of a dissolving or low-to-intermediate-mass young cluster. A census of these undiscovered clusters will ultimately help us to constrain star formation at the GC in the past few ten Myr.

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A Proper Motion Study of the Pleiades Cluster

Symposium - International Astronomical Union ◽

10.1017/s0074180900147710 ◽

1985 ◽

Vol 113 ◽

pp. 477-480

Author(s):

Floor van Leeuwen

Keyword(s):

Central Region ◽

Proper Motion ◽

Proper Motions ◽

Motion Study ◽

First Results ◽

Image Position

The first results of an extensive proper motion study of the Pleiades cluster are presented. A total of 166 exposures covering a 3 by 3 degrees area are now incorporated. The accuracies of the centennial proper motions range from in the central region to in the outermost region.

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Proper motions in the Galactic bulge: Plaut's window

Proceedings of the International Astronomical Union ◽

10.1017/s1743921308018097 ◽

2007 ◽

Vol 3 (S245) ◽

pp. 351-354

Author(s):

Katherine Vieira ◽

Dana Cassetti-Dinescu ◽

René A. Méndez ◽

R. Michael Rich ◽

Terrence M. Girard ◽

...

Keyword(s):

Proper Motion ◽

Galactic Rotation ◽

Red Giants ◽

Proper Motions ◽

Motion Study ◽

Solar Motion ◽

Two Samples ◽

Red Clump ◽

Good Agreement ◽

Peak Value

AbstractA proper motion study of a field of 20′ × 20′ inside Plaut's low extinction window (l,b)=(0o, −8o), has been completed. Relative proper motions and photographicBVphotometry have been derived for ~ 21,000 stars reaching toV~ 20.5 mag, based on the astrometric reduction of 43 photographic plates, spanning over 21 years of epoch difference. Proper motion errors are typically 1 mas yr−1. Cross-referencing with the 2MASS catalog yielded a sample of ~ 8700 stars, from which predominantly disk and bulge subsamples were selected photometrically from theJHcolor-magnitude diagram. The two samples exhibited different proper-motion distributions, with the disk displaying the expected reflex solar motion. Galactic rotation was also detected for stars between ~2 and ~3 kpc from us. The bulge sample, represented by red giants, has an intrinsic proper motion dispersion of (σl, σb) = (3.39, 2.91)±(0.11, 0.09) mas yr−1, which is in good agreement with previous results. A mean distance of$6.37^{+0.87}_{-0.77}$kpc has been estimated for the bulge sample, based on the observedKmagnitude of the horizontal branch red clump. The metallicity [M/H] distribution was also obtained for a subsample of 60 bulge giants stars, based on calibrated photometric indices. The observed [M/H] shows a peak value at [M/H] ~ −0.1 with an extended metal poor tail and around 30% of the stars with supersolar metallicity. No change in proper motion dispersion was observed as a function of [M/H]. We are currently in the process of obtaining CCDUBV RIphotometry for the entire proper-motion sample of ~ 21,000 stars.

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Proper motion measurements for stars up to 100 kpc with Subaru HSC and SDSS Stripe 82

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/staa3975 ◽

2020 ◽

Author(s):

Tian Qiu ◽

Wenting Wang ◽

Masahiro Takada ◽

Naoki Yasuda ◽

Željko Ivezić ◽

...

Keyword(s):

Proper Motion ◽

Tangential Velocity ◽

Space Structures ◽

Galactic Centre ◽

Proper Motions ◽

Distance Range ◽

Common Reference ◽

Motion Display ◽

Motion Measurements ◽

Set Up

Abstract We present proper motion measurements for more than 0.55 million main-sequence stars, by comparing astrometric positions of matched stars between the multi-band imaging datasets from the Hyper Suprime-Cam (HSC) Survey and the SDSS Stripe 82. In doing this we use 3 million galaxies to recalibrate the astrometry and set up a common reference frame between the two catalogues. The exquisite depth and the nearly 12 years of time baseline between HSC and SDSS enable high-precision measurements of statistical proper motions for stars down to i ≃ 24. A validation of our method is demonstrated by the agreement with the Gaia proper motions, to the precision better than 0.1 mas yr−1. To retain the precision, we make a correction of the subtle effects due to the differential chromatic refraction in the SDSS images based on the comparison with the Gaia proper motions against colour of stars, which is validated using the SDSS spectroscopic quasars. Combining with the photometric distance estimates for individual stars based on the precise HSC photometry, we show a significant detection of the net proper motions for stars in each bin of distance out to 100 kpc. The two-component tangential velocities after subtracting the apparent motions due to our own motion display rich phase-space structures including a clear signature of the Sagittarius stream in the halo region of distance range [10,35] kpc. We also measure the tangential velocity dispersion in the distance range 5–20 kpc and find that the data are consistent with a constant isotropic dispersion of 80 ± 10 km/s. More distant stars appear to have random motions with respect to the Galactic centre on average.

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The Y dwarf population with HST: unlocking the secrets of our coolest neighbours – I. Overview and first astrometric results

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/staa3732 ◽

2020 ◽

Vol 501 (1) ◽

pp. 911-915

Author(s):

C Fontanive ◽

L R Bedin ◽

D C Bardalez Gagliuffi

Keyword(s):

Proper Motion ◽

Hubble Space Telescope ◽

Proper Motions ◽

Brown Dwarf ◽

Space Telescope ◽

First Results

ABSTRACT In this paper, we present our project that aims at determining accurate distances and proper motions for the Y brown dwarf population using the Hubble Space Telescope. We validate the program with our first results, using a single new epoch of observations of the Y0pec dwarf WISE J163940.83−684738.6. These new data allowed us to refine its proper motion and improve the accuracy of its parallax by a factor of three compared to previous determinations, now constrained to ϖ = 211.11 ± 0.56 mas. This newly derived absolute parallax corresponds to a distance of 4.737 ± 0.013 pc, an exquisite and unprecedented precision for faint ultracool Y dwarfs.

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Determining Motions and Birthplaces of Pulsars through VLBI Astrometry

International Astronomical Union Colloquium ◽

10.1017/s025292110004608x ◽

1998 ◽

Vol 164 ◽

pp. 391-392

Author(s):

T. J. Galama ◽

J. Van Paradijs ◽

E. P. J. van den Heuvel ◽

A. G. de Bruyn ◽

R. M. Campbell ◽

...

Keyword(s):

Flux Density ◽

Proper Motion ◽

Mass Range ◽

Solar Neighborhood ◽

Proper Motions ◽

First Results ◽

Motion Measurements

AbstractWe present first results of global VLBI astrometric pulsar parallax and proper motion measurements (phase-reference). The aim is to obtain information on pulsar motions and pulsar birthplaces. Proper motions could provide answers to questions like: How large are pulsar velocities at birth? How are these velocities produced and what is the final galactic pulsar distribution? Identification of birthplaces (with, e.g., an OB-association) provides information on the pulsar progenitor population (the fraction of pulsars born in binaries; the mass range of the progenitors etc.). We have a first epoch on three pulsars, selected on the basis of age (young < 3 Myr), flux density (relatively strong) and presence in the solar neighborhood (d < 3 kpc). Gating increases the SNR by typically a factor of 5.

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Solar Motion And Galactic Rotation: Results From The Lick Northern Proper Motion Program

Symposium - International Astronomical Union ◽

10.1017/s0074180900139956 ◽

1988 ◽

Vol 133 ◽

pp. 427-432

Author(s):

Robert B. Hanson

Keyword(s):

Proper Motion ◽

Rotation Curve ◽

Zero Point ◽

Galactic Rotation ◽

Proper Motions ◽

Circular Velocity ◽

Solar Motion ◽

First Results ◽

Galactic Rotation Curve ◽

Detailed Presentation

This paper reports the first results of solar motion and galactic rotation studies which are being done at Lick Observatory, using the new data from the Lick Northern Proper Motion (NPM) Program. This study finds: (1) A = +11.31 ± 1.06 and B = −13.91 ± 0.92 km/s/kpc, consistent with a nearly flat galactic rotation curve with a local circular velocity near 200 km/s; (2) solar apex locations lying near the standard apex for low galactic latitudes, but trending strongly toward the direction of galactic rotation for high galactic latitudes; (3) RMS external error estimates for the Lick proper motions: for the absolute zero-point in a typical NPM field, and for the overall systematic zero-point error. A more detailed presentation of these results has been given by Hanson (1987). The NPM program is reviewed in another paper in this Symposium, and has been described in detail by Klemola, Jones, and Hanson (1987).

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The Fingerprint of a Galactic Nucleus

Proceedings of the International Astronomical Union ◽

10.1017/s1743921316011959 ◽

2016 ◽

Vol 11 (S322) ◽

pp. 257-258

Author(s):

Francisco Nogueras-Lara ◽

Rainer Schödel

Keyword(s):

Large Scale ◽

Near Infrared ◽

Angular Resolution ◽

Galactic Center ◽

Fold Increase ◽

Galactic Centre ◽

High Angular Resolution ◽

Imaging Data ◽

First Results ◽

Multi Wavelength

AbstractBecause of the unique observational challenges -extreme crowding and extinction- any existing large-scale near-infrared (NIR) imaging data on the Galactic Center (GC) are limited by either one, or a combination, of the following: saturation, lack of sensitivity, too low angular resolution, or lack of multi-wavelength coverage. To overcome this situation, we are currently carrying out a sensitive, 0.2” resolution JHK imaging survey of the Galactic Centre with HAWK-I/VLT. Thanks to holographic imaging, we achieve a similar resolution than with HST/WFC, but can cover also the long NIR, beyond 2 micrometers, which is essential to deal with extinction. Our survey is supported by an ESO Large Programme and will provide photometrically accurate (few percent uncertainty for H < 18 stars), high-angular resolution, NIR data for an area of several 1000 pc2, a more than ten-fold increase compared to the current state of affairs. Here we present an overview and first results.

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GaiaNIR – A future all-sky astrometry mission

Proceedings of the International Astronomical Union ◽

10.1017/s1743921317005348 ◽

2017 ◽

Vol 12 (S330) ◽

pp. 67-70

Author(s):

David Hobbs ◽

Erik Høg

Keyword(s):

Interstellar Extinction ◽

Galactic Centre ◽

Proper Motions ◽

New Era ◽

New Science ◽

Technical Issues ◽

Optical Wavelengths ◽

Space Astrometry ◽

Opening Up ◽

Spiral Arm

AbstractWith the launch of Gaia in December 2013, Europe entered a new era of space astrometry following in the footsteps of the very successful Hipparcos mission. A weakness of Gaia is that it only operates at optical wavelengths. However, much of the Galactic centre and the spiral arm regions are obscured by interstellar extinction. An obvious improvement on Gaia is to include the Near-Infra-Red (NIR) which requires the use of new types of detectors. Additionally, to scan the entire sky and measure global absolute parallaxes the spacecraft must have a constant rotation resulting in a moving image that must be compensated for by, for example, operating the detectors in Time Delayed Integration (TDI) mode. If these technical issues can be solved a new Gaia-like mission separated by a 20 year interval would give; 1) NIR all-sky astrometry and photometry to penetrate the obscured regions and to observe intrinsically red objects with almost diffraction limited resolution; 2) improved proper motions with fourteen times smaller errors than from Gaia alone opening up new science cases, such as long period exoplanets and accurate halo measurements; 3) allow the slowly degrading accuracy of the Gaia reference frame, which will be the basis for future astronomical measurements, to be reset.

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New ultracool dwarf neighbours within 20 pc from Gaia DR2

Astronomy and Astrophysics ◽

10.1051/0004-6361/201937373 ◽

2020 ◽

Vol 637 ◽

pp. A45

Author(s):

R.-D. Scholz

Keyword(s):

Proper Motion ◽

Visual Inspection ◽

Near Infrared ◽

Galactic Plane ◽

Proper Motions ◽

Magnitude Diagram ◽

Motion Measurements ◽

Moving Groups ◽

Absolute Magnitudes ◽

Gaia Dr2

Aims. The Gaia data release 2 (DR2) contains > 6000 objects with parallaxes (Plx + 3 × e_Plx) > 50 mas, placing them within 20 pc from the Sun. Because the expected numbers based on extrapolating the well-known 10 pc census are much lower, nearby Gaia stars need a quality assessment. The 20 pc sample of white dwarfs (WDs) has been verified and completed with Gaia DR2. We here confirm and complete the 20 pc sample of ultracool dwarfs (UCDs) with spectral types ≳M7 and given Gaia DR2 parallaxes. Methods. Dividing the Gaia DR2 20 pc sample into subsamples of various astrometric and photometric quality, we studied their distribution on the sky, in the MG versus G − RP colour-magnitude diagram (CMD), and as a function of G magnitude and total proper motion. After excluding 139 known WDs and 263 known UCDs from the CMD, we checked all remaining ≈3500 candidates with MG > 14 mag (used to define UCDs in this study) for the correctness of their Gaia DR2 proper motions by visual inspection of finder charts, comparison with proper motion catalogues, and comparison with our own proper motion measurements. For confirmed UCD candidates we estimated spectral types photometrically using Gaia and near-infrared absolute magnitudes and colours. Results. We failed to confirm new WDs, but found 50 new UCD candidates that are not mentioned in three previous studies using Gaia DR2. They have relatively small proper motions and low tangential velocities and are concentrated towards the Galactic plane. Half of them have spectral types in SIMBAD and/or previous non-Gaia distance estimates that placed them already within 20 pc. For 20 of the 50 objects, we estimated photometric spectral types of M6−M6.5, slightly below the classical UCD spectral type limit. However, seven L4.5−L6.5, four L0−L1, five M8.5−M9.5, and three M7−M8 dwarfs can be considered as completely new UCDs discoveries within 20 pc based on Gaia DR2. Four M6.5 and two L4.5 dwarfs have high membership probabilities (64%−99%) in the ARGUS, AB Doradus, or Carina Near young moving groups.

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The substructure of the Perseus star-forming region: a survey with Gaia DR2

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/stab352 ◽

2021 ◽

Vol 503 (3) ◽

pp. 3232-3242

Author(s):

Tatiana Pavlidou ◽

Aleks Scholz ◽

Paula S Teixeira

Keyword(s):

Proper Motion ◽

Motion Parallax ◽

Young Stars ◽

Galactic Latitude ◽

Proper Motions ◽

Kinematic Data ◽

Star Forming ◽

Moving Groups ◽

Cold Dust ◽

Gaia Dr2

ABSTRACT We use photometric and kinematic data from Gaia DR2 to explore the structure of the star-forming region associated with the molecular cloud of Perseus. Apart from the two well-known clusters, IC 348 and NGC 1333, we present five new clustered groups of young stars, which contain between 30 and 300 members, named Autochthe, Alcaeus, Heleus, Electryon, and Mestor. We demonstrate that these are co-moving groups of young stars, based on how the candidate members are distributed in position, proper motion, parallax, and colour–magnitude space. By comparing their colour–magnitude diagrams to isochrones, we show that they have ages between 1 and 5 Myr. Using 2MASS and WISE colours, we find that the fraction of stars with discs in each group ranges from 10 to ∼50 per cent. The youngest of the new groups is also associated with a reservoir of cold dust, according to the Planck map at 353 GHz. We compare the ages and proper motions of the five new groups to those of IC 348 and NGC 1333. Autochthe is clearly linked with NGC 1333 and may have formed in the same star formation event. The seven groups separate roughly into two sets that share proper motion, parallax, and age: Heleus, Electryon, and Mestor as the older set, and NGC 1333 and Autochthe as the younger set. Alcaeus is kinematically related to the younger set, but at a more advanced age, while the properties of IC 348 overlap with both sets. All older groups in this star-forming region are located at higher galactic latitude.

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