Interstellar Extinction Law in theJ,H, andKsBands toward the Galactic Center

Nishiyama, Shogo; Nagata, T.; Kusakabe, Nobuhiko; Matsunaga, Noriyuki; Naoi, Takahiro; Kato, Daisuke; Nagashima, Chie; Sugitani, Koji; Tamura, Motohide; Tanabé, Toshihiko; Sato, Shuji

doi:10.1086/499038

Cited by 244 publications

(422 citation statements)

References 27 publications

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“…We used photometry from the SIRIUS catalogue (Nishiyama et al 2006) for eight stars, and for three further bright stars without HAWK-I, NACO or SIRIUS photometry, we used photometry form the 2MASS catalogue (Skrutskie et al 2006). For almost 1000 stars we have the JHK S photometry from either NACO/HAWK-I, SIRIUS or 2MASS, for a further 100 stars we only have HK s photometry.…”

Section: Photometrymentioning

confidence: 99%

KMOS view of the Galactic centre

Feldmeier-Krause

Neumayer

Schödel

et al. 2015

A&A

106

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Context. The Galactic centre hosts a crowded, dense nuclear star cluster with a half-light radius of 4 pc. Most of the stars in the Galactic centre are cool late-type stars, but there are also > ∼ 100 hot early-type stars in the central parsec of the Milky Way. These stars are only 3−8 Myr old. Aims. Our knowledge of the number and distribution of early-type stars in the Galactic centre is incomplete. Only a few spectroscopic observations have been made beyond a projected distance of 0.5 pc of the Galactic centre. The distribution and kinematics of earlytype stars are essential to understand the formation and growth of the nuclear star cluster. Methods. We cover the central >4 pc 2 (0.75 sq. arcmin) of the Galactic centre using the integral-field spectrograph KMOS (VLT). We extracted more than 1000 spectra from individual stars and identified early-type stars based on their spectra. Results. Our data set contains 114 bright early-type stars: 6 have narrow emission lines, 23 are Wolf-Rayet stars, 9 stars have featureless spectra, and 76 are O/B type stars. Our wide-field spectroscopic data confirm that the distribution of young stars is compact, with 90% of the young stars identified within 0.5 pc of the nucleus. We identify 24 new O/B stars primarily at large radii. We estimate photometric masses of the O/B stars and show that the total mass in the young population is > ∼ 12 000 M . The O/B stars all appear to be bound to the Milky Way nuclear star cluster, while less than 30% belong to the clockwise rotating disk. We add one new star to the sample of stars affiliated with this disk. Conclusions. The central concentration of the early-type stars is a strong argument that they have formed in situ. An alternative scenario, in which the stars formed outside the Galactic centre in a cluster that migrated to the centre, is refuted. A large part of the young O/B stars is not on the disk, which either means that the early-type stars did not all form on the same disk or that the disk is dissolving rapidly.

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Section: Photometrymentioning

confidence: 99%

KMOS view of the Galactic centre

Feldmeier-Krause

Neumayer

Schödel

et al. 2015

A&A

106

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“…Cepheids offer an important advantage in this regard in that distances can be derived from relations that allow the reddening and the distance to be determined together and unambiguously when observations in two colours are available-for example, V and I or J and K Sprovided the reddening law is known. Recent work 19 has indicated that the law of reddening is different towards the Galactic bulge from that adopted elsewhere 24 and here we use: A K =(0.494±0,006)E (J-K) from ref. 19 and A I = (1.125±0.09)E (V-I) , which was found by the same method 25 .…”

Section: Distances and Interstellar Absorptionsmentioning

confidence: 99%

“…Recent work 19 has indicated that the law of reddening is different towards the Galactic bulge from that adopted elsewhere 24 and here we use: A K =(0.494±0,006)E (J-K) from ref. 19 and A I = (1.125±0.09)E (V-I) , which was found by the same method 25 . It should be noted that the relation in V and I may be somewhat more complex than the one given 25 .…”

Section: Distances and Interstellar Absorptionsmentioning

confidence: 99%

Cepheid variables in the flared outer disk of our galaxy

Feast

Menzies

Matsunaga

et al. 2014

Nature

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Flaring and warping of the disk of the Milky Way have been inferred from observations of atomic hydrogen 1,2 but stars associated with flaring have not hitherto been reported. In the area beyond the Galactic centre the stars are largely hidden from view by dust, and the kinematic distances of the gas cannot be estimated. Thirty-two possible Cepheid stars (young pulsating variable stars) in the direction of the Galactic bulge were recently identified 3 . With their wellcalibrated period-luminosity relationships, Cepheid stars are useful distance indicators 4 . When observations of these stars are made in two colours, so that their distance and reddening can be determined simultaneously, the problems of dust obscuration are minimized. Here we report that five of the candidates are classical Cepheid stars. These five stars are distributed from approximately one to two kiloparsecs above and below the plane of the Galaxy, at radial distances of about 13 to 22 kiloparsecs from the centre. The presence of these relatively young (less than 130 million years old) stars so far from the Galactic plane is puzzling, unless they are in the flared outer disk. If so, they may be associated with the outer molecular arm 5 .

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“…Conservatively, errors were tentatively adopted from the isochrones that bracket the best solution. Throughout this paper we use the extinction law of Nishiyama et al (2006Nishiyama et al ( , 2008Nishiyama et al ( , 2009) and R V = 2.6 (Nataf et al 2013). We discarded many candidates during this step, typically because the scatter around the best-fitting isochrones were large, indicating differential reddening; this is expected if instead of a cluster there is a hole in the dust.…”

Section: Vvv Cc168mentioning

confidence: 99%

Candidate star clusters toward the inner Milky Way discovered on deep-stackedK_S-band images from the VVV Survey

Ivanov

Piatti

Beamin

et al. 2017

A&A

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Context. The census of star clusters in the inner Milky Way is incomplete because of extinction and crowding. Aims. We embarked on a program to expand the star cluster list in the direction of the inner Milky Way using deep stacks of K S -band images from the VISTA Variables in Via Lactea (VVV) Survey. Methods. We applied an automated two-step procedure to the point-source catalog derived from the deep K S images: first, we identified overdensities of stars, and then we selected only candidate clusters with probable member stars that match an isochrone with a certain age, distance, and extinction on the color-magnitude diagram.Results. This pilot project only investigates the cluster population in part of one VVV tile, that is, b201. We identified nine cluster candidates and estimated their parameters. The new candidates are compact with a typical radius on the sky of ∼0.2-0.4 arcmin (∼0.4-1.6 pc at their estimated distances). They are located at distances of ∼5-14 kpc from the Sun and are subject to moderate extinction of E(B − V) = 0.4-1.0 mag. They are sparse, probably evolved, with typical ages log(t/1 yr) ∼9. Based on the locations of the objects inside the Milky Way, we conclude that one of these objects is probably associated with the disk or halo and the remaining objects are associated with the bulge or the halo. Conclusions. The cluster candidates reported here push the VVV Survey cluster detection to the limit. These new objects demonstrate that the VVV survey has the potential to identify thousands of additional cluster candidates. The sub-arcsec angular resolution and the near-infrared wavelength regimen give it a critical advantage over other surveys.

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Interstellar Extinction Law in theJ,H, andK_sBands toward the Galactic Center

Cited by 244 publications

References 27 publications

KMOS view of the Galactic centre

KMOS view of the Galactic centre

Cepheid variables in the flared outer disk of our galaxy

Candidate star clusters toward the inner Milky Way discovered on deep-stackedK_S-band images from the VVV Survey

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Interstellar Extinction Law in theJ,H, andKsBands toward the Galactic Center

Cited by 244 publications

References 27 publications

KMOS view of the Galactic centre

KMOS view of the Galactic centre

Cepheid variables in the flared outer disk of our galaxy

Candidate star clusters toward the inner Milky Way discovered on deep-stackedKS-band images from the VVV Survey

Contact Info

Product

Resources

About

Interstellar Extinction Law in theJ,H, andK_sBands toward the Galactic Center

Candidate star clusters toward the inner Milky Way discovered on deep-stackedK_S-band images from the VVV Survey