The Nature of the GC HEI Emission Line Stars

Najarro, F.; Hillier, D. J.; Kudritzki, R. P.; Krabbe, A.; Genzel, R.; Lutz, D.; Drapatz, S.; Geballe, T. R.

doi:10.1007/978-94-011-0752-5_39

Cited by 110 publications

(216 citation statements)

References 13 publications

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“…We fixed K as estimated by T p 24,400 eff1 Najarro et al (1997) and used the square-root limb-darkening law, taking the values of the limb-darkening coefficients from Claret (2000) for a LTE ATLAS9 (Kurucz 1993) stellar atmosphere model with K, (cgs), a tur-T p 24,000 log g p 3.0 eff bulent velocity of 2 km s Ϫ1 , and solar metallicity. We fixed gravity-brightening exponents and albedos to unity from theoretical values for stars at such temperatures.…”

Section: Light-curve Analysismentioning

confidence: 99%

“…Using a radius of (the mean radius given by WD for an orbital R p 59.7 R , separation of 140.6 R , ) and an effective temperature of K (Najarro et al 1997), we can estimate the T p 24400 . It is highly unlikely that each component of IRS 16SW…”

Section: Light-curve Analysismentioning

confidence: 99%

“…Assuming the orbital separation as calculated by Martins et al (2006) is correct (if it is smaller, then will be even L/L Edd larger), this calculation implies that the temperature of Najarro et al (1997) is an overestimate. A change in the assumed affects the WD model parameters; specifically, a decrease T eff in by a few thousand kelvins will decrease the inclination T eff angle i, and thus increase the masses of the stars, by more than the formal 1 j uncertainties given by WD.…”

mentioning

confidence: 96%

“…It is readily apparent from the depths of the eclipses that the two stars have near-equal fluxes, and from the depth ratio that they have near-equal surface brightnesses, yet Martins et al (2006) see only one set of spectroscopic lines. However, since the spectral features used by Martins et al (2006) are wind lines, with strong characteristic P Cygni profiles (Najarro et al 1997), differences in wind strength or small differences in the effective temperatures of the stars could easily conspire to make detection of the second set of lines difficult.…”

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confidence: 99%

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The Nature of the Variable Galactic Center Source GCIRS 16SW Revisited: A Massive Eclipsing Binary

Peeples

Bonanos

DePoy

et al. 2006

ApJ

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We present a reanalysis of our H-and K-band photometry and light curves for GCIRS 16SW, a regular periodic source near the Galactic center. These data include those presented by DePoy et al.; we correct a sign error in their reduction, finding GCIRS 16SW to be an eclipsing binary with no color variations. We find the system to be an equal-mass overcontact binary (both stars overfilling their Roche lobes) in a circular orbit with a period days and an inclination angle . This confirms and strengthens the findings of Martins et P p 19.4513 i p 71Њ al. that GCIRS 16SW is an eclipsing binary composed of two ∼50 M , stars, further supporting evidence of recent star formation very close to the Galactic center. Finally, the calculated luminosity of each component is close to the Eddington luminosity, implying that the temperature of 24,400 K given by Najarro et al. might be overestimated for these evolved stars.

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Section: Light-curve Analysismentioning

confidence: 99%

Section: Light-curve Analysismentioning

confidence: 99%

mentioning

confidence: 96%

mentioning

confidence: 99%

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The Nature of the Variable Galactic Center Source GCIRS 16SW Revisited: A Massive Eclipsing Binary

Peeples

Bonanos

DePoy

et al. 2006

ApJ

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“…Over 120 members of the YNC have been identified via spectroscopy showing either hydrogen and helium lines or featureless blue continuum characteristic of hot Wolf-Rayet (WR) or OB stars (Allen et al 1990;Krabbe et al 1991Krabbe et al , 1995Blum et al 1995;Tamblyn et al 1996;Najarro et al 1997;Ghez et al 2003;Paumard et al 2006;Bartko et al 2010;Do et al 2013). The current generation of surveys utilize adaptive optics fed integral field spectroscopic instruments such as OSIRIS on Keck or SINFONI on VLT.…”

Section: The Young Nuclear Clustermentioning

confidence: 99%

Young stars in the Galactic center

Lu¹,

Ghez

Morris

et al. 2013

Proc. IAU

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Abstract. The central parsec of our Galaxy hosts not only a supermassive black hole, but also a large population of young stars (age <6 Myr) whose presence is puzzling given how inhospitable the region is for star formation. The strong tidal forces require gas densities many orders of magnitude higher than is found in typical molecular clouds. Kinematic observations of this young nuclear cluster show complex structures, including a well-defined inner disk, but also a substantial off-disk population. Spectroscopic and photometric measurements indicate the initial mass function (IMF) differs significantly from the canonical IMF found in the solar neighborhood. These observations have led to a number of proposed star formation scenarios, such as an infalling massive star cluster, a single infalling molecular cloud, or cloud-cloud collisions. I will review recent works on the young stars in the central parsec and discuss connections with young nuclear star clusters in other galaxies, such as M31, and with star formation in the larger central molecular zone.

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Really Cool Stars and the Star Formation History at the Galactic Center

Blum

Ramrez

Sellgren

et al. 2003

Proceedings of the Galactic Center Workshop 2002

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We present λ/∆λ = 550 to 1200 near infrared H and K spectra for a magnitude limited sample of 79 asymptotic giant branch and cool supergiant stars in the central ≈ 5 pc (diameter) of the Galaxy. We use a set of similar spectra obtained for solar neighborhood stars with known T eff and M bol that is in the same range as the Galactic center (GC) sample to derive T eff and M bol for the GC sample. We then construct the Hertzsprung-Russell (HRD) diagram for the GC sample. Using an automated maximum likelihood routine, we derive a coarse star formation history of the GC. We find (1) roughly 75% of the stars formed in the central few pc are older than 5 Gyr; (2) the star formation rate (SFR) is variable over time, with a roughly 4 times higher star formation rate in the last 1 Visiting Astronomer, Cerro Tololo Interamerican Observatory, National Optical Astronomy Observatories, which is operated by Associated Universities for Research in Astronomy, Inc., under cooperative agreement with the National Science Foundation -2 -100 Myr compared to the average SFR; (3) our model can only match dynamical limits on the total mass of stars formed by limiting the IMF to masses above 0.7 M ⊙ . This could be a signature of mass segregation or of the bias toward massive star formation from the unique star formation conditions in the GC; (4) blue supergiants account for 12 % of the total sample observed, and the ratio of red to blue supergiants is roughly 1.5; (5)

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The Nature of the GC HEI Emission Line Stars

Cited by 110 publications

References 13 publications

The Nature of the Variable Galactic Center Source GCIRS 16SW Revisited: A Massive Eclipsing Binary

The Nature of the Variable Galactic Center Source GCIRS 16SW Revisited: A Massive Eclipsing Binary

Young stars in the Galactic center

Really Cool Stars and the Star Formation History at the Galactic Center

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