Angular momentum and the formation of stars and black holes

Larson, Richard B.

doi:10.1088/0034-4885/73/1/014901

Cited by 30 publications

(26 citation statements)

References 193 publications

(304 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The origin of this peak may be related to the formation or early evolution of these stars. Massive stars inherit their angular momentum from their parental cloud that contains more than enough angular momentum to spin up the protostar to critical rotation (see Larson 2010). Interestingly, Lin et al (2011) find that gravitational torques prohibit a star from rotating above ∼50% of its break-up speed during formation.…”

Section: The Low-velocity Peakmentioning

confidence: 99%

The VLT-FLAMES Tarantula Survey

Ramírez-Agudelo

Simón‐Díaz

Sana

et al. 2013

A&A

244

281

View full text Add to dashboard Cite

Context. The 30 Doradus (30 Dor) region of the Large Magellanic Cloud, also known as the Tarantula nebula, is the nearest starburst region. It contains the richest population of massive stars in the Local Group, and it is thus the best possible laboratory to investigate open questions on the formation and evolution of massive stars. Aims. Using ground-based multi-object optical spectroscopy obtained in the framework of the VLT-FLAMES Tarantula Survey (VFTS), we aim to establish the (projected) rotational velocity distribution for a sample of 216 presumably single O-type stars in 30 Dor. The sample is large enough to obtain statistically significant information and to search for variations among subpopulations -in terms of spectral type, luminosity class, and spatial location -in the field of view. Methods. We measured projected rotational velocities, e sin i, by means of a Fourier transform method and a profile fitting method applied to a set of isolated spectral lines. We also used an iterative deconvolution procedure to infer the probability density, P( e ), of the equatorial rotational velocity, e . Results. The distribution of e sin i shows a two-component structure: a peak around 80 km s −1 and a high-velocity tail extending up to ∼600 km s −1 . This structure is also present in the inferred distribution P( e ) with around 80% of the sample having 0 < e ≤ 300 km s −1 and the other 20% distributed in the high-velocity region. The presence of the low-velocity peak is consistent with what has been found in other studies for late O-and early B-type stars. Conclusions. Most of the stars in our sample rotate with a rate less than 20% of their break-up velocity. For the bulk of the sample, mass loss in a stellar wind and/or envelope expansion is not efficient enough to significantly spin down these stars within the first few Myr of evolution. If massive-star formation results in stars rotating at birth with a large portion of their break-up velocities, an alternative braking mechanism, possibly magnetic fields, is thus required to explain the present-day rotational properties of the O-type stars in 30 Dor. The presence of a sizeable population of fast rotators is compatible with recent population synthesis computations that investigate the influence of binary evolution on the rotation rate of massive stars. Even though we have excluded stars that show significant radial velocity variations, our sample may have remained contaminated by post-interaction binary products. That the highvelocity tail may be populated primarily (and perhaps exclusively) by post-binary interaction products has important implications for the evolutionary origin of systems that produce gamma-ray bursts.

show abstract

Section: The Low-velocity Peakmentioning

confidence: 99%

The VLT-FLAMES Tarantula Survey

Ramírez-Agudelo

Simón‐Díaz

Sana

et al. 2013

A&A

244

281

View full text Add to dashboard Cite

show abstract

“…However, it is not known how the cold gas is deposited into the inner nucleus of the galaxy. This angular momentum problem is similar for the growth of SMBHs and the formation of stars (Larson 2010) and is even more severe for SMBHs because they are smaller than stars in relation to the size of the system in which they form. Thus, the mass that SMBHs may achieve is likely to be strongly regulated by the efficiency of angular momentum transfer during the fuel process.…”

Section: Introductionmentioning

confidence: 99%

A precessing molecular jet signaling an obscured, growing supermassive black hole in NGC 1377?

Aalto

Costagliola

Müller

et al. 2016

A&A

View full text Add to dashboard Cite

With high resolution (0. 25 × 0. 18) ALMA CO 3−2 (345 GHz) observations of the nearby (D = 21 Mpc, 1 = 102 pc), extremely radio-quiet galaxy NGC 1377, we have discovered a high-velocity, very collimated nuclear outflow which we interpret as a molecular jet with a projected length of ±150 pc. The launch region is unresolved and lies inside a radius r < 10 pc. Along the jet axis we find strong velocity reversals where the projected velocity swings from −150 km s −1 to +150 km s −1 . A simple model of a molecular jet precessing around an axis close to the plane of the sky can reproduce the observations. The velocity of the outflowing gas is difficult to constrain due to the velocity reversals but we estimate it to be between 240 and 850 km s −1 and the jet to precess with a period P = 0.3−1.1 Myr. The CO emission is clumpy along the jet and the total molecular mass in the high-velocity (±(60 to 150 km s −1 )) gas lies between 2 × 10 6 M (light jet) and 2 × 10 7 M (massive jet). There is also CO emission extending along the minor axis of NGC 1377. It holds >40% of the flux in NGC 1377 and may be a slower, wide-angle molecular outflow which is partially entrained by the molecular jet. We discuss the driving mechanism of the molecular jet and suggest that it is either powered by a (faint) radio jet or by an accretion disk-wind similar to those found towards protostars. It seems unlikely that a massive jet could have been driven out by the current level of nuclear activity which should then have undergone rapid quenching. The light jet would only have expelled 10% of the inner gas and may facilitate nuclear activity instead of suppressing it. The nucleus of NGC 1377 harbours intense embedded activity and we detect emission from vibrationally excited HCN J = 4−3 ν 2 = 1 f which is consistent with hot gas and dust. We find large columns of H 2 in the centre of NGC 1377 which may be a sign of a high rate of recent gas infall. The dynamical age of the molecular jet is short (<1 Myr), which could imply that it is young and consistent with the notion that NGC 1377 is caught in a transient phase of its evolution. However, further studies are required to determine the age of the molecular jet, its mass and the role it is playing in the growth of the nucleus of NGC 1377.

show abstract

“…These cloud cores are slowly rotating but have very large radii, and thus have high initial angular momenta. This has led to the "angular momentum problem" in which the initial angular momentum of a cloud core is at least three orders of magnitude greater than the resulting star (Goodman et al 1993;Bodenheimer 1995;Larson 2010) and must be redistributed or removed during collapse.…”

Section: Introductionmentioning

confidence: 99%

What Sets the Initial Rotation Rates of Massive Stars?

Rosen

Krumholz

Ramírez-Ruiz

2012

ApJ

View full text Add to dashboard Cite

The physical mechanisms that set the initial rotation rates in massive stars are a crucial unknown in current star formation theory. Observations of young, massive stars provide evidence that they form in a similar fashion to their low-mass counterparts. The magnetic coupling between a star and its accretion disk may be sufficient to spin down low-mass pre-main sequence (PMS) stars to well below breakup at the end stage of their formation when the accretion rate is low. However, we show that these magnetic torques are insufficient to spin down massive PMS stars due to their short formation times and high accretion rates. We develop a model for the angular momentum evolution of stars over a wide range in mass, considering both magnetic and gravitational torques. We find that magnetic torques are unable to spin down either low or high mass stars during the main accretion phase, and that massive stars cannot be spun down significantly by magnetic torques during the end stage of their formation either. Spin-down occurs only if massive stars' disk lifetimes are substantially longer or their magnetic fields are much stronger than current observations suggest.

show abstract

Angular momentum and the formation of stars and black holes

Cited by 30 publications

References 193 publications

The VLT-FLAMES Tarantula Survey

The VLT-FLAMES Tarantula Survey

A precessing molecular jet signaling an obscured, growing supermassive black hole in NGC 1377?

What Sets the Initial Rotation Rates of Massive Stars?

Contact Info

Product

Resources

About