scholarly journals Searching for emission line and OB stars in Cl 1806-20 using a NIR narrow-band technique

2010 ◽  
Vol 6 (S272) ◽  
pp. 606-607 ◽  
Author(s):  
Michelle L. Edwards ◽  
Reba M. Bandyopadhyay ◽  
Stephen S. Eikenberry ◽  
Valerie J. Mikles ◽  
Dae-Sik Moon
Keyword(s):  
Emission Line ◽  
Massive Star ◽  
Near Infrared ◽  
Narrow Band ◽  
Massive Stars ◽  
Narrow Band Imaging ◽  
Ob Stars ◽  
Luminous Blue Variables ◽  
Upper Limit

AbstractWe survey the environment of Cl 1806-20 using near-infrared narrow-band imaging to search for Brγ features indicative of evolved massive stars. Using this technique, we successfully detect previously identified massive stars in the cluster. We detect no new emission line stars, establishing a firm upper limit on the number of Wolf Rayets and Luminous Blue Variables; however, we do find several candidate OB supergiants, which likely represent the bulk of the heretofore undiscovered massive star population.

Emission-line objects near QSO absorbers. I - Narrow-band imaging and candidate list

1990 ◽  
Vol 351 ◽  
pp. 377 ◽  
Author(s):  
Brian Yanny ◽  
Don G. York ◽  
Ted B. Williams
Keyword(s):  
Emission Line ◽  
Narrow Band ◽  
Narrow Band Imaging ◽  
Candidate List

scholarly journals Working Group on Hot Massive Stars (Groupe De Travail Sur Les Etoiles Massives Chaudes)

2000 ◽  
Vol 24 (1) ◽  
pp. 176-185
Author(s):  
Philippe Eenens ◽  
Joseph Cassinelli ◽  
Peter Conti ◽  
Catharine Garmany ◽  
Karel van der Hucht ◽  
...  
Keyword(s):  
Executive Committee ◽  
Working Group ◽  
Collaborative Research ◽  
Massive Stars ◽  
Starburst Galaxies ◽  
General Assembly ◽  
Hot Stars ◽  
Ob Stars ◽  
Luminous Blue Variables

The Working Group on Hot Massive Stars has been officially recognized by the IAU Executive Committee during the XXIII General Assembly in August 1997. Its origins are the Hot Star Newsletter, launched in 1994, and a long tradition of interaction and collaborative research strengthened by a series of meetings on hot beaches. It gathers over 500 researchers working on OB stars, Luminous Blue Variables, Wolf-Rayet stars, and in general all topics related to the evolution of massive stars and to the physics and consequences of winds from hot stars. The very successful recent symposium on “Wolf-Rayet phenomena in massive stars and starburst galaxies” is an indicator of the increasing interest of the extragalactic community in the study of these extraordinary stars.

scholarly journals Luminous Blue Variables, cool hypergiants and some impostors in the H-R diagram

2003 ◽  
Vol 212 ◽  
pp. 38-46
Author(s):  
Roberta M. Humphreys
Keyword(s):  
Magnetic Fields ◽  
Mass Loss ◽  
Surface Activity ◽  
Massive Star ◽  
Massive Stars ◽  
High Mass ◽  
Luminous Blue Variables ◽  
Star Evolution ◽  
High Mass Loss ◽  
Massive Star Evolution

Current observations of the S Dor/LBVs and candidates and the implications for their important role in massive star evolution are reviewed. Recent observations of the cool hypergiants are altering our ideas about their evolutionary state, their atmospheres and winds, and the possible mechanisms for their asymmetric high mass loss episodes which may involve surface activity and magnetic fields. Recent results for IRC+10420, ρ Cas and VY CMa are highlighted. S Dor/LBVs in eruption, and the cool hypergiants in their high mass loss phases with their optically thick winds are not what their apparent spectra and temperatures imply; they are then ‘impostors’ on the H-R diagram. The importance of the very most massive stars, like η Carinae and the ‘supernovae impostors’ are also discussed.

scholarly journals Properties of Lyα emitters at z≃6

2006 ◽  
Vol 2 (14) ◽  
pp. 253-253
Author(s):  
Crystal L. Martin ◽  
Marcin Sawicki ◽  
Alan Dressler ◽  
Patrick J. McCarthy
Keyword(s):  
Emission Line ◽  
Strong Evidence ◽  
Narrow Band ◽  
Narrow Band Imaging ◽  
Line Profiles ◽  
Galactic Winds ◽  
Line Survey

AbstractWe confirm the redshift of several z≃6 objects discovered by our imacs multislit emission-line survey. Their Lyα luminosities are lower than those of galaxies previously discovered using narrow-band imaging, as expected due to the excellent sky-supression inherent to this technique. Based on the line profiles of these objects, we argue that they are extremely young starbursts and find strong evidence for prominent galactic winds. This population of young galaxies is largely beyond the reach of current large surveys that use continuum selection.

scholarly journals Stellar population of the superbubble N 206 in the LMC

2018 ◽  
Vol 615 ◽  
pp. A40 ◽  
Author(s):  
V. Ramachandran ◽  
W.-R. Hamann ◽  
R. Hainich ◽  
L. M. Oskinova ◽  
T. Shenar ◽  
...  
Keyword(s):  
Star Formation ◽  
Massive Star ◽  
Massive Stars ◽  
Mechanical Energy ◽  
Star Formation History ◽  
Photon Flux ◽  
Stellar Winds ◽  
Spectral Analyses ◽  
Ob Stars ◽  
Hot Gas

Context. Clusters or associations of early-type stars are often associated with a “superbubble” of hot gas. The formation of such superbubbles is caused by the feedback from massive stars. The complex N 206 in the Large Magellanic Cloud (LMC) exhibits a superbubble and a rich massive star population. Aims. Our goal is to perform quantitative spectral analyses of all massive stars associated with the N 206 superbubble in order to determine their stellar and wind parameters. We compare the superbubble energy budget to the stellar energy input and discuss the star formation history of the region. Methods. We observed the massive stars in the N 206 complex using the multi-object spectrograph FLAMES at ESO’s Very Large Telescope (VLT). Available ultra-violet (UV) spectra from archives are also used. The spectral analysis is performed with Potsdam Wolf–Rayet (PoWR) model atmospheres by reproducing the observations with the synthetic spectra. Results. We present the stellar and wind parameters of the OB stars and the two Wolf–Rayet (WR) binaries in the N 206 complex. Twelve percent of the sample show Oe/Be type emission lines, although most of them appear to rotate far below critical. We found eight runaway stars based on their radial velocity. The wind-momentum luminosity relation of our OB sample is consistent with the expectations. The Hertzsprung–Russell diagram (HRD) of the OB stars reveals a large age spread (1–30 Myr), suggesting different episodes of star formation in the complex. The youngest stars are concentrated in the inner part of the complex, while the older OB stars are scattered over outer regions. We derived the present day mass function for the entire N 206 complex as well as for the cluster NGC 2018. The total ionizing photon flux produced by all massive stars in the N 206 complex is Q0 ≈ 5 × 1050 s−1, and the mechanical luminosity of their stellar winds amounts to Lmec = 1.7 × 1038 erg s−1. Three very massive Of stars are found to dominate the feedback among 164 OB stars in the sample. The two WR winds alone release about as much mechanical luminosity as the whole OB star sample. The cumulative mechanical feedback from all massive stellar winds is comparable to the combined mechanical energy of the supernova explosions that likely occurred in the complex. Accounting also for the WR wind and supernovae, the mechanical input over the last five Myr is ≈ 2.3 × 1052 erg. Conclusions. The N206 complex in the LMC has undergone star formation episodes since more than 30 Myr ago. From the spectral analyses of its massive star population, we derive a current star formation rate of 2.2 × 10−3 M⊙ yr−1. From the combined input of mechanical energy from all stellar winds, only a minor fraction is emitted in the form of X-rays. The corresponding input accumulated over a long time also exceeds the current energy content of the complex by more than a factor of five. The morphology of the complex suggests a leakage of hot gas from the superbubble.

scholarly journals Eruptive outflow phases of massive stars

2010 ◽  
Vol 6 (S272) ◽  
pp. 571-580
Author(s):  
Nathan Smith
Keyword(s):  
Massive Star ◽  
Massive Stars ◽  
Luminous Blue Variables ◽  
Eta Carinae ◽  
Physical Mechanisms ◽  
Wide Range ◽  
Transient Sources ◽  
Time Expansion ◽  
Optical Transient ◽  
Peak Luminosity

AbstractI review recent progress on understanding eruptions of unstable massive stars, with particular attention to the diversity of observed behavior in extragalatic optical transient sources that are generally associated with giant eruptions of luminous blue variables (LBVs). These eruptions are thought to represent key mass loss episodes in the lives of massive stars. I discuss the possibility of dormant LBVs and implications for the duration of the greater LBV phase and its role in stellar evolution. These eruptive variables show a wide range of peak luminosity, decay time, expansion speeds, and progenitor luminosity, and in some cases they have been observed to suffer multiple eruptions. This broadens our view of massive star eruptions compared to prototypical sources like Eta Carinae, and provides important clues for the nature of the outbursts. I will also review and discuss some implications about the possible physical mechanisms involved, although the cause of the eruptions is not yet understood.

scholarly journals Massive Stars in the Galactic Center

2007 ◽  
Vol 3 (S250) ◽  
pp. 257-264
Author(s):  
F. Martins ◽  
D. J. Hillier ◽  
R. Genzel ◽  
F. Eisenhauer ◽  
T. Ott ◽  
...  
Keyword(s):  
Massive Star ◽  
Near Infrared ◽  
Galactic Center ◽  
Massive Stars ◽  
Evolutionary Status ◽  
Infrared Spectral Range ◽  
Different Types ◽  
Infrared Spectral ◽  
Observational Techniques ◽  
Massive Clusters

AbstractWe present results of two studies aiming at better understanding the properties of massive stars in the Galactic Center. We focus on the youngest and oldest of the three massive clusters harboring this region, namely the Arches and central cluster. We show that the development of powerful observational techniques in the near infrared spectral range (mainly 3D spectroscopy) allows to uncover the entire massive star population in these clusters. Using CMFGEN models, we derive the classical stellar and wind properties of 46 stars, as well as their surface abundances. The latter allow us to investigate in detail their evolutionary status and to identify evolutionary sequences between different types of stars. We thus constrain stellar evolution in the upper part of the HR diagram.

scholarly journals Massive Stars in M31

2016 ◽  
Vol 12 (S329) ◽  
pp. 419-419
Author(s):  
Jamie R. Lomax ◽  
Matthew Peters ◽  
John Wisniewski ◽  
Julianne Dalcanton ◽  
Benjamin Williams ◽  
...  
Keyword(s):  
Emission Line ◽  
Effective Temperature ◽  
Massive Star ◽  
Milky Way ◽  
Massive Stars ◽  
Stellar Populations ◽  
Preliminary Results ◽  
Large Numbers ◽  
Massive Clusters

AbstractMassive stars are intrinsically rare and therefore present a challenge to understand from a statistical perspective, especially within the Milky Way. We recently conducted follow-up observations to the Panchromatic Hubble Andromeda Treasury (PHAT) survey that were designed to detect more than 10,000 emission line stars, including WRs, by targeting regions in M31 previously known to host large numbers of young, massive clusters and very young stellar populations. Because of the existing PHAT data, we are able to derive an effective temperature, bolarimetric luminosity, and extinction for each of our detected stars. We report on preliminary results of the massive star population of our dataset and discuss how our results compare to previous studies of massive stars in M31.

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