Catherine A. Garland

Gas Flows around Two Young Stellar Clusters in NGC 2264

Observations of the dust and gas toward two young stellar clusters, IRS 1 and IRS 2, in the NGC 2264 star-forming region are presented. Continuum emission is used to locate the dusty envelopes around the clusters and individual protostars within, and line emission from the J = 3-2 transitions of HCO+ and H13CO+ is used to diagnose the gas flows around them. The molecular abundance, velocity centroid, and dispersion are approximately constant across the IRS 1 clump. With these constraints, the self-absorbed HCO+ lines are modeled as a large-scale collapse, with speed vin = 0.3 km s -1 and mass infall rate = 4 × 10-4 M☉ yr-1 falling onto an expanding central core. The signature of large-scale collapse, with a similar speed and mass infall rate, is also found toward IRS 2 but again appears disrupted at small scales. Individual protostars are resolved in this cluster and their size and velocity dispersion show that the stellar system is currently bound and no older than 5 × 105 yr, but is destined to become unbound and disperse as the surrounding cloud material is lost.

Three-dimensional spectroscopy of local luminous compact blue galaxies: kinematic maps of a sample of 22 objects

We use three-dimensional optical spectroscopy observations of a sample of 22 local luminous compact blue galaxies (LCBGs) to create kinematic maps. By means of these, we classify the kinematics of these galaxies into three different classes: rotating disc (RD), perturbed rotation (PR) and complex kinematics (CK). We find 48 per cent are RDs, 28 per cent are PRs and 24 per cent are CKs. RDs show rotational velocities that range between similar to 50 and similar to 200 km s(-1), and dynamical masses that range between similar to 1 x 10(9) and similar to 3 x 10(10) M(circle dot). We also address the following two fundamental questions through the study of the kinematic maps: (i) What processes are triggering the current starburst in LCBGs? We search our maps of the galaxy velocity fields for signatures of recent interactions and close companions that may be responsible for the enhanced star formation in our sample. We find that 5 per cent of objects show evidence of a recent major merger, 10 per cent of a minor merger and 45 per cent of a companion. This argues in favour of ongoing interactions with close companions as a mechanism for the enhanced star formation activity in these galaxies. (ii) What processes may eventually quench the current starbust in LCBGs? Velocity and velocity width maps, together with emission line ratio maps, can reveal signatures of active galactic nuclei (AGNs) activity or supernova (SN)-driven galactic winds that could halt the current burst. We find only 5 per cent of objects with clear evidence of AGN activity and 27 per cent with kinematics consistent with SN-driven galactic winds. Therefore, a different mechanism may be responsible for quenching the star formation in LCBGs. Finally, from our analysis, we find that the velocity widths of RDs, rather than accounting exclusively for the rotational nature of these objects, may account as well for other kinematic components and may not be good tracers of their dynamical masses.

Three-dimensional spectroscopy of local luminous compact blue galaxies: kinematic maps of a sample of 22 objects: 3D spectroscopy of local Luminous Compact Blue Galaxies

We use three-dimensional optical spectroscopy observations of a sample of 22 local luminous compact blue galaxies (LCBGs) to create kinematic maps. By means of these, we classify the kinematics of these galaxies into three different classes: rotating disc (RD), perturbed rotation (PR) and complex kinematics (CK). We find 48 per cent are RDs, 28 per cent are PRs and 24 per cent are CKs. RDs show rotational velocities that range between similar to 50 and similar to 200 km s(-1), and dynamical masses that range between similar to 1 x 10(9) and similar to 3 x 10(10) M(circle dot). We also address the following two fundamental questions through the study of the kinematic maps: (i) What processes are triggering the current starburst in LCBGs? We search our maps of the galaxy velocity fields for signatures of recent interactions and close companions that may be responsible for the enhanced star formation in our sample. We find that 5 per cent of objects show evidence of a recent major merger, 10 per cent of a minor merger and 45 per cent of a companion. This argues in favour of ongoing interactions with close companions as a mechanism for the enhanced star formation activity in these galaxies. (ii) What processes may eventually quench the current starbust in LCBGs? Velocity and velocity width maps, together with emission line ratio maps, can reveal signatures of active galactic nuclei (AGNs) activity or supernova (SN)-driven galactic winds that could halt the current burst. We find only 5 per cent of objects with clear evidence of AGN activity and 27 per cent with kinematics consistent with SN-driven galactic winds. Therefore, a different mechanism may be responsible for quenching the star formation in LCBGs. Finally, from our analysis, we find that the velocity widths of RDs, rather than accounting exclusively for the rotational nature of these objects, may account as well for other kinematic components and may not be good tracers of their dynamical masses.

3D Spectroscopy of Local Luminous Compact Blue Galaxies: Kinematic Maps of a Sample of 22 Objects

We use three-dimensional optical spectroscopy observations of a sample of 22 local luminous compact blue galaxies (LCBGs) to create kinematic maps. By means of these, we classify the kinematics of these galaxies into three different classes: rotating disc (RD), perturbed rotation (PR) and complex kinematics (CK). We find 48 per cent are RDs, 28 per cent are PRs and 24 per cent are CKs. RDs show rotational velocities that range between similar to 50 and similar to 200 km s(-1), and dynamical masses that range between similar to 1 x 10(9) and similar to 3 x 10(10) M(circle dot). We also address the following two fundamental questions through the study of the kinematic maps: (i) What processes are triggering the current starburst in LCBGs? We search our maps of the galaxy velocity fields for signatures of recent interactions and close companions that may be responsible for the enhanced star formation in our sample. We find that 5 per cent of objects show evidence of a recent major merger, 10 per cent of a minor merger and 45 per cent of a companion. This argues in favour of ongoing interactions with close companions as a mechanism for the enhanced star formation activity in these galaxies. (ii) What processes may eventually quench the current starbust in LCBGs? Velocity and velocity width maps, together with emission line ratio maps, can reveal signatures of active galactic nuclei (AGNs) activity or supernova (SN)-driven galactic winds that could halt the current burst. We find only 5 per cent of objects with clear evidence of AGN activity and 27 per cent with kinematics consistent with SN-driven galactic winds. Therefore, a different mechanism may be responsible for quenching the star formation in LCBGs. Finally, from our analysis, we find that the velocity widths of RDs, rather than accounting exclusively for the rotational nature of these objects, may account as well for other kinematic components and may not be good tracers of their dynamical masses.

The Neutral ISM in Nearby Luminous Compact Blue Galaxies

Luminous Compact Blue Galaxies (LCBGs) are ∼L*, blue, high surface brightness, high metallicity, vigorously starbursting galaxies with an underlying older stellar population [1, 2]. They include a variety of morphological types, such as spiral, polar-ring, interacting/merging and peculiar galaxies. They have optical diameters of a few kpc, but are more luminous and more metal rich than the Blue Compact Dwarf Galaxies widely studied in the nearby Universe, e.g. [3, 4].